Influence of ph and inoculum size on phenol utilization by bacterial strains isolated from oil refinery effluent

Abstract

The influence of pH and inoculum size on phenol utilization by bacterial isolates from oil refinery effluent was investigated. The substrate used for the assessment was phenol, which formed a model substrate for the experiment. Phenol was progressively degraded at pH range of 6.3 to 8.0. Maximum phenol degradation by Bacillus sp. RBD1 and Corynebacterium sp. RBD2 was obtained at pH value of 7.1. Conversely, utilization of phenol at pH 5.5 was significantly high for both organisms. Phenol was degraded at every cell density (inoculum size) tested with the two organisms but phenol degradation rate increased with increasing inoculum size. Cultures of Bacillus sp. RBD1 and Corynebacterium sp.RBD2 with the lowest cell densities exhibited highest specific rate of utilization of phenol. The results obtained indicated lower phenol utilization rate per colony forming unit at higher cell density. It was also found that pH 6.3 to 8.0 was found to be optimal for phenol degradation by the test organisms.

Keywords: Phenol, pH, refinery wastewater, bacteria, inoculum size, biodegradation

International Journal of Natural and Applied Sciences, 7(1): 8 - 15, 2011 ISSN: 0794 – 4713