ArticlePDF Available

Abstract and Figures

Out of the 1114 strains belonging to 29 genera and 105 species of microbes (molds, yeasts and bacteria) isolated from different sources [clinical cases, environment (water, air, soil, droppings of lizards and birds), food and healthy animals], 38.2% were sensitive to lemongrass oil discs containing 50 μg oil/disc. All molds, yeasts, Lactobacillus acidophilus, Morganella morganii, most of the Bacillus spp. strains (84.3%), aeromonads (78%), Edwardsiella spp. (73.9%), 53.6% pseudomonads, 53.1% streptococci and 50% of Budvicia aquatica and Leminorella ghirmontii strains were sensitive to lemongrass oil (LGO). On the other hand, all Hafnea alvei, Laclercia adecarboxylata, Xenorhabdus luminescens and majority of Salmonella enterica (98.3%), Citrobacter spp. (93.7%), Providencia spp. and Kluyvera cryocrescens (83.3%), Enterobacter spp. (78.2%), Proteus spp. (78%), Escherichia spp. (77.7%), enterococci (73.7%), Serratia spp. (75%) and Erwinia ananas (75%), Pragia fontium (70.6%), staphylococci (69.8%) and Klebsiella spp. (62.7%) strains were resistant to LGO. MIC of LGO for sensitive strains (tested against discs containing 50 μg LGO) varied from 1 μg to 32 μg /ml while none of the resistant strains had MIC <64 μg LGO/ ml. MIC for yeast strains was the least i.e., 1 μg LGO/ ml. LGO had microbicidal activity on E. coli, S. aureus and Candida albicans. LGO instantly killed C. albicans and E. coli, and S. aureus in 10 min at 1 mg/ ml concentration, indicating of its wide spectrum antimicrobial activity at easily achievable concentrations. Study also indicated that LGO is more effective on enterococci in aerobic instead of microaerophilic growth conditions, it is indicative that in-vivo sensitivity results may differ from in-vitro tests.
Content may be subject to copyright.
International Research of Pharmacy and Pharmacology (ISSN 2251-0176) Vol. 1(9) pp. 228-236, December 2011
Available online http://www.interesjournals.org/IRJPP
Copyright © 2011 International Research Journals
Full Length Research Paper
Antimicrobial activity of lemongrass (Cymbopogon
citratus) oil against microbes of environmental,
clinical and food origin
Bhoj Raj Singh1*, Vidya Singh2, Raj Karan Singh2 and N. Ebibeni1
1ICAR Research Complex for NEH Region, Jharnapani, Nagaland, India
2NRC on Mithun, Jharnapani, Nagaland, India
Accepted 30 November, 2011
Out of the 1114 strains belonging to 29 genera and 105 species of microbes (molds, yeasts and
bacteria) isolated from different sources [clinical cases, environment (water, air, soil, droppings
of lizards and birds), food and healthy animals], 38.2% were sensitive to lemongrass oil discs
containing 50 µg oil/disc. All molds, yeasts, Lactobacillus acidophilus, Morganella morganii,
most of the Bacillus spp. strains (84.3%), aeromonads (78%), Edwardsiella spp. (73.9%), 53.6%
pseudomonads, 53.1% streptococci and 50% of Budvicia aquatica and Leminorella ghirmontii
strains were sensitive to lemongrass oil (LGO). On the other hand, all Hafnea alvei, Laclercia
adecarboxylata, Xenorhabdus luminescens and majority of Salmonella enterica (98.3%),
Citrobacter spp. (93.7%), Providencia spp. and Kluyvera cryocrescens (83.3%), Enterobacter
spp. (78.2%), Proteus spp. (78%), Escherichia spp. (77.7%), enterococci (73.7%), Serratia spp.
(75%) and Erwinia ananas (75%), Pragia fontium (70.6%), staphylococci (69.8%) and Klebsiella
spp. (62.7%) strains were resistant to LGO. MIC of LGO for sensitive strains (tested against discs
containing 50 µg LGO) varied from 1 µg to 32 µg /ml while none of the resistant strains had MIC
<64 µg LGO/ ml. MIC for yeast strains was the least i.e., 1 µg LGO/ ml. LGO had microbicidal
activity on E. coli, S. aureus and Candida albicans. LGO instantly killed C. albicans and E. coli,
and S. aureus in 10 min at 1 mg/ ml concentration, indicating of its wide spectrum antimicrobial
activity at easily achievable concentrations. Study also indicated that LGO is more effective on
enterococci in aerobic instead of microaerophilic growth conditions, it is indicative that in-vivo
sensitivity results may differ from in-vitro tests.
Keywords: Lemongrass oil, Antimicrobial activity, Microbes
INTRODUCTION
Of more than 400,000 spp. of tropical flowering plants,
varieties of several thousands species have been used
for their medicinal properties in traditional medicine (Ali-
Shtayeh and Abu Ghdeib, 1999; Odugbemi, 2006).
Lemongrass (Cymbopogon citratus), a tall perennial
grass comprising of about 55 species, is native to warm
region and grows in almost all tropical and subtropical
countries (Cheel et al., 2005). The biologically active
constituent of lemon grass is citral constituting more
than 75% (w/w) of its essential oil (Huynh et al., 2008).
Lemongrass is widely used as an essential ingredient in
Asian cuisines because of its sharp lemon flavour.
Herbal tea of lemongrass is used as sedatives,
febrifuge and immunostimulant in India (Pearson, 2010;
Brian and Ikhlas, 2002) while, lemongrass essential oil
*Corresponding authoremail: brs1762@gmail.com
is applied for its medicinal value to cure acne, oily skin,
scabies, flatulence, headaches, blood circulation
problems (Pearson, 2010) and excessive perspiration
due to its antimicrobial and antibacterial activities
(Lawless, 1995). It has also been used as carminative,
stimulant, emmenagogue, diuretic and antiseptic (Ghani
et al., 1997). In Nigeria, lemon grass is used for
stomach problem and it is also used in combination with
few other plants for effective treatment of malaria
(Aibinu et al., 2007) and typhoid (Depken, 2011).
Although, in a few preliminary antimicrobial
screenings, LGO had shown no activity against four
Gram positive (Bacillus subtilis, Corynebacterium
diphtheriae, Streptococcus pyogenes and
Staphylococcus aureus) and three Gram negative
(Salmonella paratyphi A, Escherichia coli and
Pseudomonas aeruginosa) bacterial cultures (Saify et
al., 2000), later on several studies have shown that the
Singh et al. 229
Table 1. Antimicrobial effect of lemongrass oil on strains of different genera of microbes
Microbial strains tested
(Number of species)
Strains
tested
Strain
resistant
Strains
sensitive
% sensitive
strains
% resistant
strains
Aspergillus spp. (2) 11 0 11 100.0 0.0
Candida spp. 7 0 7 100.0 0.0
Lactobacillus acidophilus 1 0 1 100.0 0.0
Morganella morganii 3 0 3 100.0 0.0
Penicillium spp. (1) 3 0 3 100.0 0.0
Bacillus spp. (15) 115 18 97 84.3 15.7
Aeromonas spp. (8) 91 20 71 78.0 22.0
Edwardsiella spp. (2) 23 6 17 73.9 26.1
Micrococcus agilis 3 1 2 66.7 33.3
Pseudomonas spp. (3) 28 13 15 53.6 46.4
Streptococcus spp. (8) 32 15 17 53.1 46.9
Budvicia aquatica 8 4 4 50.0 50.0
Leminorella ghirmontii 2 1 1 50.0 50.0
Klebsiella spp. (3) 110 69 41 37.3 62.7
Staphylococcus spp. (5) 43 30 13 30.2 69.8
Pragia fontium 17 12 5 29.4 70.6
Ervinia ananas 12 9 3 25.0 75.0
Serratia spp. (5) 12 9 3 25.0 75.0
Enterococcus spp. (15) 213 157 56 26.3 73.7
Escherichia spp. (4) 112 87 25 22.3 77.7
Proteus spp. (4) 41 32 9 22.0 78.0
Enterobacter spp. (9) 55 43 12 21.8 78.2
Kluyvera cryocrescens 6 5 1 16.7 83.3
Providencia spp. (2) 6 5 1 16.7 83.3
Citrobacter spp. (3) 95 89 6 6.3 93.7
Salmonella enterica spp. (3) 59 58 1 1.7 98.3
Hafnea alvei 4 4 0 0.0 100.0
Leclercia adecarboxylata 1 1 0 0.0 100.0
Xenorhabdus luminescens 1 1 0 0.0 100.0
lemon grass has antibacterial and antifungal properties
(Ushimaru et al., 2007).
