Monday, July 27, 2009
P92
Isolation of a strain of Alcaligenes faecalis with wide range antimicrobial activity from oil-polluted soil
New antimicrobial agents have needed due to emergence of antibiotic resistant microorganisms. Here, we describe a new bacterial strain, capable of producing an extra cellular antimicrobial agent. It was originally isolated from oil-polluted soil samples from Dezful, Iran. 16srRNA sequencing revealed close relationship to Alcaligenes faecalis with 99% similarity. Furthermore, Microbiological, biochemical and morphological examinations characterized this strain as gram negative, aerobic, coccobacillus, motile, oxidase and catalase positive. This strain was able to assimilate benzoate, l-histidine, and l-tryptophane and was able to produce alkaline from organic salt as sole carbone source. Antimicrobial agent was heat stable (up to 100 °C for 1h) and is susceptible to low pH (<7) but stable in neutral and alkaline pH. The polar nature was determined by lack of extraction by chloroform, ethanol, or ethyl acetate. The antimicrobial agent produced by isolated bacterium caused reductions in counts of bacteria (Pseudomonas aeruginosa ATCC 85327, Escherichia coli ATCC 25922, Serratia marcescens, Klebsiella pneumoniae ATCC 10031, Staphylococcus aureus ATCC 25923, and Bacillus subtilis ATCC 465), yeast (Candida albicans ATCC 10231), and filamentous fungus (Aspergillus niger). Isolated bacterium produced antimicrobial agent in both complex media (nutrient broth, Mueller-hinton broth and trypticas soya broth and synthetic media (acetate or citrate as sole carbone source with defined media) and determined acetate broth was best medium for growth of this strain and production antimicrobial agent. The optimal pH and temperature range for growth and production antimicrobial agent was determined as 8-9 and 35-40 °C, respectively.
Keywords: Antimicrobial agent, Alcaligenes, oil-polluted soil
Keywords: Antimicrobial agent, Alcaligenes, oil-polluted soil
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