Use of Stable-Isotope Probing, Full-Cycle rRNA Analysis, and Fluorescence In Situ Hybridization-Microautoradiography to Study a Methanol-Fed Denitrifying Microbial Community

Abstract

A denitrifying microbial consortium was enriched in an anoxically operated, methanol-fed sequencing batch reactor (SBR) fed with a mineral salts medium containing methanol as the sole carbon source and nitrate as the electron acceptor. The SBR was inoculated with sludge from a biological nutrient removal activated sludge plant exhibiting good denitrification. The SBR denitrification rate improved from less than 0.02 mg of NO3--N mg of mixed-liquor volatile suspended solids (MLVSS)-1 h-1 to a steady-state value of 0.06 mg of NO3--N mg of MLVSS -1 h-1 over a 7-month operational period. At this time, the enriched microbial community was subjected to stable-isotope probing (SIP) with [13C]methan..