LGO’s antimicrobial properties make it an effective
drug for bacterial and fungal infections. It can be used
in cleaning wounds and treatment of skin diseases such
as ringworm. It can also be used in food poisoning,
staphylococcal infections, and other common infections
of the colon, stomach, and urinary tract. Besides,
bacteria, molds and yeasts, LGO has been reported to
effectively control growth of agent of American
foulbrood disease (AFD), the Paenibacillus larvae
(Alippi et al., 1996) and malaria, the Plasmodium spp
(Pearson, 2010). Although many studies have proved
antimicrobial effect of LGO using reference strains of
variety of bacteria (Chao and Young, 2000; Onawunmi,
1989; Syed et al., 1995; Alam et al., 1994; Sharma et
al., 2003; Saikia et al., 1999) and fungi (Pratt and
Hudson, 1991; Nieto et al., 1993; Abu-Seif, et al.,
2009), only little is known about its action on field
strains of clinical, environmental and food origin.
Therefore, the present study was undertaken to
elucidate the antimicrobial spectrum of LGO through
testing it against 21 isolates of three genera of fungi
and 1085 isolates of common bacteria belonging to 26
genera.
MATERIALS AND METHODS
Lemongrass oil (LGO)
Light yellow colored pure lemongrass oil was obtained
as free gift from Naga Fragrance Pvt. Ltd. Dimapur,
Nagaland, India.
Fungal and bacterial strains
Five Aspergillus niger, six A. flavus, three Penicillium
spp., seven Candida albicans strains and 1093 bacterial
strains of 26 genera (Tables 1, 2, 3) isolated (from
clinical cases, water, fish, ponds, air, soil, cattle, pig,
lizards, birds) and maintained at Microbiology
Laboratory, ICAR Research Complex for NEH Region,
Nagaland Centre, Jharnapani, Nagaland, India, were
revived and checked for purity. Bacterial, yeast and
230 Int. Res. J. Pharm. Pharmacol
Table 2. Antimicrobial effect of lemongrass oil on strains of Gram negative bacteria
Microbial strains tested (Number of
species)
Strains
tested
Strain
resistant
Strains
sensitive
% sensitive
strains
% resistant
strains
Aeromonas caviae 12 2 10 83.3 16.7
A. eucranophila 18 10 8 44.4 55.6
A. hydrophila 18 3 15 83.3 16.7
A. media 9 0 9 100.0 0.0
A. salmonicida ssp. achromogenes 3 2 1 33.3 66.7
A. salmonicida ssp. salmonicida 5 2 3 60.0 40.0
A. salmonicida ssp. smithia 1 0 1 100.0 0.0
A. schubertii 8 0 8 100.0 0.0
A. sobria 3 0 3 100.0 0.0
A. veronii 14 1 13 92.9 7.1
Budvicia aquatica 8 4 4 50.0 50.0
Citrobacter amalonaticus 11 11 0 0.0 100.0
C. diversus 6 6 0 0.0 100.0
C. freundii 78 72 6 7.7 92.3
Edwardsiella hoshiniae 1 1 0 0.0 100.0
Edwardsiella. tarda 22 5 17 77.3 22.7
Enterobacter agglomerans 23 14 9 39.1 60.9
Enterobacter. amnigenus I 9 9 0 0.0 100.0
Enterobacter amnigenus II 3 1 2 66.7 33.3
Enterobacter cancerogenus 1 1 0 0.0 100.0
Enterobacter cloacae 5 5 0 0.0 100.0
Enterobacter gregoviae 11 11 0 0.0 100.0
Enterobacter hormaechei 1 1 0 0.0 100.0
Enterobacter sakazaki 1 1 0 0.0 100.0
Enterobacter spp. 1 0 1 100.0 0.0
Erwinia ananas 12 9 3 25.0 75.0
Escherichia blattae 6 4 2 33.3 66.7
Escherichia coli 96 77 19 19.8 80.2
Escherichia furgusonii 8 4 4 50.0 50.0
Escherichia vulneris 2 2 0 0.0 100.0
Hafnea alvei 4 4 0 0.0 100.0
Klebsiella oxytoca 9 7 2 22.2 77.8
K. pnumoniae ssp. pneumoniae 95 57 38 40.0 60.0
Klebsiella terrigena 6 5 1 16.7 83.3
Kluyvera cryocrescens 6 5 1 16.7 83.3
Leclercia adecarboxylata 1 1 0 0.0 100.0
Leminorella ghirmontii 2 1 1 50.0 50.0
Morganella morganii 3 0 3 100.0 0.0
Proteus mirabilis 12 8 4 33.3 66.7
Proteus myxofaciens 1 0 1 100.0 0.0
Proteus penneri 19 17 2 10.5 89.5
Proteus vulgaris 9 7 2 22.2 77.8
Pragia fontium 17 12 5 29.4 70.6
Providencia heimbachae 1 0 1 100.0 0.0
Providencia rettgeri 5 5 0 0.0 100.0
Pseudomonas aeruginosa 2 2 0 0.0 100.0
Pseudomonas fluorescens 1 1 0 0.0 100.0
Pseudomonas spp 25 10 15 60.0 40.0
Salmonella enterica ssp. houtenae 3 3 0 0.0 100.0
Salmonella enterica ssp. indica 45 44 1 2.2 97.8
Salmonella enterica ssp. salamae 11 11 0 0.0 100.0
Serratia fonticola 1 1 0 0.0 100.0
Serratia marcescens 2 2 0 0.0 100.0
Serratia odorifera 5 5 0 0.0 100.0
Serratia plymuthica 1 1 0 0.0 100.0
Serratia rubidiae 3 0 3 100.0 0.0
Xenorhabdus luminescens 1 1 0 0.0 100.0
Singh et al. 231
Table 3. Antimicrobial effect of lemongrass oil on strains of Gram positive bacteria and fungi
Microbial strains tested
(Number of species)
Strains
tested
Strain
resistant
Strains
sensitive
% sensitive
strains
% resistant
strains
Aspergillus flavus 6 0 6 100.0 0.0
Aspergillus niger 5 0 5 100.0 0.0
Bacillus anthracoides 3 0 3 100.0 0.0
Bacillus badius 7 0 7 100.0 0.0
Bacillus brevis 4 1 3 75.0 25.0
Bacillus circulans 4 0 4 100.0 0.0
Bacillus coaggulans 51 10 41 80.4 19.6
Bacillus laterosporus 1 0 1 100.0 0.0
Bacillus lentus 8 0 8 100.0 0.0
Bacillus licheniformis 6 6 0 0.0 100.0
Bacillus marcerans 4 0 4 100.0 0.0
Bacillus mycoides 2 0 2 100.0 0.0
Bacillus pentothenticus 16 1 15 93.8 6.3
Bacillus stearothermophilus I 1 0 1 100.0 0.0
Bacillus stearothermophilus II 4 0 4 100.0 0.0
Bacillus subtilis 3 0 3 100.0 0.0
Bacillus spp. 1 0 1 100.0 0.0
Candida albicans 7 0 7 100.0 0.0
Eenterococcus asacchrolyticus 1 0 1 100.0 0.0
Eenterococcus avium 13 6 7 53.8 46.2
Eenterococcus caecorum 32 21 11 34.4 65.6
Eenterococcus casseliflavus 32 26 6 18.8 81.3
Eenterococcus dispar 29 26 3 10.3 89.7
Eenterococcus durans 2 1 1 50.0 50.0
Eenterococcus faecalis 13 8 5 38.5 61.5
Eenterococcus faecium 11 11 0 0.0 100.0
Eenterococcus gallinarum 16 13 3 18.8 81.3
Eenterococcus hirae 42 33 9 21.4 78.6
Eenterococcus malodoratus 3 3 0 0.0 100.0
Eenterococcus mundatii 7 4 3 42.9 57.1
Eenterococcus raffinosus 5 5 0 0.0 100.0
Eenterococcus solitarius 1 0 1 100.0 0.0
Enterococcus spp. 6 0 6 100.0 0.0
Lactobacillus acidophilus 1 0 1 100.0 0.0
Micrococcus agilis 3 1 2 66.7 33.3
Penicillium spp. 3 0 3 100.0 0.0
Staphylococcus aureus 13 8 5 38.5 61.5
Staphylococcus epidermidis 2 0 2 100.0 0.0
Staphylococcus sciuri 23 19 4 17.4 82.6
Staphylococcus xylosus 2 2 0 0.0 100.0
Staphylococcus spp. 3 1 2 66.7 33.3
Streptococcus gallinarum 2 1 1 50.0 50.0
Streptococcus milleri 3 3 0 0.0 100.0
Streptococcus agalactiae 1 0 1 100.0 0.0
Streptococcus alactolyticus 1 1 0 0.0 100.0
Streptococcus caseolyticus 1 1 0 0.0 100.0
Streptococcus mobilis 21 8 13 61.9 38.1
Streptococcus spp. 3 1 2 66.7 33.3
232 Int. Res. J. Pharm. Pharmacol
Table 4. Minimum inhibitory concentration of lemongrass oil for different microbes
Type of strain Strain
number
Results with disc
diffusion method
Minimum inhibitory
concentration of LGO in µg/ ml
Candida albicans CV1PD Sensitive 1
ABY42 Sensitive 1
Enterococcus faecalis SV7 Sensitive 16
SV20 Sensitive 32
E31 Resistant 64
CV14NC Resistant 128
Streptococcus mobilis SV11 Sensitive 16
SV27NC Sensitive 32
SV12 Resistant 64
SV36NC Resistant 64
Staphylococcus aureus SK10S2 Sensitive 1
SK5S1 Sensitive 8
SK6S1 Resistant 64
SKE111 Resistant 64
Bacillus coagulans CB1 Sensitive 1
CB6 Sensitive 4
A12 Resistant 64
B17 Resistant 64
Klebsiella pneumoniae CP62 Sensitive 16
M10 Sensitive 32
LT81 Resistant 64
LT121 Resistant 124
Edwardsiella tarda 26P Sensitive 4
1BCY Sensitive 32
56LT1 Resistant 128
59LT3 Resistant 64
Escherichia coli E382
(Control)
Sensitive 1
C91 Sensitive 8
P82 Resistant 128
P86 Resistant 128
mold strains were confirmed according to Holt et al.
