Shunmugiah Karutha Pandian

Alagappa University, Karaikudi, Tamil Nādu, India

Are you Shunmugiah Karutha Pandian?

Claim your profile

Publications (68)143.52 Total impact

  • Alwar Ramanujam Padmavathi, Shunmugiah Karutha Pandian
    [Show abstract] [Hide abstract]
    ABSTRACT: Coral Associated Bacteria (CAB) (N = 22) isolated from the mucus of the coral Acropora digitifera were screened for biosurfactants using classical screening methods; hemolysis test, lipase production, oil displacement, drop collapse test and emulsifying activity. Six CAB (U7, U9, U10, U13, U14, and U16) were found to produce biosurfactants and were identified by 16S ribosomal RNA gene sequencing as Providencia rettgeri, Psychrobacter sp., Bacillus flexus, Bacillus anthracis, Psychrobacter sp., and Bacillus pumilus respectively. Their cell surface hydrophobicity was determined by Microbial adhesion to hydrocarbon assay and the biosurfactants produced were extracted and characterized by Fourier Transform Infrared spectroscopy. Since the biosurfactants are known for their surface modifying capabilities, antibiofilm activity of positive isolates was evaluated against biofilm forming Pseudomonas aeruginosa ATCC10145. Stability of the active principle exhibiting antibiofilm activity was tested through various temperature treatments ranging from 60 to 100 °C and Proteinase K treatment. CAB isolates U7 and U9 exhibited stable antibiofilm activity even after exposure to higher temperatures which is promising for the development of novel antifouling agents for diverse industrial applications. Further, this is the first report on biosurfactant production by a coral symbiont.
    Indian Journal of Microbiology 12/2014; 54(4). · 0.46 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The recognition of DNA by small molecules is of special importance in the design of new drugs. Many natural and synthetic compounds have the ability to interact with the minor groove of DNA. In the present study, identification of minor groove binding compounds was attained by the combined approach of pharmacophore modelling, virtual screening and molecular dynamics approach. Experimentally reported 32 minor groove binding compounds were used to develop the pharmacophore model. Based on the fitness score, best three pharmacophore hypotheses were selected and used as template for screening the compounds from drug bank database. This pharmacophore-based screening provides many compounds with the same pharmacological properties. All these compounds were subjected to four phases of docking protocols with combined Glide-quantum-polarized ligand docking approach. Molecular dynamics results indicated that selected compounds are more active and showed good interaction in the binding site of DNA. Based on the scoring parameters and energy values, the best compounds were selected, and antibacterial activity of these compounds was identified using in vitro antimicrobial techniques. Copyright © 2014 John Wiley & Sons, Ltd.
    Journal of Molecular Recognition 07/2014; 27(7). · 3.01 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Urinary tract infection is caused primarily by the quorum sensing (QS)-dependent biofilm forming ability of uropathogens. In the present investigation, an anti-quorum sensing (anti-QS) agent curcumin from Curcuma longa (turmeric) was shown to inhibit the biofilm formation of uropathogens, such as Escherichia coli, Pseudomonas aeruginosa PAO1, Proteus mirabilis and Serratia marcescens, possibly by interfering with their QS systems. The antibiofilm potential of curcumin on uropathogens as well as its efficacy in disturbing the mature biofilms was examined under light microscope and confocal laser scanning microscope. The treatment with curcumin was also found to attenuate the QS-dependent factors, such as exopolysaccharide production, alginate production, swimming and swarming motility of uropathogens. Furthermore, it was documented that curcumin enhanced the susceptibility of a marker strain and uropathogens to conventional antibiotics.
