APPLICATION OF THE POLYMERASE CHAIN-REACTION (PCR) AND REVERSE-TRANSCRIPTASE PCR FOR DETERMINING THE FATE OF PHENOL-DEGRADING PSEUDOMONAS-PUTIDA ATCC-11172 IN A BIOAUGMENTED SEQUENCING BATCH REACTOR

The impact of bioaugmentation on the efficacy of an existing microbial population to detoxify phenol in a laboratory-scale sequencing batch reactor was evaluated. Phenol degradation and the persistence and expr ession of the catabolic dmpN gene were studied for 44 days using a com bination of conventional monitoring approaches and molecular technique s. Following addition of the phenol-degrading bacterium, Pseudomonas p utida ATCC 11172, which converts phenol to catechol by the aerobic met a-cleavage pathway, phenol removal in the bioaugmented reactor increas ed and was maintained at 95%-100%. In the unaugmented control reactor, decreased phenol removal was observed. Correspondingly, dmpN DNA, cha racteristic of P. putida ATCC 11172, and its expression were detected in activated sludge biomass from the bioaugmented reactor for over 41 days. The results of this study show that (i) bioaugmentation provides stability in phenol degradation, and (ii) monitoring with molecular t echniques such as the polymerase chain reaction (PCR) and reverse tran scriptase/PCR can successfully assess the state of a bacterium used in bioaugmentation.