(1986), Barnett et al. (2000) and Raper and Fennell
(1977), respectively. A reference strain of E. coli
(E382), received from National Salmonella Centre,
IVRI, Izatnagar, Bareilly, India, was sensitive to all
antimicrobial drugs and was used as control to
determine the MIC of LGO.
Determination of Antimicrobial activity of LGO
The antibacterial activity was determined by disk
diffusion method and minimum inhibitory concentration
(MIC) determination assays methods of National
Committee for Clinical Laboratory Standards (NCCLS)
and Clinical and Laboratory Standards Institute (CLSI).
For disk diffusion test, sterile disks of five mm diameter
were soaked in methanolic solution of LGO and dried at
room temperature to contain 50µg of the oil. Mueller
Hinton agar (MHA; Hi-Media, Mumbai) plates were
swabbed with 6-8 hour growth of test bacteria in tryptic
soy broth (TSB, Hi-Media) medium or with overnight
Sabrauds’ broth (Hi-Media Mumbai) growth of yeast
and mold strains, plates were allowed to dry. LGO discs
with standard positive control disc (50µg mercuric
chloride) and negative control disc (disc soaked in
methanol and dried) was placed on the MHA plate.
Plates were incubated overnight at 37°C for bacteria
and for 48-72 hours at 2C for yeast/fungi, the
inhibition zone around discs was measured in mm.
To determine the effect of growth condition on disc
diffusion assay, 8 strains of Enterococcus avium were
tested under aerobic and microaerobic growth
conditions simultaneously. For microaerophilic
condition, plates were incubated in an anaerobic culture
jar (Merck, Germany) using gas generating kit,
Anaeocult® C (Merck) Cat No. 1.16275.0001. Plates
were incubated for 24 h and zone of inhibition was
recorded as for the aerobic plates.
For determination of MIC of selected LGO disc
sensitive and resistant strains (Table 4) of Klebsiella
pneumoniae (CP62, M10, LT 81, LT121), Escherichia
coli (E382, C91, P82, P86), Edwardsiella tarda (26P,
1BCY, 56LT1, 59LT3), Bacillus coagulans (CB1, CB6,
A12, B17), Staphylococcus aureus (SK10S2, SK5S1,
SK6S1, SKE111), Streptococcus mobilis (SV11,
SV27NC, SV12, SV36NC), Enterococcus faecalis (SV7,
SV20, E31, CV14NC) and Candida albicans (CV1PD,
ABY42), agar dilution susceptibility test was performed
based on modified method of NCCLS and CLSI. Briefly,
LGO dissolved in sterilized dimethyl-sulphoxide
(DMSO; 1024 µg /ml) was taken as standard and two
fold dilutions were made to achieve 256, 128, 64, 32,
16, 8, 4, 2 and 1 µg /ml concentration of essential oil in
molten (at 450C) MHA. Plates were poured and after
solidification, the plates were spot inoculated with loop-
full (2 µl) of overnight grown bacterial/ yeast cultures.
The test was carried out in triplicates and plates were
incubated overnight at 37°C for bacteria and 22°C for
yeast. After 18 to 24 hours, the MIC was determined.
To determine that LGO is either microbiostatic or
microbicidal, LGO dissolved in sterilized dimethyl-
sulphoxide (DMSO; 100 mg /ml) was mixed with
sterilized normal saline solution (NSS) or with brain
hear infusion (BHI) medium (Hi-Media) to the final
concentration of 1 mg/ ml and 0.01 mg/ ml. In LGO
containing BHI medium or NSS, washed (with NSS)
cells of overnight grown bacteria (S. aureus SKE111, E.
coli 382) and yeast (C. albicans, ABY42) were added at
concentration of 42000 colony forming units per ml.
Aliquots were drawn at an interval of 1 min for first 10
min and then at an hour interval for 30 h. Aliquots were
plated in triplicate for counting the cfu/ ml after serial
dilution in NSS. All tests were repeated thrice for
conformity.
RESULTS
Results of antimicrobial activity of LGO using disc
diffusion method revealed that 38.2% of 1114 strains of
different microbes were sensitive. All molds (Apergillus
spp., 11; Penicillium spp., 3), yeasts (Candida albicans,
7), Lactobacillus acidophilus (1) and Morganella
morganii (3) strains tested were sensitive to LGO
(Table. 1) while for other bacteria results varied with
species of the microbes (Table 2, 3). The effect of
reduced oxygen and enhanced carbon-di-oxide in
incubating chamber was also evident, of the 8
Enterococcus avium strains tested simultaneously
under aerobic and microaerobic conditions. Only three
stains were resistant under aerobic incubation while six
turned resistant under microaerobic incubation. Zone of
inhibition also reduced significantly under microaerobic
growth conditions.
Among the Gram negative bacteria there was a wide
variation in sensitivity of bacterial strains to LGO discs
among different genera and different species of a genus
(Table 2). Although 78% aeromonads were sensitive to
LGO, species wise analysis (Table 2) revealed that all
strains of A. media (9), A. schubertii (8), A. sobria (3),
A. salmonicida ssp. smithia (1), majority of the strains of
A. caviae (10 of 12), A. hydrophila (15 of 18), A. veronii
(13 of 14), A. salmonicida ssp. salmonicida (3 of 5)
were sensitive to LGO discs. However, majority of the
Singh et al. 233
strains of A. salmonicida ssp. achromogenes (2 of 3)
and A. eucranophila (10 of 18) were resistant to LGO.
Many of the pseudomonads (46.4%) were sensitive but
all strains of P. aeruginosa and P. fluorescens were
resistant to LGO.
Among the members of Enterobacteriaceae majority
of Edwardsiella (73.9%), and 50% of Budvicia aquatica
and Leminorella ghirmontii strains were sensitive to
LGO (Table 3). On the other hand, all Hafnea alvei (4),
Laclercia adecarboxylata (1), Xenorhabdus
luminescens (1) and majority of Salmonella enterica
(98.3% of 59), Citrobacter spp. (93.7% of 95),
Providencia spp. and Kluyvera cryocrescens (83.3% of
6 each), Enterobacter spp. (78.2% of 55), Proteus spp.
(78% of 41), Escherichia spp. (77.7% of 112), Serratia
spp., and Erwinia ananas (75% of 12 each), Pragia
fontium (70.6% of 17), and Klebsiella spp. (62.7% of
110) strains were resistant to lemongrass oil (Table 1).