    Food Chemistry 04/2014; 148C:453-460. · 3.33 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The LuxS-based signalling pathway has an important role in physiological and pathogenic functions that are capable of causing different infections. In the present study, cinnamaldehyde (CN) and their derivatives were evaluated for their inhibitory efficiency against LuxS by molecular modelling, docking, dynamics and free-energy calculations. Sequence and structure-similarity analysis of LuxS protein, five different amino acids were found to be highly conserved, of which GLY128 was identified as the key residue involved in the effective binding of the ligands. Quantum-polarized ligand docking protocol showed that 2nitro and 4nitro CN has a higher binding efficiency than CN, which very well corroborates with the in vitro studies. COMSTAT analysis for the microscopic images of the S. pyogenes biofilm showed that the ligands have antibiofilm potential. In addition, the results of quantitative polymerase chain reaction (qPCR) analysis revealed that the transcripts treated with the compounds showed decrease in luxS expression, which directly reflects with the reduction in expression of speB. No substantial effect was observed on the virulence regulator (srv) transcript. These results confirm that speB is controlled by the regulation of luxS. The decreased rate of S. pyogenes survival in the presence of these ligands envisaged the fact that the compounds could readily enhance opsonophagocytosis with the reduction of virulence factor secretion. Thus, the overall data supports the use of CN derivatives against quorum sensing-mediated infections caused by S. pyogenes. Copyright © 2014 John Wiley & Sons, Ltd.
    Journal of Molecular Recognition 02/2014; 27(2):106-16. · 3.01 Impact Factor
  • Shanmugaraj Gowrishankar, Balan Poornima, Shunmugiah Karutha Pandian
    [Show abstract] [Hide abstract]
    ABSTRACT: Since Streptococcus mutans is the principal etiologic agent causing dental caries, by encompassing an array of unique virulence traits, emerging treatment strategies that specifically target the virulence of this pathogen may be promising as alternative approaches compared to conventional antibiotic therapy. In this perspective, we investigated chloroform extract of cell-free culture supernatant from mangrove rhizosphere bacterium Bacillus amyloliquefaciens (MMS-50) in terms of anticariogenic properties of S. mutans, without suppressing its viability. Crude chloroform extract of MMS-50 was subjected to column and high performance liquid chromatographic techniques to obtain the active fraction (AF), and MMS-50 AF was used for all further assays. GC–MS and FT-IR were carried out to identify the major components present in MMS-50 AF. Comparative gene expression analysis of some biofilm-forming and virulence genes (vicR, comDE, gtfC, and gbpB) was done by real-time PCR. Cyclo(L-leucyl-L-prolyl) was found to be the chief compound in MMS-50 AF responsible for bioactivity. The minimum and maximum inhibitory concentrations of MMS-50 AF against S. mutans were found to be 100 and 250 μg/mL, respectively. Anti-virulence assays performed using below-sub-MIC levels of MMS-50 AF (30 μg/mL) resulted in significant reduction in adherence (68%), acid production, acid tolerance, glucan synthesis (32%), biofilm formation (53.5%) and cell surface hydrophobicity, all devoid of affecting its viability. The micrographs of CLSM and SEM further confirmed the antibiofilm and anti-virulence efficacies of MMS-50 AF. Expression data showed significant reduction in expression of all studied virulence genes. Thus, the current study unveils the anticariogenic potential of cyclo(L-leucyl-L-prolyl) from B. amyloliquefaciens, as well as its suitability as a novel and alternative anticariogenic agent against dental caries.
    Research in Microbiology 01/2014; · 2.89 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Computational analysis of sequence homology of the chiSRC gene cluster, encoding a chitinase in Streptomyces peucetius, showed that the gene cluster could be a two-component regulon comprising a sensor kinase (chiS) and a response regulator (chiR). To prove that the ChiSRC is an authentic two-component system, the chiS gene was cloned and expressed in E.coli and the purified protein was used for biochemical analysis. In this report, we provide biochemical evidence to show that the sensor kinase encoded by chiS gene indeed is a histidine kinase capable of autophosphorylation and the histidine 144 residue of the ChiS protein is the phosphate acceptor. An insertion mutation at the chiS locus led to overproduction chitinase protein in S. peucetius implying that the chiC gene is negatively regulated by the two-component system.
