Isolation and characterization of hyper phenol tolerant Bacillus sp. from oil refinery and exploration sites

Bacillus cereus MTCC 9817 strain AKG1 and B. cereus MTCC 9818 strain AKG2 were isolated from petroleum refinery and oil exploration site, respectively. The 16S rDNA sequence of strain AKG1 showed the closest relation to B. cereus 99.63% and Bacillus coagulans 99.63% followed by 99.34% homology with Bacillus thuringiensis strain 2PR56-10. AKG2 is mostly related to B. thuringiensis strain CMG 861 with 99.37% homology. The similarity search between AKG1 and AKG2 gave the lowest similarity 99.19% among same genus similar sequences. At phenol concentration of 1000 mg/L, the optimum growth conditions for AKG1 were found to be 37 degrees C and pH 7.0 and the same were found to be 37 degrees C and pH 7.5 for AKG2. The growth kinetics of the strains AKG1 and AKG2 are best fitted by Yano model (maximum growth rate, mu(max)=1.024 h(-1) and inhibition constant, K(I)=171,800 mg/L) and Edward model (mu(max)=0.5969 h(-1) and K(I)=1483 mg/L) respectively. Growth kinetics of both the strains are also well fitted by the Haldane model with mu(max)=0.4396 h(-1) and K(I)=637.8 mg/L for AKG1 and mu(max)=0.9332 h(-1) and K(I)=494.4 mg/L for AKG2.