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ABSTRACT: A total of 161 different Streptomyces isolates were recovered from 5 soil samples representing the driest habitats of Jordan. These were then characterized and
assessed for their antagonistic activity against four clinical multi-drug resistant Pseudomonas
aeruginosa test pathogens. Results indicated that only 3 strains out of 139 and 6 out of 22 isolated at 27°C and 45°C, respectively,
were active against at least three strains of pathogenic Pseudomonas. However, three Streptomyces strains (J2b, J4, and J12) that were isolated at 45°C inhibited all of the tested pathogens with an inhibition zone ranging between 5 and 16mm in
diameter. Data obtained from comparing the inhibition activity of these unique Streptomyces strains toward multi-resistant Pseudomonas pathogens with standard used antibiotics revealed that these isolates produce possible different inhibitory bioactive compounds
other than the standard antibiotics.
World Journal of Microbiology and Biotechnology 04/2012; 24(2):157-162. · 1.53 Impact Factor
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ABSTRACT: The investigation aimed to examine the Streptomyces flora of hydrocarbon-contaminated soil and study their capability to grow on diesel fuel as a sole carbon source and their
analysis for the presence of the alkane hydroxylase gene (alkB) by PCR. A total of 16 Streptomyces isolates were recovered from hydrocarbon-contaminated soil samples on starch casein nitrate agar medium with the ability
of 3 isolates to grow on diesel as evaluated by agar plate diffusion method, enzymatic assay and dry weight measurements.
PCR analysis of the isolates for the presence of the alkB gene showed two groups with different band size products; group 1 (G1) (316–334bp) and group 2 (G2) (460–550bp). Three
isolates (SF.1Ac, SF.2Ba, and SF.3Ad) grew around diesel-containing wells and contained the alkB gene with size band ranged between 320 and 550bp. However; one isolate (SF.1Aa) did not show any PCR product although it
was able to grow on diesel. This implies that the alkB gene is not the only gene that is responsible for the degradation of alkanes. Further, the variation in the G2 fragment size
probably indicates different related genes that might be involved in alkane degradation rather than a single gene.
World Journal of Microbiology and Biotechnology 04/2012; 24(10):2191-2198. · 1.53 Impact Factor
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ABSTRACT: Cronobacter spp. (formerly Enterobacter sakazakii), are a group of Gram-negative pathogens that have been implicated as causative agents of meningitis and necrotizing enterocolitis in infants. The pathogens are linked to infant formula; however, they have also been isolated from a wide range of foods and environmental samples.
In this study, 233 samples of food, infant formula and environment were screened for the presence of Cronobacter spp. in an attempt to find its source. Twenty nine strains were isolated from samples of spices, herbs, infant foods, and dust obtained from household vacuum cleaners. Among the 76 samples of infant food, infant formula, milk powder and non-milk dairy products tested, only one sample of infant food contained Cronobacter spp. (1.4%). The other Cronobacter spp. isolates recovered include two from household vacuum dust, and 26 from 67 samples of herbs and spices. Among the food categories analyzed, herbs and spices harbored the highest number of isolates, indicating plants as a possible reservoir of this pathogen. Initial screening with API 20E test strips yielded 42 presumptive isolates. Further characterization using 3 chromogenic media (alpha-MUG, DFI and EsPM) and 8 sets of PCR primers detecting ITS (internal transcribed spacer sequences), 16S rRNA, zpx, gluA, gluB, OmpA genes followed by nucleotide sequencing of some PCR amplicons did not confirm the identity of all the isolates as none of the methods proved to be free of both false positives or false negatives. The final confirmation step was done by 16S rRNA sequence analysis identifying only 29 of the 42 isolates as Cronobacter spp.
Our studies showed that Cronobacter spp. are highly diverse and share many phenotypic traits with other Enterobacteriaceae members highlighting the need to use several methods to confirm the identity of this pathogen. None of the biochemical, chromogenic or PCR primers proved to be a reliable method for confirmation of the identity of the isolates as all of them gave either false positives or false negatives or both. It is therefore concluded that 16S rRNA sequencing is pivotal to confirm the identity of the isolates.
