Phenol degradation performance by isolated Bacillus cereus immobilized in alginate

Phenol degradation by Bacillus cereus AKG1 MTCC9817 and AKG2 MTCC 9818 was investigated and degradation kinetics are reported for the free and Ca-alginate gel-immobilized systems. The optimal pH for maximum phenol degradation by immobilized AKG1 and AKG2 was found to be 6.7 and 6.9, respectively, while 3% alginate was optimum for both the strains. The degradation of phenol by free as well as immobilized cells was comparable at lower concentrations of phenol (100-1000 mg l(-1)). However, the degradation efficiency of the immobilized strains was higher than that of the free strains at higher phenol concentrations (1500-2000 mg l(-1)), indicating the improved tolerance of the immobilized cells toward phenol toxicity. More than 50% of 2000 mg l(-1) phenol was degraded by immobilized AKG1 and AKG2 within 26 and 36 days, respectively. Degradation kinetics of phenol by free and immobilized cells are well represented by the Haldane and Yano model. (C) 2011 Elsevier Ltd. All rights reserved.