Inhibition of Microbial Methane Oxidation by 2-Chloro-6-Methylpyridine

• DOI: 10.1101/2022.10.13.512149
• Publication Date: 2022-10-14T12:40:16Z
• Authors: Edward J. O’Loughlin; Dionysios A. Anto...; Kristin K. Arend; Theodore M. Flynn; Jason C. Koval; Sarah M. Owens
• Keywords: Verrucomicrobia; Acidobacteria; Microcosm; Methane Monooxygenase

Abstract Several pyridine derivatives including the pesticide nitrapyrin [2-chloro-6-(trichloromethyl) pyridine] are strong inhibitors of methane monooxygenase, a key enzyme aerobic (CH 4 ) oxidation. In this study we examined effects 2-chloro-6-methylpyridine (2C6MP) concentration on CH oxidation and development populations putative methanotrophs in sediment from Old Woman Creek, freshwater estuary Huron Co., Ohio. Experimental systems were prepared serum bottles containing minimal medium with headspace 20% O 2 10% . The microcosms spiked 2C6MP to achieve concentrations 0, 0.1, 1, or 10 mM inoculated sediment. When decreased < 2%, subsamples taken for DNA extraction sequencing 16S rRNA gene amplicons. There was effect at 1 mM, but complete inhibition > 20 months observed mM. ANOSIM weighted UniFrac distances between groups triplicate samples supported primary distinction inoculum relative enrichments (R=0.999) secondary versus those without (R=0.464 [0.1 mM]; R=0.894 [1 mM]). dominated by members Proteobacteria (49.9±1.5%), lesser extent Bacteroidetes (8.8±0.2%), Acidobacteria (8.9±0.4%), Verrucomicrobia (4.4±0.3%). 2C6MP, expanded comprise 65–70% total. absence inhibitor, Methylococcaceae Methylophilaceae increased abundance 0.1% 8.5±1.0% 13.4±2.3%, total community respectively. At both 0.1 much less abundant, representing 3.3±0.5% 2.8±3.3% No seen lower higher taxon only 7.8±1.1% contrast, Crenotrichaceae , another group oxidizers, greater amounts 8.6±3.6% 12.0±4.5% compared 4.1±0.4% when no inhibitor present. These results clearly show changes amount