Evaluating Different Quantitative PCR Assays to Enumerate Specific Microbial Populations in Anaerobic Digesters Treating Municipal Wastewater Solids

Abstract

The goal of this research was to use and to validate different quantitative polymerase chain reaction (qPCR) assays to quantify the pertinent microbial populations in full-scale anaerobic digesters at municipal wastewater treatment facilities. Methanomicrobiales ($\sim 40\%$ of Archaea) and Methanosarcinales ($\sim 35\%$ of Archaea) were the most dominant methanogenic orders in the mesophilic anaerobic digesters, whereas the Methanobacteriales ($\sim 40\%$ of Archaea) were the most common in the thermophilic anaerobic digester. qPCR results were validated via comparisons with profiles of microbial community composition obtained by PCR-amplified 16S rRNA gene sequences. Exceptionally strong linear correlations ($P<{10}^{-10}$ ) were observed when comparing the microbiome profile with the qPCR results for Archaea, Methanomicrobiales, Methanosarcinales, Methanobacteriales, and Methanosarcinacea. In addition, core communities of both Bacteria and Archaea were observed in the mesophilic anaerobic digesters. This research demonstrates that monitoring microbial groups in full-scale anaerobic digesters is feasible via qPCR, providing the prerequisite tools needed to track and to understand microbial population dynamics in anaerobic digesters.