    Microbiological Research 08/2013; · 1.99 Impact Factor
  • Rajamohmed Beema Shafreen, Shunmugiah Karutha Pandian
    [Show abstract] [Hide abstract]
    ABSTRACT: Streptococcus pyogenes (SP) is the major cause of pharyngitis accompanied by strep throat infections in humans. 3-keto acyl reductase (FabG), an important enzyme involved in the elongation cycle of the fatty acid pathway of S. pyogenes, is essential for synthesis of the cell-membrane, virulence factors and quorum sensing-related mechanisms. Targeting SPFabG may provide an important aid for the development of drugs against S. pyogenes. However, the absence of a crystal structure for FabG of S. pyogenes limits the development of structure-based drug designs. Hence, in the present study, a homology model of FabG was generated using the X-ray crystallographic structure of Aquifex aeolicus (PDB ID: 2PNF). The modeled structure was refined using energy minimization. Furthermore, active sites were predicted, and a large dataset of compounds was screened against SPFabG. The ligands were docked using the LigandFit module that is available from Discovery Studio version 2.5. From this list, 13 best hit ligands were chosen based on the docking score and binding energy. All of the 13 ligands were screened for Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) properties. From this, the two best descriptors, along with one descriptor that lay outside the ADMET plot, were selected for molecular dynamic (MD) simulation. In vitro testing of the ligands using biological assays further substantiated the efficacy of the ligands that were screened based on the in silico methods.
    Journal of molecular graphics & modelling 08/2013; 45C:1-12. · 2.17 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Infectious diseases caused by bacteria and fungi are the major cause of morbidity and mortality across the globe. Multi-drug resistance in these pathogens augments the complexity and severity of the diseases. Various studies have shown the role of biofilms in multi-drug resistance, where the pathogen resides inside a protective coat made of extracellular polymeric substances. Since biofilms directly influence the virulence and pathogenicity of a pathogen, it is optimal to employ a strategy that effectively inhibits the formation of biofilm. Pomegranate is a common food and is also used traditionally to treat various ailments. This study assessed the anti-biofilm activity of a methanolic extract of pomegranate against bacterial and fungal pathogens. Methanolic extract of pomegranate was shown to inhibit the formation of biofilms by Staphylococcus aureus, methicillin resistant S. aureus, Escherichia coli, and Candida albicans. Apart from inhibiting the formation of biofilm, pomegranate extract disrupted pre-formed biofilms and inhibited germ tube formation, a virulence trait, in C. albicans. Characterization of the methanolic extract of pomegranate revealed the presence of ellagic acid (2,3,7,8-tetrahydroxy-chromeno[5,4,3-cde]chromene-5,10-dione) as the major component. Ellagic acid is a bioactive tannin known for its antioxidant, anticancer, and anti-inflammatory properties. Further studies revealed the ability of ellagic acid to inhibit the growth of all species in suspension at higher concentrations (>75 μg ml(-1)) and biofilm formation at lower concentrations (<40 μg ml(-1)) which warrants further investigation of the potential of ellagic acid or peel powders of pomegranate for the treatment of human ailments.
    Biofouling 08/2013; · 3.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Group A Streptococcus (Streptococcus pyogenes) is responsible for a wide array of infections and incidence is high in developing countries like India. Although distribution of emm types of S. pyogenes in India has been described, its association with the virulence genes and ocular isolates is less concentrated. In the present study emm type surveillance as well as its association with toxin gene profile was analyzed. Ocular infected cases such as lacrimal abscess, corneal ulcers, mucocoele showed the presence of 20 S. pyogenes isolates. For noninvasive isolates, we screened 370 pharyngitis cases and 400 asymptomatic school children and recovered 33 pharyngitis and 14 carrier isolates respectively. 14 emm type distributions were observed in ocular isolates, 11 emm types each in pharyngitis and asymptomatic carrier isolates. The two dominant emm types, emm49 and emm63 were accounted for 33% of the total S. pyogenes isolates. Among ocular isolates, slo, smeZ, speB and speG were found in >50% of isolates, in pharyngitis smeZ (48%), speB (45%) and speG (42%) genes were found to be prevalent. Alarmingly, carrier isolates showed more prevalence to virulence genes than the ocular and pharyngitis isolates with speF (79%), speB, speG (64%), slo and sil (64%). Among the three groups, pharyngitis isolates harbored more prtF1 (33%) and prtF2 (94%) than the asymptomatic carriers (28% and 71%) and the ocular isolates (45% and 40%). 