Phenol degradation by Bacillus cereus: Pathway and kinetic modeling

The microbial degradation of phenol by pure cultures Bacillus cereus MTCC 9817 strain AKG1 and B. cereus MTCC 9818 strain AKG2 is studied in batch mode for several initial concentrations of phenol in the range of 100–2000 mg/L with an interval of 100 mg/L. Degradation pathways are investigated at initial phenol concentrations of 100, 500, 1000, 1500, and 2000 mg/L. The bacteria are able to degrade phenol of concentration as high as 2000 mg/L. The maximum degradation rate is obtained at an initial phenol concentration of about 800 mg/L for the strain AKG1 and about 200 mg/L for the strain AKG2. Both the strains degrade phenol via meta-cleavage pathway through formation of 2-hydroxymuconic semialdehyde (2-HMSA) as an intermediate product. Modeling of the biodegradation of phenol indicates that the Haldane inhibitory model predicts the experimental data fairly well for both the strains.