The only strains of Edwardsiella hoshiniae and 77.3%
of 22 E. tarda were sensitive to LGO however,
excepting a few strains of Enterobacter agglomerans
(39.1% of 23) and two of the three strains of E.
amnigenus group II along with one unidentified
Enterobacter strain all Enterobacter strains belonging to
other six species (Table 2) were resistant to LGO.
Out of 112 strains of Escherichia, 87 were resistant to
LGO but 50% of E. fergusonii strains were sensitive. In
contrast, 19.8% of E. coli, 33.3% of E. blattae and one
of the two strains of E. vulneris were resistant to LGO.
Among Klebsiella species strains, strains of K.
pneumoniae were the most sensitive (40% of 95) while
majority of K. terrigena (5 of 6) and K. oxytoca (7 of 9)
were resistant to LGO. Similarly, of the 41 strains of
four species of Proteus, 32 were resistant to LGO
without much variation among different species except
the only strain tested of P. myxofaciens (Table 2). On
the same lines, out of 59 salmonellae 58 were resistant
to LGO, the only one sensitive strain belonged to S.
enterica ssp. indica, none of the S. enterica ssp.
houtenae and S. enterica ssp. salamae strain was
sensitive to LGO. All five strains of Providencia rettgeri
but no strains of P. haembachii were resistant to LGO.
All Serratia including S. fonticola, S. marcescens, S.
odorifera and S. plymuthica strains were resistant to
LGO but all the three strains belonging to S. rubidiae
were sensitive to LGO. Similarly, only 92.3% strains of
Citrobacter freundii and all strains of C. diversus and C.
amalonaticus were resistant to LGO discs (Table 2).
Similar to Gram negative strains, variation in LGO
sensitivity pattern was evident in Gram positive bacteria
too (Table 3). Most of the Bacillus species strains
(84.3%) and many of the streptococci (53.1%) were
sensitive to LGO while majority of enterococci (73.7%)
and staphylococci (69.8%) were resistant. None of the
strains belonging to 11 Bacillus spp. (Table 3) was
resistant to LGO; however, a few strains of B. brevis
(25%), B. coagulans (19.6%), B. pentothenticus (6.3%)
and all six B. licheniformis strains were resistant to LGO
discs. Out of 213 strains of enterococci, 157 were
resistant to LGO including all strains of E. raffinosus (5),
E. faecium (11), and E. malodoratus (3) and majority of
234 Int. Res. J. Pharm. Pharmacol
the strains of E. caseslliflavus (26 of 32), E. dispar (26
of 29), E. gallinarum (13 of 16) and E. hirae (33 of 42)
were resistant but all the unidentified enterococci and
sole strains of E. asacchrolyticus and E. solitarus were
sensitive to LGO. Both the strains of Staphylococcus
xylosus were resistant but both the strains of S.
epidermidis were sensitive; however, most of the strains
of S. sciuri (82.6% of 23) and S. aureus (61.5% of 13)
were resistant to LGO. Majority of the strains of
streptococci were sensitive to LGO including all strains
of S. agalactiae, most of the S. mobilis (61.9%) and
66.7 % of non-classified streptococcal strains; however,
no strains of S. milleri, S. alactolyticus and S.
caseolyticus was sensitive to LGO.
Determination of MIC through agar dilution method
against resistant and sensitive strains of Klebsiella
pneumoniae (CP62, M10, LT 81, LTLT121),
Escherichia coli (E382, C91, P82, P86), Edwardsiella
tarda (26P, 1BCY, 56LT1, 59LT3), Bacillus coagulans
(CB1, CB6, A12, B17), Staphylococcus aureus
(SK10S2, SK5S1, SK6S1, SKE111), Streptococcus
mobilis (SV11, SV27NC, SV12, SV36NC),
Enterococcus faecalis (SV7, SV20, E31, CV14NC) and
Candida albicans (CV1PD, ABY42) revealed (Table 4)
that all the strains tested sensitive to LGO (with disc
diffusion method) had MIC 32 µg/ ml while those
resistant had MIC 64 µg/ ml. Both the C. albicans
strain had MIC 1 µg/ ml while for bacterial strains
sensitive to LGO discs it ranged from 1 µg/ ml to 32 µg/
ml.
Studies to determine that the action of LGO on
microbes is either microbiostatic or microbicidal, on
cultures of LGO resistant S. aureus (SKE111) and LGO
sensitive E. coli (E382) and C. albicans (ABY42),
revealed that LGO was more active while bacteria were
in NSS than they were in BHI. Both the sensitive
cultures were killed within a minute while resistant S.
aureus (SKE111) was detected even after 5 minutes
but not at 10 minute of exposure of microbes to 1mg /
ml in NSS, indicating the microbicidal action of LGO. On
the other hand in BHI, LGO sensitive bacteria could be
detected for 6 h and resistant strains was present up to
18 h of exposure. However, when cultures were
suspended in NSS containing 0.01 mg/ ml of LGO it
took 18 h to kill C. albicans and 24 h for killing E. coli
strains but had no bactericidal effect on S. aureus. In
BHI, LGO at 0.01 mg/ ml level was only bacteriostatic
for E. coli (E382) and C. albicans (ABY42) while
number of S. aureus (SKE111) started to increase after
a bacteriostatic period of 3 h.
DISCUSSION
Of the 1114 strains of microbes tested for sensitivity to
LGO discs (50µg LGO/ disc), 38.2% were sensitive and
clear zone of growth inhibition (8 mm) was evident.
Our observations revealed that all 14 fungal
(Aspergillus spp., Penicillium species) and 7 yeast (C.
albicans) strains were sensitive to LGO, and our
findings are in concurrence to earlier reports (Abd-El
Fattah et al., 2010; Abu-Seif et al., 2009; da Silva et al.,
2008). Antifungal activity of LGO is proved to be due to
its flavonoids (Pratt and Hudson, 1991; Nieto et al.,
1993; Abu-Seif, et al., 2009) and phenolic compounds
(Abu-seif et al., 2009). Due to LGO’s antifungal activity
it has been claimed as an effective fungi control agent
suitable for protection of food (Patker et al., 1993).
Although in earlier studies antimicrobial activity of LGO
has been reported higher against bacteria than fungi
and yeast (Helal et al., 2006) with a MIC for yeasts ~2
µl/ ml, in our study with C. albicans MIC was
determined to be 1µg/ ml, it might be due to use of
different strains in earlier studies (Botrytis cinerea)
which might be more resistant than the strains of C.
albicans. However we have not tested fungal strains for
MIC of LGO but by analogy (that all strains tested
sensitive with disc diffusion assay had MIC not more
than 32 µg/ ml) we may predict that the isolates of
Penicillium, A. flavus and A. niger also had MIC 32 µg/
ml which is much lower than that reported earlier 1.5 µl/
ml (Helal et al., 2006), it may be explained either on the
basis of strain variation or the differences in LGO
extracted from lemongrass in Nagaland and elsewhere.
LGO was effective against several Gram positive and
Gram negative bacteria but its effectiveness cannot be
generalized beyond certain levels of concentration.
Observations revealed that all bacterial strains of a
genus may not be equally sensitive as 115 Bacillus
species strains (84.3%) and many of the streptococci
(53.1%) were sensitive to LGO while majority of
enterococci (73.7%) and staphylococci (69.8%) were
resistant. Similarly among Gram negative bacteria 78%
aeromonads, 73.9% Edwardsiella (73.9%) and 50% of
Budvicia aquatica and Leminorella ghirmontii strains
were sensitive to LGO while majority of Salmonella
enterica (98.3% of 59), Citrobacter spp. (93.7% of 95),
Providencia spp. and Kluyvera cryocrescens (83.3% of
6 each), Enterobacter spp. (78.2% of 55), Proteus spp.
(78% of 41), Escherichia spp. (77.7% of 112), Serratia
spp., and Erwinia ananas (75% of 12 each), Pragia
fontium (70.6% of 17), and Klebsiella spp. (62.7% of
110) strains were resistant. But this resistance or
sensitiveness is comparative and results vary with the
concentration of LGO used. At higher concentration one
may not find any strain resistant but at lower levels of
LGO even the most sensitive may appear as resistant.
