Lakes are important methane (CH4) sources to the atmosphere, especially eutrophic lakes with cyanobacterial blooms accompanied by volatile sulfur compound (VSC) emissions. CH4 oxidation is a key strategy to mitigate CH4 emission from lakes. In this study, we characterized the fate of CH4-derived carbon and active microbial communities in lake sediments with CS2 used as a typical VSC, based on the investigation of CH4 and VSC fluxes from Meiliang Bay in Lake Taihu. Stable isotope probing microcosm incubation showed that the efficiency of CH4-derived carbon incorporated into organic matter was 21.1% in the sediment with CS2 existence, which was lower than that without CS2 (27.3%). SO42--S was the main product of CS2 oxidation under aerobic condition, accounting for 59.3-62.7% of the input CS2-S. CS2 and CH4 coexistence led to a decrease of methanotroph and methylotroph abundances and stimulated the production of extracellular polymeric substances. CS2 and its metabolites including total sulfur, SO42- and acid volatile sulfur acted as the main drivers influencing the active microbial community structure in the sediments. Compared with α-proteobacteria methanotrophs, γ-proteobacteria methanotrophs Methylomicrobium, Methylomonas, Crenothrix and Methylosarcina were more dominant in the sediments. CH4-derived carbon mainly flowed into methylotrophs in the first stage. With CH4 consumption, more CH4-derived carbon flowed into non-methylotrophs. CS2 could prompt more CH4-derived carbon flowing into non-methanotrophs and non-methylotrophs, such as sulfur-metabolizing bacteria. These findings can help elucidate the influence of VSCs on microorganisms and provide insights to carbon fluxes from eutrophic lake systems.
Keywords: CS(2) oxidation rate; Methane oxidation; Methanotrophs; Sulfur-containing compounds; Sulfur-metabolizing microorganisms.
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