Bioremediation of Crude Oil Using Bacterium from the Coastal Sediments of Kish Island, Iran

BACKGROUND Much of the environment is affected by petroleum contamination. It imposes serious health problems for humans as well as serious environmental impact. Bioremediation is an important consideration for removing environmental pollutants because, compared with other technologies, it incurrs lower costs and is environmentally compatible. METHODS Crude oil degrading bacteria were isolated using serial dilutions of a bacterial consortium. The Taguchi experimental design L16 (4(5)) was used to optimize the biodegradation process of crude oil by the isolated strain. This investigation applied the parameters of temperature, salinity, pH, NH4Cl and FeSO4.7H2O. Modeling the kinetics of crude oil biodegradation included five batch cultivation experiments (2.5 ml/L to 40 ml/L) using crude oil as a single limiting substrate. RESULTS Halomonas sp. MS1 was identified using identification tests. Maximum biodegradation efficiency was predicted to occur at pH=9, temperature=30 °C, salinity=2%, NH4Cl concentration=0.4 g/L and FeSO4.7H2O=0.04 g/L. After optimization, biodagradation was significantly (P<0.05) higher (i.e. 90.65%) than it results under the original conditions. Furthermore, growth kinetics modelling of bacteria in various concentrations of crude oil showed a positive correlation between increased concentration, up to 10 ml/L and bacterial growth, but this was not evident at higher concentrations (20-40 mL/L). CONCLUSION Overall, bacteria in surface sediment samples from Kish Island have been determined as having good potential for application in oil biodegradation. Optimum amounts of the studied factors were determined successfully by applying the Taguchi experimental design and the models of Teissier and Haldane are suggested as kinetic models to describe the batch crude oil degradation behavior of MS1.