Therefore we need to standardize the cut off limit for the
concentration according to the tolerance of LGO. In
earlier studies LGO is reported to possess potent
bactericidal activity against Gram positive and Gram
negative bacteria (Chao and Young, 2000; Onawunmi,
1989; Syed et al., 1995; Alam et al., 1994; Sharma et
al., 2003; Saikia et al., 1999) but in most cases the
concentration used to kill the bacteria was too high (1 to
100mg/ml) varying for different organisms (Ferdinand et
al., 2009; Sue et al., 2008; Ohno et al., 2003). In our
study, at 1mg/ ml concentration all the microbes tested
including the resistant S. aureus were killed within 5
minutes while only those which were sensitive with disc
diffusion method could be eliminated at 10 µg/ ml
concentration. Similar results have been reported earlier
for Hemophillus influenzae, S. pneumoniae, S.
pyogenes and S. aureus, inhibited at <12.5 µg/ ml, and
E. coli, inhibited at at 100 µg/ ml concentration (Inouye
et al., 2001).
Further, testing medium might also lead to variation in
interpretation of sensitivity (Lalitha, 2004), in this study
almost 100 fold higher concentration of LGO was
needed to induce the same antibacterial effect when
BHI was used as the medium instead of NSS.
Therefore, the confusion regarding antimicrobial activity
among different study in relation to MIC might be due to
difference in the medium and the method used.
Moreover, variation in disc concentration of herbal oil in
different studies might be source of confusion while
interpreting the results. Therefore, for uniformity a
standard feasible (biologically achievable) concentration
should be used in discs to determine sensitivity of
different herbs, and 50 µg / disc concentration is quite
feasible option to explore the affectivity of probable
antimicrobial herbs.
The effect of oxygen deficient and CO2 rich
environment as expected under in vivo conditions was
highly significant in reduction of the sensitivity of eight
E. avium strains tested, indicating that the results of
antimicrobial drug sensitivity particularly for LGO results
obtained by general method of disc diffusion might lead
to wrong perception of affectivity of the drug. The
observations are in concurrence to reduction in
antimicrobial activity of tobramycin, amikacin, and
aztreonam under anaerobic conditions (King et al.,
2010). However, more studies are required to
understand effect of microaerophilic growth conditions
on sensitivity of microbes and to have a broad idea
about utility of general diffusion assay for facultative
anaerobes and microaerophilic microbes.
It can be concluded from the observations that LGO is
bactericidal and fungicidal at higher concentration (1mg/
ml) while bacteriostatic at lower concentrations (<10µg/
ml). Variation in LGO activity (MIC) on different strains
of bacteria is inevitable as for most of the
antimicrobials. All microbes are not equally susceptible
to LGO as Bacillus spp. and streptococci among Gram
positive and aeromonads and E. tarda among Gram
negative bacteria are comparatively more susceptible to
LGO than most of the other potentially pathogenic
bacteria. Although number of yeast and mold strains
was less (21) in the study, their uniform sensitivity was
indicative of wide spectrum of LGO’s antimicrobial
action.
ACKNOWLEDGEMENTS
Authors are thankful to Naga Fragrance Pvt. Ltd.
Dimapur, for providing LGO free of cost as and when
required. Authors also thankful to Joint Director,
Director of the ICAR Research Centre for NEH Region
and Director NRC on Mithun, Jharnapani, Nagaland, for
kindly providing the funds and facilities to conduct this
study.
Singh et al. 235
REFERENCES
Abd-El Fattah SM, Hassan ASY, Bayoum HM, Eissa HA (2010). The
use of lemongrass extracts as antimicrobial and food additive
potential in yoghurt. J. Am. Sci. 6: 582-594.
Abu-Seif FA, Abdel-Fattah ShM, Abo Sreia YH, Shaaban HA,
Ramadan MM (2009). Antifungal properties of some medicinal
plants against undesirable and mycotoxin-producing fungi. J. Agric.
Mansuora Univ. 34: 1745-1756.
Aibinu I, Adenipekun T, Adelowowtan T, Oguns anya T, Odugbemi T
(2007). Evaluation of the antimicrobial properties of different parts
of Citrus aurantifolia (lime fruit) as used locally. Afr. J. Tradit. CAM.
2: 185-190.
Alam K, Agua T, Maren H, Taies R, Rao KS, Burrows I, Hubber ME,
Rali T (1994). Preliminary screening of seaweeds, seagrass and
lemongrass oil from Papua New G uinea for antimicrobial and
antifungal activity. International J. Pharmacogn. 32: 396-399.
Alippi MA, Ringuelet JA, Cerimele EL, Re MS, Henning CP (1996).
Antimicrobial activity of some essential oil against Paenibacillus
larvae, the c ausal organism of Americal foulbrood disease. J Herbs
Spices Med. Plants. 4: 9-16.
Ali-Shtayeh MS, Abu Ghdeib SI (1999). Antimyc otic activity of twenty-
two plants used in f olkloric medicine in the Palestinian area for the
treatment of skin diseases suggestive of dermatophyte infection.
Mycoses. 42: 665-672.
Barnett JA, Payne RW , Yarrow D (2000). Yeasts: characteristics and
identification. 3rd ed. Cambridge University Press. Cambridge, U.K.
Brian TS, Ikhlas AK (2002). Comparison of extraction methods for
marker compounds in the essential oil of lemongrass by GC. J.
Agric. Food Chem. 50: 1345-1349.
Chao SC, Young DG (2000). Screening of antibacterial activity of
essential oils on s elected bacteria, fungi and viruses. J. Essent. Oil
Res. 12: 630-649.
Clinical and Laboratory Standards Institute (2008). Performance
standards for antimicrobial susceptibility testing. Eighteenth
informational supplement CLSI document M100-S18, Wayne.
Clinical and Laboratory Standards Institute (2009). Method for dilution
antimicrobial susceptibility tests for bacterial that grow aerobically;
approved standard - Eighth Edition. CLSI document M07-A8,
Wayne.
da Silva CdB, Guterres SS, Weisheimer V, Schapoval EES (2008).
Antifungal activity of the lemongrass oil and citral against Candida
spp. Braz. J. Infect. Dis. 12: 1-14.
Depken KL (2011). Properties of Lemon Grass.
http://www.ehow.com/about_5382246_properties-lemon-
grass.html.
Ferdinand FJ, Esther U, Tayo A, Omotoyin A (2009). Evaluation of the
antimicrobial properties of unripe banana (Musa sapientum L.),
lemon grass (Cymbopogon citratus S.) and turmeric (Curcuma
longa L.) on pathogens. Afr. J. Biotechnol. 8: 1176-1182.
Ghani KU, Saeed A, Alam AT (1997). Indusyonic Medicine;
Traditional Medicine of Herbal, Animal and Mineral Origin in
Pakistan. University of Karachi.
Helal GA, Sarhan MM, Abu Shahla ANK, El-Khai EKA (2006).
Antimicrobial activity of some essential oils against microorganisms
deteriorating fruit juices. Mycobiol. 34: 219-229.
Holt JG, Sneath PHA, Mair MS, Sharpee ME (1986). Bergey,s manual
of systematic bacteriology, vol. 2. Williams & Wilkins, 428 east
Preston Street, Baltemore, MD 211202, U.S.A.
Huynh KP, Maridable J, Gaspillo P, Hasika M, Malaluan R, Kawasaki
J (2008). Ess ential oil from lemongrass extracted by supercritical
carbon dioxide and steam distillation. The Phillippine Agric. Sci. 91:
36-41.
Inouye S, Takizava T, Yamaguchi H (2001). Antibacterial activity of
essential oils and their major constituents against respiratory tract
pathogens by gaseous contact. J. Antimicrob. Chemother. 47: 565-
573.
Cheel J, Theoduloz C, Rodríguez J, Schmeda-Hirschmann G (2005).
Free radical scavengers and antioxidants from Lemongrass
(Cymbopogon citratus (DC.) Stapf.). J. Agric. Food Chem. 53:
2511-2517.
King P, Citron DM, Griffith DC, Lomovskaya O, Dudley MN (2010).
Effect of oxygen limitation on the in vitro activity of levofloxacin and
other antibiotics administered by the aerosol route against
Pseudomonas aeruginosa from cystic fibrosis patients. Diagnostic
236 Int. Res. J. Pharm. Pharmacol
Microbiol. Infect. Dis. 66: 181-186.
Lalitha MK (2004). Manual on Antimicrobial Susc eptibility Testing.
Department of Microbiology, Christian Medical College, Vellore,
Tamil Nadu, India. (www.ijmm.org/documents/Antimicrobial.doc)
Lawless J (1995). Illustrated Encyclopedia of Essential Oil : The
Complete Guide to use of Oil in Aromatheraphy and Herbalism.
Element Books: Rockport, MA, pp 56-67.
National Committee f or Clinical Laboratory Standards (2003).
Methods for dilution antimicrobial susceptibility tests for bacteria
that grow aerobically. A pproved Standard - NCCLS document M7-
A6, Wayne.