450bp size band in prtF1 and 350bp size band in prtF2 showed dominance. Among the three groups tested, the distribution of ermB and mefA was high in pharyngitis isolates (30%) where 10 isolates showed the presence of both genes. None of the isolates showed the presence of ermA and tetO genes. Dendrogram generated based on the virulence and antibiotic resistance gene profiles revealed that except one cluster, all other clusters showed some correlation with ocular, pharyngitis and asymptomatic carrier isolates, irrespective of their emm types.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 07/2013; · 3.22 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Quorum sensing (QS) is a process of cell-cell communication mechanism occurs between the bacterial cells through the secretary signal molecules. This QS mechanism has been shown to control over the expression of various genes responsible for the production of virulence factors in several bacterial pathogens. Hence, the present study was intended to evaluate the antipathogenic potential of mangrove trees of the genus Rhizophora against the QS dependent virulence factors production in Pseudomonas aeruginosa PAO1, clinical isolates CI-I (GU447237) and CI-II (GU447238). The methanol extract of Rhizophora apiculata and R. mucronata (1mg/ml) showed significant inhibition against QS dependent virulence factors production such as LasA protease, LasB elastase, total protease, pyocyanin pigment production and biofilm formation in P. aeruginosa PAO1, CI-I and CI-II. This study for the first time, reports the quorum sensing inhibitory (QSI) potential of Rhizophora spp. against P. aeruginosa infections.
    Phytomedicine: international journal of phytotherapy and phytopharmacology 06/2013; · 2.97 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Quinolone resistance-determining region is known to be the druggability site of the target protein that undergoes frequent mutation and thus renders quinolone resistance. In the present study, ligands were tested for their inhibitory activity against DNA gyrase of Streptococcus pyogenes involved in DNA replication. In silico mutational analysis on modelled gyrase A revealed that GLU85 had the most possible interactions with all the ligands used for the study. The amino acid residue GLU85 had also been predicted with an essential role of maintaining the three-dimensional structure of the protein. When introduced with a mutation (GLU 85 LYS) on this particular residue, it had readily denatured the whole α-helix (from 80 to 90 amino acids). This was confirmed through the molecular dynamics simulation and revealed that this single mutation can cause many functional and structural changes. Furthermore, LYS85 mutation has altered the original secondary structure of the protein, which in turn led to the steric hindrance during the ligand-receptor interaction. The results based on the G-score revealed that ligands have reduced interaction with the mutant protein. The semisynthetic fluoroquinolone 6d, which is an exception, forms a strong interaction with the mutant protein and was experimentally verified using the antimicrobial test. Hence, the present study unravels the fact that mutation at the drug binding site is the major cause for different level of resistance by the S. pyogenes when exposed against the varying concentrations of the fluoroquinolones. Furthermore, a comparative assessment of quinolone derivative with the older generation fluoroquinolones will be of great impact for S. pyogenes-related infections. Copyright © 2013 John Wiley & Sons, Ltd.
    Journal of Molecular Recognition 06/2013; 26(6):276-85. · 3.01 Impact Factor
  • Balu Jancy Kalpana, Shunmugiah Karutha Pandian
    [Show abstract] [Hide abstract]
    ABSTRACT: A halotolerant α-amylase having the ability of digesting the insoluble raw starches was characterized from Bacillus subtilis S8-18, a marine sediment isolate from Palk Bay region. The electrophoresis techniques unveiled that the α-amylase was indeed a monomer with a molecular weight of 57 kDa. The optimum temperature and pH for the enzyme activity were 60 °C and 6.0 respectively. The enzyme was highly stable for 24 h over a wide range of pH from 4.0 to 12.0 by showing 84-94% activity. Interestingly, by retaining 72% activity even after 24 h, the enzyme also showed tolerance towards 28% NaCl. The α-amylase retained a minimum of 93% residual activity in 1 mM concentration for the selected divalent metal ions. The enzyme was found to be chelator resistant as it remained unaffected by 1 mM of EDTA and exhibited 96% activity even at 5 mM concentration. Furthermore, though 1% SDS caused remarkable reduction (68%) in amylase activity, the enzyme showed tolerance towards other detergents (1% of Triton-X and Tween 80) with 85% activity. Additionally, the α-amylase enzyme is capable of hydrolyzing the insoluble raw starch substrates which was evident from the scanning electron microscopic (SEM) and spectrophotometric analyses.
