Isolation and characterization of phenol degrading bacteria from soil contaminated with paper mill wastewater

Abstract

Biological treatment with pure bacterial strain is an efficient method for phenolic wastewater treatment. In the present study, pure culture of a Gram-negative bacterium (strain PS3) was isolated from the soil sample of paper mill wastewater discharge site. Strain PS3 was identified on the basis of morphological, biochemical characteristics and 16S rDNA sequence, and found to be as <em>Burkholderia </em>sp. The effect of initial phenol concentration (500 to 1500 mg/L) on microbial growth and biodegradation rate was studied in batch experiments. The 98.86, 98.62, 83.3, 51.2 and 17.3% degradation of 500, 750, 1000, 1250 and 1500 mg/L concentrations of phenol was achieved, respectively. It was found that by increasing the concentration of phenol, the lag phase prolonged due to inhibitory nature of phenol. Haldane model fitted to the growth kinetics data well for the entire phenol concentration range (0-1500 mg/L) and the kinetic parameters, maximum specific growth rate (&micro;_max), half-saturation coefficient (K_s) and the substrate inhibition constant (K_i) were estimated as 0.0436 h^-1, 29.43 mg/L and 839.90 mg/L, respectively. These results show that the <em>Burkholderia </em>sp. PS3 follows substrate inhibition kinetics.