ACCELERATED BIODEGRADATION OF HIGH AND LOW CONCENTRATIONS OF P-NITROPHENOL (PNP) BY BACTERIAL INOCULATION IN INDUSTRIAL WASTE-WATER - THE ROLE OF INOCULUM SIZE ON ACCLIMATION PERIOD

The effect of inoculum size on the acclimation period and rate and ext ent of p-nitrophenol (PNP) degradation at high (1-10 mg/L) and low (26 mu g/L) concentrations for two bacteria was determined in defined med ia as well as industrial wastewater. Increased inoculum size did not a ffect the acclimation period of either bacterium at high (1-10 mg/L) P NP concentrations. At low PNP concentrations (26 mu g/L), the two bact eria behaved differently. The acclimation period was shortened and bot h the rate and extent of mineralization of PNP were enhanced by increa sing the Corynebacterium sp. inoculum size from 3 X 10(5) to 3 X 10(6) cells/ml. Addition of phosphate or elimination of predators also redu ced the acclimation period. Conversely, increasing the inoculum size f rom 3 X 10(5) to 5 X 10(6) cells/ml of Pseudomonas putida lengthened t he acclimation period and reduced both the rate and extent of minerali zation. It is suggested that, in a given environment, the success of a n introduced species to enhance the degradation of a chemical depends upon (i) concentration of the chemical, (ii) selection of an appropria te microorganism and (iii) utilization of a suitable inoculum size.