    Journal of Basic Microbiology 05/2013; · 1.20 Impact Factor
  • Balu Jancy Kalpana, Muthukrishnan Sindhulakshmi, Shunmugiah Karutha Pandian
    [Show abstract] [Hide abstract]
    ABSTRACT: The present study is aimed at developing an economical medium for the production of α-amylase from Bacillus subtilis S8-18, a marine sediment isolate from Palk Bay, with various agricultural by-products which are cheap and rich in starch. These products included wheat bran, wheat husk, rice bran, rice husk and potato peel and used to replace soluble starch present in the LB broth (synthetic medium). The rice husk was found to be the best to influence enzyme production significantly (61186 IU mL(-1) ) when compared to the yield of 30026 IU mL(-1) obtained by commercial starch. Hence, LB broth containing rice husk was termed as economical medium. Besides, the effect of various nutritional and physiological factors on enzyme production was also investigated. Furthermore, the desizing efficiency of α-amylases produced by synthetic and economical medium was evaluated through various assays like reducing sugar estimation, weight loss assay, drop absorbency assay, SEM and FTIR analyses. In addition, a commercial α-amylase from B. subtilis was also used in desizing analyses for comparative purpose. It revealed that the α-amylase from economical medium was highly effective in desizing the cotton fabrics as that of the commercial enzyme and much superior to the enzyme produced through synthetic medium. This article is protected by copyright. All rights reserved.
    Biotechnology and Applied Biochemistry 05/2013; · 1.35 Impact Factor
  • Kannan Balaji, Ramalingam Thenmozhi, Shunmugiah Karutha Pandian
    [Show abstract] [Hide abstract]
    ABSTRACT: Background & objectives: Subinhibitory concentrations (sub-MICs) of antibiotics, although not able to kill bacteria, but influence bacterial virulence significantly. Fluoroquinolones (FQs) which are used against other bacterial pathogens creates resistance in non-targeted Streptococcus pyogenes. This study was undertaken to characterize the effect of sub-MICs of FQs on S. pyogenes biofilm formation. Methods: Biofilm forming six M serotypes M56, st38, M89, M65, M100 and M74 of S. pyogenes clinical isolates were challenged against four FQs namely, ciprofloxacin, ofloxacin, levofloxacin and norfloxacin. The antibiofilm potential of these FQs was analysed at their subinhibitory concentrations (1/2 to 1/64 MIC) using biofilm assay, XTT reduction assay, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Results: Among the four FQs tested, ofloxacin and levofloxacin at 1/2 MIC showed the maximum inhibition (92%) of biofilm formation against M56 and M74 serotypes. FQs effectively interfered in the microcolony formation of S. pyogenes isolates at 1/2 to 1/8 sub-MICs. Inhibition of biofilm formation was greatly reduced beyond 1/16 MICs and allowed biofilm formation. XTT reduction assay revealed the increase in metabolic activity of S. pyogenes biofilm against the decrease in FQs concentration. SEM and CLSM validated the potential of sub-MICs of FQs against the six S. pyogenes. Interpretation & conclusions: Our results showed that the inhibitory effect all four FQs on S. pyogenes biofilm formation was concentration dependent. FQs at proper dosage can be effective against S. pyogenes and lower concentrations may allow the bacteria to form barriers against the antibiotic in the form of biofilm.
    The Indian Journal of Medical Research 05/2013; 137(5):963-71. · 2.06 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The increasing occurrence of disease outbreaks caused by Vibrio spp. and the emergence of antibiotic resistance has led to a growing interest in finding alternative strategies to prevent vibriosis. Since the pathogenicity of vibrios is controlled in part by quorum-sensing (QS) system, interfering with this mechanism would prevent the pathogenicity of vibrios without developing resistance. Hence, a non-toxic phytochemical curcumin from Curcuma longa was assessed for its potential in reducing the production of QS-dependent virulence factors in Vibrio spp. The obtained results evidenced 88 % reduction in bioluminescence of Vibrio harveyi by curcumin. Further, curcumin exhibited a significant inhibition in alginate, exopolysaccharides, motility, biofilm development and other virulence factors production in Vibrio parahaemolyticus, Vibrio vulnificus and V. harveyi. In in vivo analysis, curcumin enhanced the survival rate of Artemia nauplii up to 67 % against V. harveyi infection by attenuating its QS-mediated virulence.
