Assessment of the BTEX biodegradation by Bacillus thuringiensis and Bacillus sp. under nitrate reducing condition.

Lack of oxygen and high salinity are factors that limit the biodegradation of the hydrocarbon. The electron accepters such as nitrate and salt tolerant bacteria can be used to increase the biodegradation rate in saline environment with low level of oxygen. In this paper, BTEX biodegradation by Bacillus thuringiensis andBacillus sp. is investigated in microaerophilic and saline environment under nitrate reducing condition. Firstly, the ability of the above- mentioned bacteria in BTEX biodegradation was confirmed. Then, the effect of Nitrate, BTEX concentration, salinity and cell mass on BTEX degradation was studied using Taguchi method and design expert software. The results of this study showed the ability of the Bacillus thuringiensis andBacillus sp. on BTEX degradation. For 200 mg/L BTEX concentration, the high efficiency of degradation by Bacillus thuringiensis andBacillus sp. could be achieved in optimum conditions; Nitrate Concentration (200 mg/L), salinity (1 and 5 %) and cell mass (1and 5×107 cell/ml) respectively.