Phenotypic fingerprinting of microbial communities in wastewater treatment systems

Community-level characterization of microbial biomass from a municipal activated sludge plant, and two bleached kraft mill effluent (BKME) treatment systems, an oxygenated activated sludge system and an aerated lagoon system, was carried out using the BIOLOG redox-based carbon-substrate utilization assay. Several extraction procedures for separating microbial cells from the dark colloidal samples, including culture enrichment, homogenization, gravel agitation and sonication, were evaluated in order to overcome interference with colour development in the assay. Optimal microbial recovery was achieved by homogenization in the presence of deflocculating agents, sodium pyrophosphate and Tween 80. Principal component analysis was used to differentiate among the microbial communities in the wastewater treatment systems. Biomass obtained from each of the reactors displayed different composite metabolic profiles suggesting a unique indigenous microbial population in each system. Characterization of separate bacterial and protozoal components of one community also showed that each fraction displayed different substrate utilization patterns. Substitution of the already prepared BIOLOG panel substrates with individual chemicals typically associated with BKME allowed for the determination of biodegradation potential in wastewater treatment systems.