Degradation of Phenol by Selected Strains of Bacillus Species Isolated from Marine Water

Several external factors can limit the rate of biodegradation of organic compounds. These factors may include temperature, pH, oxygen content and availability, substrate concentration and physical properties of contaminants. Each of these factors should be optimized for the selected organism for the maximum degradation of the organic compound of choice. The optimization of the substrate concentration in phenol biodegradation is particularly important since it inhibits the growth of the organism at higher concentrations. Thus the present study was planned to provide scientific justification for the biodegradation of phenol by Bacillus sp., which were isolated from marine water. Marine water samples were collected and processed for the isolation and identification of phenol degrading bacterium. Based on the morphological, physiological and biochemical characteristics the isolates were identified as two different species of Bacillus. Basal minimal medium was prepared and inoculated with these two different species of Bacillus for the study of biodegradation of phenol. Biomass study was carried out to measure the cell growth of Bacillus sp., against phenol. At different time intervals of 24 hrs, 48 hrs, 72 hrs, 96 hrs and 120 hrs the turbidity of the culture was measured and observed for biomass study at 600 nm. After 120 hrs the highest biomass was observed in both strains which were indicated by increased cell growth. Cell free supernatant was collected and degradation of phenol was measured by rapid colorimetric method using 4-amino antipyrine. Optimization of various parameters was carried out to analyse the effect of various temperatures, pH, Nacl concentrations, urea concentrations, phenol concentrations, glucose concentrations on phenol degradation. After the appropriate time period of degradation, the concentration of phenol in the culture medium was measured by the technique of Thin Layer Chromatography using the Rf values of samples compared with Rf values of standard phenol solution. Rf values were found to be 0.8 and 1.0 for SI and SII isolates. Therefore, the result revealed that the Bacillus strains isolated from marine water have the ability to degrade phenol which is one of the hazardous pollutants of environment and these strains could be used as an effective biodegrading agents of phenol which degrade phenol in to non-toxic by-products.