    Applied Microbiology and Biotechnology 01/2013; · 3.69 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Beyond Staphylococcus aureus being an etiological agent for several serious clinical complications, the foot prints of S. aureus in pharyngitis infection has also been recently recognized. With due response to the fact, a prospective study was conducted between 2009 and 2010 to describe the molecular epidemiology of S. aureus in throat swabs of pharyngitis patients. A total of 63 methicillin-resistant S. aureus (MRSA) and 102 methicillin-susceptible S. aureus (MSSA) isolates were recovered from 265 throat swabs, representing a community-acquired outpatient population from Tamil Nadu, India. Molecular characterization of MRSA was done by two conventional multiplex-PCR assays including Panton-Valentine leukocidin (PVL), mecA and nuc genes, and staphylococcal cassette chromosome mec (SCCmec) typing. Among 165 S. aureus isolates, methicillin resistance was observed in 38.2% (n=63), in which 69.8% (n=44/63) of the MRSA along with 34.5% (n=55/102) of MSSA harbored PVL toxin genes. SCCmec typing showed 50.8% of isolates as SCCmecV (n=32), 44.4% as SCCmecIII (n=28), and 1.6% as SCCmec types I, II and IVa (n=1). Multilocus sequence typing performed for 26 selected MRSA isolates resulted in 12 different sequence types (ST), including a novel ST2129/ SCCmecIII, PVL-positive. Ten MRSA isolates were categorized as ST772 (38.5%)/ SCCmecV, PVL-positive, and 3 isolates as ST368 (11.5%)/ SCCmecIII, PVL-negative. Though the prominent clones of ST772/ SCCmecV were multidrug-susceptible worldwide, they were highly multidrug-resistant in the current study, including 4 clones intermediate to vancomycin. Totally, 10 (15.9%) out of 63 MRSA isolates were documented as vancomycin-intermediate S. aureus (VISA). Collectively, the present study for the first time portrayed the high prevalence of active MRSA pharyngitis infection and also emphasizes an alarming need for discrimination of pharyngeal-asymptomatic carriers of S. aureus from those with an active S. aureus pharyngitis infection.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 01/2013; · 3.22 Impact Factor
  • Kannan Balaji, Peter Awili Okonjo, Ramalingam Thenmozhi, Shunmugiah Karutha Pandian
    [Show abstract] [Hide abstract]
    ABSTRACT: A total of 31 Vibrio cholerae O1 (4- Inaba and 27- Ogawa serotype) isolates collected during a three-year period (2006-2009) from acute diarrheal cases in Tamil Nadu, India were analyzed for antibiotic resistance profiling, virulence-associated factors, genetic profiling by enterobacterial repetitive intergenic consensus sequence polymerase chain reaction (ERIC PCR), and biofilm-forming ability. Antibiotic resistance profile revealed that most of the strains have become multidrug-resistant strains. All the isolates are resistant to ampicillin and polymyxin B, 97% of the isolates are resistant to nalidixic acid, 90% to co-trimoxazole, 32.3% to norfloxacin and ciprofloxacin, 29% to doxycycline, 10% to gentamicin, whereas only 3% to chloramphenicol. Molecular characterization of virulence-associated genes by multiplex PCR revealed the presence of ace, ctxA, tcpA, toxR, and ompU as 93.5%, followed by ompW with 33.3%. The presence of zot was restricted to only one isolate and hlyA was not encountered in any of the strains. ERIC PCR produced more than 10 bands for each isolate and the dendrogram generated based on the cluster analysis showed the presence of 29 electrophoretic types among the 31 isolates. Isolates from different area or year of isolation are intermingled in all the clusters. With respect to biofilm formation, 24 isolates were found to be biofilm formers and eight of them produced strong biofilm. This study demonstrates the presence of critical virulence factors and antibiotic resistance in the diarrhea isolates, which signifies the importance of routine monitoring and proper treatment to prevent cholera outbreaks.
