Activity of a Methanotrophic Consortium Isolated from Landfill Cover Soil: Response to Temperature, pH, CO2, and Porous Adsorbent

Abstract

ABSTRACTA robust, naturally evolving methanotrophic community in landfill cover soil (LFCS) can be the simplest way to mitigate landfill methane emission. In this study, bacterial community composition in LFCS and methane oxidation potential of enriched methanotrophic consortium, in comparison to that of axenic Methylosinus sporium, was investigated. Growth and methane oxidation of the consortium was studied in liquid phase batch experiments under varying temperature (20–40°C), pH (5–10), headspace CO2, and in presence of porous adsorbent (1.3 cm3 sponge cubes). The 16S rRNA gene analysis revealed presence of both type-I and type-II methanotrophs along with few obligate methylotroph in LFCS. Though the optimal growth condition of the consortium was at 30°C and pH 7, it was more resilient in comparison to M. sporium. With increasing availability of porous adsorbent, methane consumption by the consortium was significantly improved (p < 0.001) reaching a maximum specific methane oxidation rate of 11.4 μmol mg−1 biomass h−1. Thus, inducing naturally thriving methanotrophs in LFCS is a better alternative to axenic methanotrophic culture in methane emission management.