Nieto S, Gorrido A, Ssanhaeza J, Loyala LA, Marale G, Leighton FG,
Valenzula A (1993). Flavonoid as stabilizers fish oil: an alternative
to synthetic antioxidants. J. Am. Oil Chem. Soc. 70: 773-778.
Odugbemi T (2006). Medicinal plants as antimicrobials In: Outline and
pictures of Medicinal plants from Nigeria. University of Lagos press.
pp. 53-64.
Ohno T, Kita M, Yamaoka Y, Imamura S, Yamamoto T, Mitsufuji S,
Kodama T, Kashima K, Imanishi I (2003) Antimicrobial activity of
essential oils against Helicobacter pylori. J. Helicobacter. 8: 207-
215.
Onawunmi GO (1989). Evaluation of the antimicrobial activity of citral.
Lett. Appl. Microbiol. 9: 105-108
Patker KI, Usha CM, Shetty SH, Paster N, Lacey J (1993). Effect of
spice oils on growth and aflatoxin B1 production by Aspergillus
flavus. Lett. Appl. Microbiol. 17: 49-51.
Pearson O (2010). The Antibacterial Properties of Essential Oils.
http://www.livestrong.com/article/168697-the-antibacterial-
properties-of-essential-oils/# ixzz1W7u9hn6K.
Pratt DE, Hudson BJF (1991). Antioxidant activity of phenolic
compounds in meat model systems. In phenol compounds in f ood
and their effects on health. AC S ymposium S erieus 506; American
Chemical Society, 1990. Washington, DC, 1991; pp 214-222.
Raper K B, Fennell DI (1977). The genus Aspergillus Robert E.
Krieger Publishing Company. Huntington, New York.
Saify ZS, Mustaq N, Noor F, Naqvi SBS, Mardi SA (2000).
Antimicrobial activity of some commonly used herbs. Pakistan J.
Pharm. Sci. 13: 1-3.
Saikia D, Shantha Kumar TR, Kaliol AP, Khanuja SPS (1999).
Comparative bioevaluation of essential oil of three species of
Cymbopogon for their antimicrobial activities. J. Med. Arom. Plant
Sci. 21:24.
Sharma A, Tayung K, Baruah AKS, Sharma TC (2003). Antibacterial
activity of lemongrass [Cymbopogon fleuosus (Steud) W ats]
inflorescence oil. Indian Perfum. 47:389-393.
Sue C, Gary Y, Craig O, Karen N (2008). Inhibition of methicillin-
resistant Staphylococcus aureus (MRSA) by essential oils. Flavour
Frag. J. 23: 444–449.
Syed M, Qumar S, Riaz M, Choudhary FM (1995). Essential oil of the
family Gramineae with antimicrobial activity part II. The
antimicrobial activity of a local variety of Cymbopogon citratus and
its dependence of storage. Pakistan J. Sci. Ind. Res. 38:146-148.
Ushimaru PI, Mariama TN, Luiz C, Di Luciano B, Ary FJ (2007).
Antibacterial activity of medicinal plant extract. Braz. J. Microbial.
38:717-719.
... The resistance against plant medication in numerous clinical/non-clinical isolates of pathogens has been evidenced more recently from animal clinical isolates. However, this sensitivity or resistance is comparative and varied results were observed with different drug concentrations used [148]. In studies on resistance against LGO and different herbal medication, variable levels of MIC were shown [128] depending upon microbial species tested or inside similar species among completely variable strains, which suggests that microorganism have a mechanism to beat the germicidal concentration of plant medication conjointly. ...
... However, studies reported that a number of isolates, such as E. coli, P. aeruginosa, K. pneumoniae, C. albicans, and E. coli from nosocomial infections and C. albicans, K. Pneumonia, and E. coli isolated from the community were resistant to herbal medication. Singh et al. (2011) [148] reported that many microorganism strains derived from completely different clinical complications from post-mortem cases and in animals were resistant to lemongrass oil. High resistance was observed in microorganism strains from gecko origin towards antimicrobials of herbal origin. ...
... However, studies reported that a number of isolates, such as E. coli, P. aeruginosa, K. pneumoniae, C. albicans, and E. coli from nosocomial infections and C. albicans, K. Pneumonia, and E. coli isolated from the community were resistant to herbal medication. Singh et al. (2011) [148] reported that many microorganism strains derived from completely different clinical complications from post-mortem cases and in animals were resistant to lemongrass oil. High resistance was observed in microorganism strains from gecko origin towards antimicrobials of herbal origin. ...
Article
Full-text available
Plants, being the significant and natural source of medication for humankind against several ailments with characteristic substances hidden on them, have been recognized for many centuries. Accessibility of various methodologies for the revelation of therapeutically characteristic items has opened new avenues to redefine plants as the best reservoirs of new structural types. The role of plant metabolites to hinder the development and movement of pathogenic microbes is cherished. Production of extended-spectrum β-lactamases is an amazing tolerance mechanism that hinders the antibacterial treatment of infections caused by Gram-negative bacteria and is a serious problem for the current antimicrobial compounds. The exploration of the invention from sources of plant metabolites gives sustenance against the concern of the development of resistant pathogens. Essential oils are volatile, natural, complex compounds described by a solid odor and are framed by aromatic plants as secondary metabolites. The bioactive properties of essential oils are commonly controlled by the characteristic compounds present in them. They have been commonly utilized for bactericidal, virucidal, fungicidal, antiparasitic, insecticidal, medicinal, and antioxidant applications. Alkaloids are plant secondary metabolites that have appeared to have strong pharmacological properties. The impact of alkaloids from Callistemon citrinus and Vernonia adoensis leaves on bacterial development and efflux pump activity was assessed on Pseudomonas aeruginosa. Plant-derived chemicals may have direct antibacterial activity and/or indirect antibacterial activity as antibiotic resistance modifying agents, increasing the efficiency of antibiotics when used in combination. The thorough screening of plant-derived bioactive chemicals as resistance-modifying agents, including those that can act synergistically with antibiotics, is a viable method to overcome bacterial resistance. The synergistic assessment studies with the plant extract/essential oil and the antibiotic compounds is essential with a target for achieving a redesigned model with sustainable effects which are appreciably noticeable in specific sites of the plants compared to the entirety of their individual parts.
... for ampicillin ( was determined by disc diffusion assay using discs containing 1µL of the test herbal compound [12]. For all isolates, resistograms were prepared and compared to determine the similarity among different isolates. ...
... Besides, MDR Klebsiella pneumoniae ssp. [28], resistance to some of the herbal antimicrobials is not uncommon [6,12] and is said be emerging among bacteria causing infections in animals [29]. ...
Article
Full-text available
Abortions are multietiological disorders of pregnancy interfering with reproduction, and bacteria are often the most common cause of in-utero death of foetii. The study was conducted to understand the bacteria associated with abortion and foetal death in big cats. Bacteriological analysis of aborted foetii samples (heart blood, stomach contents, liver, spleen, kidneys and lunges etc.) from lions (two) and tigers (four) revealed presence of bacteria of 11 different species viz.
... Besides, all the isolates were also tested for their susceptibility to ajowan (Trachyspermum ammi) oil (AO), betel (Piper betel) leaf of herbal compound/oil were prepared as described earlier and stored in sealed vials at 4 o C till used for disc diffusion assays [28]. ...
Article
Full-text available
Raw Neem (Azadirachta indica) leaves' chewing is an often-recommended healthy practice in India, but little is understood about the microbial quality of the leaves chewed. This study was conducted to analyze the presence of potential microbiological hazards associated with Neem leaves. It was assessed through isolation and antimicrobial resistance (A.M.R.) profiling of different aerobically growing bacteria using standard bacteriological methods. A total of 110 samples of Neem leaves collected from four localities (IVRI = 62, CARI = 10, Mahanagar = 18, and Suncity = 20) analyzed yielded 357 bacterial isolates belonging to more than 63 species of 24 genera. Isolation of Gram-negative bacteria from samples of IVRI and CARI was significantly more frequent (p, < 0.05) than those from Mahanagar and Suncity, while the picture was in reverse for Gram-positive bacteria isolates. The most prevalent potentially pathogenic bacteria included Enterobacter (Pantoea) agglomerans detected in 37 samples, followed by Hafnia alvei (20), Escherichia coli (11), Serratia marcescens (8), Bacillus cereus (7), Raoultella terrigena (7), Serratia odorifera (7), Aeromonas bestiarum (4), Enterococcus faecium (2), Klebsiella oxytoca (2), K. pneumoniae (1), Pseudomonas aeruginosa (2), Acinetobacter ewofflii (1), Aeromonas caviae (1), Proteus mirabilis (1), Stenotrophomonas multophilia (1), and Pseudomonas pseudoalcaligenes (1). In 26 samples, carbapenem-resistant (CR) and 72 samples, extended-spectrum β-lactamase (ESBL) producing bacteria were detected. Herbal antimicrobial drug resistance was also seen in a large number of bacterial isolates. The study indicated that A. indica leaves may be harboring potentially pathogenic multiple drug-resistant bacteria, which may harm the health of leaves consumers. Therefore, it may be suggested that a fresh A. indica leaves should only be consumed after proper cleansing and decontamination.