    Microbial drug resistance (Larchmont, N.Y.) 01/2013; · 1.99 Impact Factor
  • Dhamodharan Bakkiyaraj, Chandran Sivasankar, Shunmugiah Karutha Pandian
    [Show abstract] [Hide abstract]
    ABSTRACT: Infections of Pseudomonas aeruginosa are of great concern because of its increasing resistance towards conventional antibiotics. Quorum sensing system of P. aeruginosa acts as a global regulator of almost all the virulence factors and majorly its biofilm formation. In the present study, quenching of QS system of P. aeruginosa has been explained with bioactives from bacteria associated with the coral Acropora digitifera. Isolated bioactives inhibited the expression of various virulence traits of P. aeruginosa like biofilm formation, and the production of extracellular enzymes like protease and elastase. This study also emphasises the potential of coral associated bacteria in producing bioactive agents with anti-pathogenic properties.
    Indian Journal of Microbiology 01/2013; 53(1):111-113. · 0.46 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacterial community composition in the marine environment differs from one geographical location to another. Reports that delineate the bacterial diversity of different marine samples from geographically similar location are limited. The present study aims to understand whether the bacterial community compositions from different marine samples harbour similar bacterial diversity since these are geographically related to each other. In the present study, 16S rRNA deep sequencing analysis targeting V3 region was performed using Illumina bar coded sequencing. A total of 22.44 million paired end reads were obtained from the metagenomic DNA of Marine sediment, Rhizosphere sediment, Seawater and the epibacterial DNA of Seaweed and Seagrass. Diversity index analysis revealed that Marine sediment has the highest bacterial diversity and the least bacterial diversity was observed in Rhizosphere sediment. Proteobacteria, Actinobacteria and Bacteroidetes were the dominant taxa present in all the marine samples. Nearly 62-71% of rare species were identified in all the samples and most of these rare species were unique to a particular sample. Further taxonomic assignment at the phylum and genus level revealed that the bacterial community compositions differ among the samples. This is the first report that supports the fact that, bacterial community composition is specific for specific samples irrespective of its similar geographical location. Existence of specific bacterial community for each sample may drive overall difference in bacterial structural composition of each sample. Further studies like whole metagenomic sequencing will throw more insights to the key stone players and its interconnecting metabolic pathways. In addition, this is one of the very few reports that depicts the unexplored bacterial diversity of marine samples (Marine sediment, Rhizosphere sediment, Seawater) and the host associated marine samples (Seaweed and Seagrass) at higher depths from uncharacterised coastal region of Palk Bay, India using next generation sequencing technology.
    PLoS ONE 01/2013; 8(10):e76724. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Dendrophthoe falcata is a hemiparasitic plant commonly used for ailments such as ulcers, asthma, impotence, paralysis, skin diseases, menstrual troubles, pulmonary tuberculosis, and wounds. In this context, the validations of the traditional claim that the leaf extract of D. falcata possesses antibiofilm and anti-quorum sensing activity against different bacterial pathogens were assessed. The bacterial biofilms were quantified by crystal violet staining. Among the 17 bacterial pathogens screened, the methanolic fraction of the leaf extract clearly demonstrated antibiofilm activity for Proteus mirabilis, Vibrio vulnificus, Aeromonas hydrophila, Shigella sonnei, Chromobacterium violaceum ATCC 12472, Vibrio parahaemolyticus, Vibrio harveyi, Vibrio alginolyticus, Vibrio cholerae, and Proteus vulgaris. At biofilm inhibitory concentrations, biofilm formation was reduced by up to 70-90 %. Furthermore, the potential quorum-sensing activity of the leaf extract was tested by agar well diffusion using Chromobacterium violaceum (ATCC 12472 & CV O26) reporter strains. The inhibition of violacein production may be due to direct or indirect interference on QS by active constituents or the interactive effect of different phytocompounds present in the extracts. This is the first report on antibiofilm and QS activity of D. falcata leaf extracts, signifying the scope for development of complementary medicine for biofilm-associated infections.
    Planta Medica 10/2012; · 2.35 Impact Factor