Population dynamics and metabolic activity of Pseudomonas abietaniphila BKME-9 within pulp mill wastewater microbial communities assayed by competitive PCR and RT-PCR

Abstract

Resin acids contribute to the acute toxicity of pulp and paper mill effluent. We monitored the abundance and metabolic activity of the resin acid degrader, Pseudomonas abietaniphila BKME-9, within complex communities of laboratory-scale effluent treatment systems using competitive PCR and competitive RT-PCR, targeting the 16S rDNA and rRNA. In continuous culture, a positive linear relationship was found between the rRNA:rDNA ratio and specific growth rate of BKME-9. In batch culture, the rRNA:rDNA ratio peaked briefly during early exponential growth of BKME-9. During continuous growth of an activated sludge community inoculated with BKME-9, the rRNA:rDNA ratio of BKME-9 decreased when the community was stressed with an alkaline pH shock. After the pH shock, the metabolic activity and population of BKME-9 recovered concomitantly with recovery of resin acid removal activity in the system. Thus, BKME-9 has characteristics that could be useful for bioaugmentation of biotreatment systems, and it is possible to monitor the population and activity of BKME-9 in such complex systems.