... Lemongrass oil has been reported to have antimicrobial activity against E. coli and S. aureus (Leimann et al., 2009), S. mutans (Chaudhari et al., 2012), B. cerveius (Premathilake et al., 2018) and antifungal activity against Colletotricum truncatum, Fusarium spp., Penicillium spp., Crysosporium spp (Premathilake et al., 2018), Ascosphaera apis and Pseudogymnoascus destructans (Gabriel et al., 2018). However, Singh et al. (2011) and Shendurse et al. (2021) reported that P. aeruginosa was resistant to lemongrass oil, whereas Unachukwu et al. (2017) reported that lemongrass oil could weakly inhibit S. pyogenes but could not inhibit P. aeruginosa. This might explain why addition of lemongrass oil in this research did not affect the antimicrobial activity of guava leaf hard candy. ...
... Antimicrobial sensitivity of isolates was determined using disc diffusion method following CLSI [10] Resins & Gums, Namkum, Ranchi, India. The 6 mm discs loaded with 1µL of herbal compound/ oil were used for determining sensitivity of isolates through disc diffusion assay as described earlier [11]. Similar to MAR index the herabl MAR (HMAR) indices were also determined for all the isolates. ...
Article
Full-text available
The study was conducted to evaluate the microbial quality of water supplies in Bareilly city and nearby villages. A total of 111 samples comprising community pond water (45), drinking water (36), water tap handle swabs (city, 23), and sewage water (7, city) were analysed. A total of 363 bacterial isolates belonging to 25 genera were identified of which 71.3%, 47.7%, and 30% isolates had multiple drug resistance, carbapenem resistance, and produced extended-spectrum-β-lactamases (ESBL), respectively. Twenty of the 36 drinking water samples had coliforms and 33.3% were positive for Escherichia coli. Besides, 55 samples had ESKAPE bacteria, 43.24% were positive for carbapenem-resistant bacteria (CRB) and 24.3% of samples had carbapenem-resistant Enterobacteriaceae (CRE). In drinking water samples 8.3 % had CRE and 33.3% had CRB. Two third (65.2%) of water faucet (tap) handles in public places had CRBs mostly belonging to the ESKAPE group of pathogens, and 52.2% carried CRE. The community pond water was still the bigger health hazard since 64.4% and 44.4% of samples were positive for CRB and CRE, respectively. The study indicated that community water sources either for drinking or for other purposes in and around Bareilly city were a potential source of MDR, CR and ESBL-producing strains. Keywords: AMR; CRE; Carbapenem-resistance; Community Water; ESBL; MDR
... The minimum inhibitory concentration (MIC) of all bacteria resistant to carbapenems was determined by E-test (BioMerieux) for imipenem [14,15]. All bacterial isolates were also tested against herbal antimicrobials viz., ajowan (Tachyspermum ammi) seed oil, carvacrol, cinnamaldehyde, cinnamon (Cinnamomum zeylanicum) bark oil, citral, holy basil (Ocimum sanctum) oil, lemongrass (Cymbopogon citrates) oil, and thyme (Thymus vulgaris) oil procured from Sigma Aldrich (USA), and Naga Fragrance Ltd, Dimapur using the disc diffusion assay [16], each disc contained 1µL of the test herbal substance. Bacteria resistant to three or more classes of antibiotics or herbal antimicrobials were classified as multiple-drug-resistant (MDR) and multiple herbal drug-resistant (MHDR), respectively. ...
Article
Full-text available
In India, little is understood precisely about the cause of death in big cats in zoos, wild and wildlife sanctuaries. The present study reports the bacterial culturome (culturable bacteria) of the heart blood of leopards (5), lions (9), and tigers (26) found dead in zoos (30) or wildlife sanctuaries (10). From the samples submitted to the Clinical Epidemiological study 145 bacterial (46 Gram-positive and 99 Gram-negative) strains (the group of isolates with a separate identity) belonging to 44 species (19 of G+ve and 25 of G-ve bacteria) were identified. From 17 (12 tiger, 1 leopard, 4 lions) heart blood samples bacteria of the single species were isolated in pure culture indicating cases of septicemia. The most common isolation as single bacteria type was of E. coli (5), followed by isolation of Alcaligenes denitrificans (2), A. feacalis (2), and one each of Acinetobacter calcoaceticus, Bacillus cereus, Paenibacillus macerans, Enterobacter (Pantoea) agglomerans, Pseudomonas aeruginosa, Staphylococcus epidermidis, S. intermedius and Streptococcus pneumoniae. Multiple drug-resistance (MDR) was detected in 73.1% and isolates belonged to 134 resistotypes. There was no significant (p, >0.05) difference in the occurrence of herbal antimicrobial resistance of strains isolated from different animals of different localities. Significantly high probability (p, ≤0.04) of MDR strains and strains resistant to citral, tetracycline, nitrofurantoin, chloramphenicol, and imipenem was recorded in samples from animals that died in wildlife sanctuaries than those died in zoos. Of the 40 carbapenem-resistant (CR) isolates identified from 16 (40.0%) heart blood samples, 21 (all Gram-positive) were negative for MBL and 19 CR strains producing MBL belonged to 8 species of G-ve bacteria. The MIC of imipenem for MBL producer CR isolates ranged between 2 to 32 µg mL-1 while for those not produced MBL MIC ranged from 1.5 to 256 µg mL-1 , all the carbapenem susceptible isolates had imipenem MIC between 0.001 to 1.0 µg mL-1. The study concluded multiplicity of bacteria in the heart blood of big cats died in zoo and wildlife sanctuaries. The presence of multiple bacterial types in 57.5% of samples suggests the need for aseptic and timely collection of blood samples to understand the true etiology of fatality among big cats. Detection of MDR, ESBL, and CR bacteria from 25%, 37.5%, and 40% samples is alarming because of the chances of spreading AMR in the environment from animals suffering from infections with MDR strains and dying in wild.
... Considering the potent antibacterial properties of LO, Singh et al. (2011) have investigated the antimicrobial activity of LO against 1114 microbes from clinical cases, the environment, food, and healthy animals. According to the results of the agar diffusion and inhibition zone assay, 38.2% of all bacteria were susceptible to LO [49,50]. The good antibacterial properties of LO can be explained by the fact that it contains a variety of volatile antimicrobial chemicals, such as geraniol, linalool, citronellal, 1,8-cineole, limonene, citronellol, elemol, methyl heptenone, β-caryophyllene, geranyl acetate, and geranyl formate [51]. ...
Article
To meet the global demand for sustainability aspects, the past few decades have witnessed magnificent evidence in the pursuit of sustainable active food packaging. As part of our contribution, herein, we explored the utilization of chitosan (Ch) modified with Dioscorea hispida (Dh) starch and incorporated with lemongrass essential oil (LO) as an attempt to obtain a novel active packaging formulation of Ch/Dh/LO in food. To obtain the optimum formulation of Ch/Dh/LO, 15 experiments were designed using the Box-Behnken design (BBD) with Ch (1–2% w/v), Dh starch (0.5–1.5% w/v) and LO (0.25–0.75% v/v) against E. coli, S. typhi, S. aureus and S. epidermidis bacteria. The presence of LO caused enhancements in physical, mechanical, and thermal stability, along with the antimicrobial, and antioxidant activity. Additionally, molecular docking and molecular dynamic (MD) simulations of the active compounds in LO against the active site of the FtsA enzyme were provided to unveil the mechanism of antibacterial action. Ultimately, this result suggests hydrogen bonds and hydrophobic interactions are involved between the active compounds in LO and FtsA enzymes. In general, this research provides valuable information that sheds light on the pivotal role of LO in enhancing the mechanical, thermal, and biological properties of sustainable active food packaging-based Ch film.
