Effect of various growth Conditions on Phenol Degradation by two Bacillus cereus Strains

Phenol is a toxic environmental pollutant. Two strains of Bacillus cereus (RC29 and RM4) capable of utilizing phenol as their carbon source were selected to study the effects of various growth parameters such as pH, temperature, volume of inoculum, period of incubation, and the concentration of substrate (phenol) on its phenol degradation abilities and thereby optimizing the growth conditions for their maximum phenol degradation. The minimal salt phenol medium (MSPM) was used. Both the strains gave maximum phenol degradation under ideal growth conditions of pH 7, temperature 370C, 5% (v/v) inoculum volume, and an incubation period of three days. At high substrate concentration, the growth and degradation were found to be decreasing gradually. For strain RM4, the highest degradation was perceived at 40 mM phenol concentration (39.47%). For RC29, it was observed to be 60mM concentration (39.22%). It was also observed that there is a strong relationship between the volume of inoculum and the rate of phenol degradation. The enhanced phenol-degrading ability of these strains under the optimized conditions can be suggested as a promising tool for the treatment of phenol-contaminated wastewater or effluents.