BMC Microbiology 10/2009; 9:225. · 3.04 Impact Factor
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ABSTRACT: The purpose of this study was to determine the influence of growth conditions and medium composition on the production ofchitinase by Streptomyces sp. (strain S242). Production of chitinase by strain S242 was detected on colloidal chitin agar (CCA) medium after 8 days of incubation at 28 degrees C resulting in a clear zone 10 mm around the colony. Chitinase activity was assayed as the amount of N-acetylglucosamine released in micromol/ml/min using the dinitrosalicylic acid assay method. The crude enzyme had maximum activity (0.162 U ml/l) after 4 days of incubation at pH 7 and 30 degrees C when the broth medium was supplemented with 1.6% of colloidal chitin. However, enzyme activity was strongly decreased at 40 degrees C and extreme acidic and alkaline pH values. SDS-PAGE and zymogram analysis revealed six distinctive bands that range from 39 to 97 kDa with chitinolytic activity. The findings of this investigation create a possibility for the use of the organism in the commercial production of chitinase. In addition, it can be a source of DNA for cloning the chitinase gene(s) to generate phytopathogen resistant transgenic plants.
Polish journal of microbiology / Polskie Towarzystwo Mikrobiologów = The Polish Society of Microbiologists 01/2009; 58(4):339-45. · 0.76 Impact Factor
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ABSTRACT: A total of 231 different soil Streptomyces isolates were recovered from 16 different locations in North Jordan. They were assessed for their phytotoxic activity on seeds of cucumber (Cucumis sativus L.) and ryegrass (Lolium perenne L.) placed adjacent to a 2 cm wide Streptomyces culture strips grown at 28C degrees for 3 weeks on starch casein nitrate (SCN) agar. Phytotoxicity was ascertained on the basis of suppressed seed germination, discoloration of the root tip, reduced root and the shoot growth and eventual death of the root. Twenty one of the isolates exhibited adverse effect against growth of germinated cucumber seeds, germination and growth of ryegrass seeds. Using filter paper bioassay method, culture filtrate from the SCN broth of the isolate R9; identified as Streptomyces aburaviensis, significantly inhibited seed germination, radicle and shoot growth ofryegrass, reduced radicle and shoot growth of cucumber and suppressed the shoot growth of milk thistle (Silybum marianum L.). Also, culture filtrate from the glucose-peptone-molasses (GPM) broth diluted (1:1) with sterilized distilled water caused complete inhibition of seed germination of redroot pigweed (Amaranthus retroflexus L.). Dichloromethane extracted fraction of S. aburaviensis (strain R9) culture filtrate from GPM broth completely inhibited seed germination of ryegrass when applied at doses of 3 and 5 mg of dry weight, and the seedling growth of cucumber and milk thistle was severely reduced by the same doses.
Polish journal of microbiology / Polskie Towarzystwo Mikrobiologów = The Polish Society of Microbiologists 02/2008; 57(4):297-305. · 0.76 Impact Factor
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ABSTRACT: The purpose of this study was to determine the influence of growth conditions and medium composition on the cellulase enzyme production by Streptomyces sp. Production of cellulase enzyme by a Streptomyces strain (J2) was detected on cellulose agar (CA) medium after 4 days of incubation at 28 °C that exhibited a clear zone of 22 mm around the colony. Cellulase production was assayed by measuring the amount of glucose liberated in μmol/ml/min by using the dinitrosalicylic acid assay method. The highest crude enzyme activity (432 U/l) was observed after 3 days of incubation at pH 7 and 60 °C in a medium that was supplemented with 0.5% glucose, 0.2% starch, and 0.2% NH4CL. However, enzyme production and activity were strongly decreased at 45°C and acidic pH. Enzyme production and activity were also inhibited when Streptomyces strain (J2) was grown in CMC broth supplemented with arabinose and yeast extract as a sole carbon and nitrogen source, respectively. ﻂﺳﻮﻟا ﺐﻴآﺮﺗو ﻮﻤﻨﻟا فوﺮﻇ ﺮﻴﺛﺄﺗ ﺔﺳارد ﺚﺤﺒﻟا اﺬه ﻦﻣ فﺪﻬﻟا نﺎآ ـﻟا ﺎﻳﺮﻴﺘﻜﺑ ﻦﻣ ﺰﻴﻠﻴﻠﺴﻟا ﻢﻳﺰﻧإ جﺎﺘﻧإ ﻰﻠﻋ ﻲﺋاﺬﻐﻟا Streptomyces . ﻢﺗ
