Absence of oxygen effect on microbial structure and methane production during drying and rewetting events

Abstract

Natural environments with frequent drainage experience drying and rewetting events that impose fluctuations in water availability and oxygen exposure. These relatively dramatic cycles profoundly impact microbial activity in the environment and subsequent emissions of methane and carbon dioxide. In this study, we mimicked drying and rewetting events by submitting methanogenic communities from strictly anaerobic environments (anaerobic digestors) with different phylogenetic structures to consecutive desiccation events under aerobic (air) and anaerobic (nitrogen) conditions followed by rewetting. We showed that methane production quickly recovered after each rewetting, and surprisingly, no significant difference was observed between the effects of the aerobic or anaerobic desiccation events. There was a slight change in the microbial community structure and a decrease in methane production rates after consecutive drying and rewetting, which can be attributed to a depletion of the pool of available organic matter or the inhibition of the methanogenic communities. These observations indicate that in comparison to the drying and rewetting events or oxygen exposure, the initial phylogenetic structure and the organic matter quantity and quality exhibited a stronger influence on the methanogenic communities and overall microbial community responses. These results change the current paradigm of the sensitivity of strict anaerobic microorganisms to oxygen exposure.

The Selenoproteome as a Dynamic Response Mechanism to Oxidative Stress in Hydrogenotrophic Methanogenic Communities

“…19 However, the class I genera Methanobacterium and Methanobrevibacter have been recurrently detected in oxic soils 24,64−66 and showed resistance against cycles of desiccation and oxygen exposure, along with Methanosarcina. 65,67,68 These results contradict the proposed oxygen sensitivity of class I methanogens and hint at alternative oxygen response mechanisms, 69,70 which could be the incorporation of selenocysteine, as reported in this study. Given that Methanobrevibacter and Methanobacterium are among the most abundant archaea in the human gut, 71 their oxygen tolerance has broader implications for the localization of methanogens within the epithelium 64 and adds to the importance of selenium as a nutrient for human health.…”

River network‐scale drying impacts the spatiotemporal dynamics of greenhouse gas fluxes

“…Therefore, the impact of desiccation on in‐stream microbial and invertebrate decomposer communities, which recovers with time since rewetting, may have subsequently resulted in lower flowing CO 2 and N 2 O fluxes in non‐perennial than perennial sites due to a reduced OM processing capacity. We did not observe an effect of time since rewetting on CH 4 fluxes from non‐perennial sites, which could be because methanogenic communities may not be as sensitive to drying and oxygen exposure as previously thought (Liu et al 2022). Based on our results, future studies could examine the specific mechanisms by which drying has a legacy effect, for example, through downstream transport of OM accumulated in dry reaches, through stress on decomposer communities, or through reduced lateral connectivity.…”

Enhancement of Biodegradability of Chicken Manure via the Addition of Zeolite in a Two-Stage Dry Anaerobic Digestion Configuration

“…Methanosaeta species are speculated to be the predominant CH 4 producers on Earth [ 28 ]. It is well reported that archaeal communities from agricultural waste and sewage sludge digesters are dominated by the obligate acetolactic genus Methanosaeta [ 29 ]. Although Methanosaeta have previously been thought to be restricted to acetate as a substrate for methane production, they have the potential to use carbon dioxide for methane production [ 30 ].…”