Assessment of biodegradation efficiency of some isolated bacteria from oil- contaminated sites in solid and liquid media containing oil-compounds

Oil contamination in Iran due to high application of oil compounds, is one of the most dangerous pollution factors. Bioremediation is one of principal strategies for remediation, where in the pollutants can be removed by use of microorganism or any biological process that uses microorganisms or their enzymes to return the environment altered by contaminants to its original condition. With regards to the importance of bioremediation, hydrocarbon degrading efficiency of some isolated bacteria from oilpolluted sites of Bushehr province, such as Pseudomonas stutzeri, Pseudomonas alcaligenes, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Serattia odorifera, Achromobacter xylosoxidans, Acinetobacter johnsonii, Entrobacter cloacae, Ralstonia sp., Vibrio sp., Sphingobacterium sp., Zymomonas sp., Paracoccus sp., Pantoea sp. and Chryseobacterium sp. were determined in a solid and liquid medium enriched by gas oil (2%), toluene (1%) and phenanthrene (0.05%). In order to determine the efficiency of these bacteria in hydrocarbon-degrading an inoculum of bacteria containing 10 cfu/ml was used in plate and liquid assays, which were performed in factorial experiment based on completely randomized design with 3 replications. The increasing of diameter of colony and the growth turbidity (OD600nm) as indicators for utilization of hydrocarbon was measured in solid and liquid assays, respectively. Results showed that in CFMM plate assay, highest diameter of colony in presence of toluene and phenanthrene were achieved by Chryseobacterium sp. and Sphingobacterium sp., while in liquid assay and in presence of three compounds Serattia odorifera and Entrobacter cloacae were efficient. Moreover, among three compounds highest degradability in bioremediation was related to gas oil, and it’s followed by phenanthrene and toluene, respectively.