Article
Full-text available
Phytochemicals are versatile plant secondary metabolites with therapeutic properties. This review explores lemongrass's phytochemistry and pharmacological potential (Cymbopogon) and its impact on gut microbiota. Lemongrass is well-known for its antioxidant, anti-microbial, anti-inflammatory, anti-hypertensive, anti-diabetic, anti-mutagenicity, and anxiolytic properties and its hypoglycemic and hypolipidemic activities. Therefore, it is widely used in pharmaceuticals, food, feed, and cosmetics. Lemongrass contains phenolic metabolites (including phenolic acids, flavonoids, stilbenes, and lignans), terpenoids, and alkaloids, potent bioactive ingredients. Lemongrass is a precious medicinal plant. Furthermore, lemongrass phytochemicals are considered potential agents to improve health by establishing a balanced gut ecosystem. Lemongrass is considered a quintessential food and feed additive at the industrial level since there are no issues with residue or toxins. Lemongrass powder and essential oils are used to modulate the gut ecosystem by generating anti-microbial, anti-inflammatory, and antioxidant responses, increasing the optimum nutrient absorption in the gut system. This review will explore lemongrass's phytochemical, pharmacological, and therapeutic potential.
Article
The spread of bacterial drug resistance has posed a severe threat to public health globally. Here, we cover bacterial resistance to current antibacterial drugs, including traditional herbal medicines, conventional antibiotics, and antimicrobial peptides. We summarize the influence of bacterial drug resistance on global health and its economic burden while highlighting the resistance mechanisms developed by bacteria. Based on the One Health concept, we propose 4A strategies to combat bacterial resistance, including prudent Application of antibacterial agents, Administration, Assays, and Alternatives to antibiotics. Finally, we identify several opportunities and unsolved questions warranting future exploration for combating bacterial resistance, such as predicting genetic bacterial resistance through the use of more effective techniques, surveying both genetic determinants of bacterial resistance and the transmission dynamics of antibiotic resistance genes (ARGs).
Chapter
Medicinal traditional plants are a source of inspiration for the discovery of new bioactive substances. Plant infusions, extracts, and essential oils are known for their diverse biological activity since they are rich in secondary metabolites. The Mediterranean area in general and Lebanon in particular is known for its plant diversity due to its climate and geographical location. This chapter will provide an overview of Lebanese plants with antimicrobial activity. Many of these plants are known for their culinary and traditional medicinal uses for the treatment of different ailments. The main plant families discussed here include Amaryllidaceae, Anacardiaceae, Apiaceae, Asteraceae, Berberidaceae, Cannabaceae, Cistaceae, Lamiaceae, Myrtaceae, Pinaceae, Portulacaceae, Ranunculaceae, Rutaceae, Rosaceae, and others.
Article
This study compares the composition of essential oil extracted from lemongrass leaves and stems using supercritical CO2 (SC CO2) and steam distillation. In the process using SC CO2 extraction in a Supercritical Fluid Extraction System (SFE), the temperature of extraction was varied from 35-50 0C, while the pressure applied was 9.1-11.1 MPa. The flow rate of CO2 to the reactor was maintained at 0.5 m3 h-1. Steam distillation was conducted using a standard bench scale setup. The extracts from both methods were analyzed by gas chromatography - mass spectrometry (GC-MS) and the variations of the composition were reported. The study showed that better oil quality in terms of composition was produced from the air dried raw materials than from direct heat drying. The essential oil extracted from air dried lemongrass leaves by SFE process contained 94.4% citral, 1.14% myrcene and 0.5% limonene, showing a composition similar to the reference standard. In contrast, the oil from the air dried lemongrass stems fell short in terms of purity. SFE was found to be a superior process than steam distillation, producing better quality essential oil containing 90% Citral.
Article
The investigation on the potency of unripe banana (Musa sapientum L.), lemon grass (Cymbopogon citratus S.) and turmeric (Curcuma longa L.) was carried out against pathogens. The formulations were in the powder form as used locally. The antimicrobial activity of these plants was examined using different solvents and efficacy was compared. The solvents were ethanol (70%, v/v) and water. Antimicrobial activity was carried out by the agar well diffusion method. The clinical isolates include aerobic, facultative bacteria namely: Stapyhlococcus aureus ATCC 25921, S. aureus, Salmonella paratyphi, Shigella flexnerii, Escherichia coli ATCC 25922, E. coli, Klebsiella pneumoniae, Bacillus subtilis and Pseudomonas aeruginosa. Crude extracts of the solvents varied in zones of inhibition. All the Gram-positive bacteria (S. aureus, S. aureus ATCC 25921 and B. subtilis) and all Gram-negative bacteria (E. coli ATCC 25922, E. coli, P. aeruginosa, S. paratyphi, S. flexneri and K. pneumonia) were susceptible to ethanolic extracts of unripe banana, lemon grass and turmeric while some namely E. coli ATCC 25922, E. coli, P. aeruginosa and S. flexneri were not susceptible to aqueous extracts of the three medicinal plants. The minimum inhibition concentration (MIC) ranged from 4 - 512 mg/ml while the minimum bactericidal concentration (MBC) ranged from 32 - 512 mg/ml depending on isolates and extracting solvent. Ethanolic extracts showed greater antimicrobial activity than aqueous extracts. The killing rate of the extracts varied. Unripe banana had less than 2 h killing time for S. aureus ATCC 25921, turmeric less than 3 h for E. coli while lemon grass had more than 3 h killing time for S. paratyphi.
Chapter
Nomenclature has been called the handmaid of taxonomy. The need for a stable set of names for living organisms, and rules to regulate them, has been recognized for over a century. The rules are embodied in international codes of nomenclature. There are separate codes for animals, noncultivated plants, cultivated plants, procaryotes, and viruses. But partly because the rules are framed in legalistic language (so as to avoid imprecision), they are often difficult to understand. Useful commentaries are found in Ainsworth and Sneath (1962), Cowan (1978), and Jeffrey (1977). There are proposals for a new universal code for living organisms (see the Proposed BioCode).
Article
The purpose of this study was to examine the inhibitory effect of essential oils against a broad spectrum of microorganisms including bacteria, yeast, molds, and two bacteriophage. The inhibitory effects of 45 oils on eight bacteria (four Gram positive and four Gram negative), two fungi, and one yeast were examined using the disk assay method. Phage inhibition was measured by mixing the oils with a phage suspension, incubating the mixture at 4°C for 24 h, then plating on a lawn of indicator bacteria and assaying for plaque production. Of the oils tested, all oils exhibited inhibition over activity relative to controls. However, a number exhibited only weak inhibition against several gram positive bacteria. Gram negative bacteria were generally more resistant than Gram positive bacteria to oil treatment with Pseudomonas aeruginosa being the most resistant bacteria. Only cinnamon bark (Cinnamomum zeylanicum) and tea tree (Melaleuca alternifolia) oils showed an inhibitory effect against all the test organisms and phage. Coriander oil (Coriandrum sativum) highly inhibited Gram positive bacteria and fungi. Lemongrass (Cymbopogon flexuosus) and Roman chamomile (Chamaemelum nobile) oils showed a high degree of inhibition against both phage types, while 8 oils showed no inhibition against either phage. Angelica (Angelica archangelicd) and pine (Pinus sylvestris) oils inhibited the bacteria, but had no effect on any fungi. Oils that exhibited high antimicrobial properties and the broadest range of inhibition included cinnamon bark (Cinnamomum zeylanicum), lemongrass (Cymbopogon flexuosus), savory (Satureja montana), Roman chamomile (Cbamaemelum nobile), rosewood (Aniba rosaeodora), spearmint (Mentha spicata) and tea tree (Melaleuca alternifolia).
Article
Abstract The methanol and hexane extracts of Halimeda tuna, Enhalus acoroides, Turbinaria ornata, Hormo-physa articulata, Padina sp., Liaqura sp. and Sargassum sp. were tested against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae. Most of the methanol and hexane extracts exhibited antibacterial activity against Gram-positive bacteria. None of the extracts were found to be active against K. pneumoniae and only the methanol extracts exhibited activity against the Gram-negative bacterium P. aeruginosa. The crude ethanol extract of all seaweeds and E. acoroides were tested against the dermatophytes Microsporum canis, Epidermatophy-ton floccosum and Trichophyton rubrum and all of them were found to be inactive. The lemongrass oil was tested against S. aureus, B. subtilis, P. aeruginosa, T. rubrum and Escherichia coli. The oil showed detectable activity against B. subtilis, S. aureus and E. coli.