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Ammonium influences kinetics and structure of methanotrophic consortia
- López, Juan C., Porca, Estefanía, Collins, Gavin, Clifford, Eoghan, Quijano, Guillermo, Muñoz, Raúl
- Waste management 2019 v.89 pp. 345-353
- Methylobacter, Methylocystis, Methylomicrobium, Methylosarcina, ammonium, biodegradation, biotechnology, inoculum, landfills, leachates, methane, methanotrophs, microbial ecology, oxidation, soil, waste management
- The literature is conflicted on the influence of ammonium on the kinetics and microbial ecology of methanotrophy. In this study, methanotrophic cultures were enriched, under ammonium concentrations ranging from 0 to 200 mM, from an inoculum comprising leachate and top-cover soil from a landfill. Specific CH4 biodegradation rates were highest (7.8 × 10−4 ± 6.0 × 10−5 gCH4 gX−1 h−1) in cultures enriched at 4 mM NH4+, which were mainly dominated by type II methanotrophs belonging to Methylocystis spp. Lower specific CH4 oxidation rates (average values of 1.8–3.6 × 10−4 gCH4 gX−1 h−1) were achieved by cultures enriched at higher NH4+ concentrations (20 and 80 mM), and had higher affinity for CH4 compared to 4 mM enrichments. These lower affinities were attributed to lower diversity dominated by type I methanotrophs, of the Methylosarcina, Methylobacter and Methylomicrobium genera, encountered with increasing concentrations of NH4+. The study indicates that CH4 oxidation biotechnologies applied at low NH4+ concentrations can support efficient abatement of CH4 and high diversity of methanotrophic consortia, whilst enriching type II methanotrophs.