Butyrate Conversion by Sulfate-Reducing and Methanogenic Communities from Anoxic Sediments of Aarhus Bay, Denmark

Abstract

The conventional perception that the zone of sulfate reduction and methanogenesis are separated in high- and low-sulfate-containing marine sediments has recently been changed by studies demonstrating their co-occurrence in sediments. The presence of methanogens was linked to the presence of substrates that are not used by sulfate reducers. In the current study, we hypothesized that both groups can co-exist, consuming common substrates (H2 and/or acetate) in sediments. We enriched butyrate-degrading communities in sediment slurries originating from the sulfate, sulfate–methane transition, and methane zone of Aarhus Bay, Denmark. Sulfate was added at different concentrations (0, 3, 20 mM), and the slurries were incubated at 10 °C and 25 °C. During butyrate conversion, sulfate reduction and methanogenesis occurred simultaneously. The syntrophic butyrate degrader Syntrophomonas was enriched both in sulfate-amended and in sulfate-free slurries, indicating the occurrence of syntrophic conversions at both conditions. Archaeal community analysis revealed a dominance of Methanomicrobiaceae. The acetoclastic Methanosaetaceae reached high relative abundance in the absence of sulfate, while presence of acetoclastic Methanosarcinaceae was independent of the sulfate concentration, temperature, and the initial zone of the sediment. This study shows that there is no vertical separation of sulfate reducers, syntrophs, and methanogens in the sediment and that they all participate in the conversion of butyrate.

Ice Cover Influences Redox Dynamics in Prairie Pothole Wetland Sediments

“…The observed rise of the sub‐oxic/anoxic depth to just below or above the SWI during ice‐on (Figure 4) may promote the biogeochemical conditions and microbial interactions required to sustain high methane concentrations in the presence of high rates of sulfate reduction observed in these porewaters (Dalcin Martins et al., 2017). This process whereby methanogenesis occurs concurrently with sulfate reduction has also been reported by others in marine systems as well and is an example of processes that do not follow the “redox ladder” paradigm in sediments (Egger et al., 2016; Maltby et al., 2016, Mitterer, 2010; Ozuolmez et al., 2020; Sela‐Adler et al., 2017, and references therein). Yet despite these high effluxes of methane, PPR wetlands are still considered net carbon sinks due to their ability to store large amounts of soil organic carbon and are capable of sequestering 3.25 Mg of carbon ha −1 yr −1 (Badiou et al., 2011).…”

Lower values of a novel index of Vagal-Neuroimmunomodulation are associated to higher all-cause mortality in two large general population samples with 18 year follow up

“…Importantly, the cytokine profile described in COVID-19-Patients shows large similarities with the cytokine profile of α7nAChRs dysregulated macrophages i.e. massively secreting IL-1β, IL-6, tumor necrosis factor alpha (TNF α) α and IL-18 among others 20 – 22 . In consequence, the stimulation of the vagus nerve may prevent the damaging effects of cytokine release in experimental sepsis, endotoxemia, ischemia/reperfusion injury, hemorrhagic shock, arthritis, and other inflammatory syndromes.…”

“…Consequently, several α7nAChR agonists have been identified as experimental anti-inflammatory therapeutics with potential for clinical development 18 . Here, cholinergic agonists can inhibit cytokine synthesis and protect against cytokine-mediated diseases such as the cytokine release syndrome (CRS, also described as cytokine storm) seen in COVID-19 patients 20 . Importantly, the cytokine profile described in COVID-19-Patients shows large similarities with the cytokine profile of α7nAChRs dysregulated macrophages i.e.…”

Trimethylornithine Membrane Lipids: Discovered in Planctomycetes and Identified in Diverse Environments

“…Trimethylornithines were identified in the oxic, micro-oxic, and anoxic layers of Northern wetland peat [ 49 ], therefore, it is consistent to observe TMOs in oxic lake waters. Conversely, TMOs were later identified in enrichment cultures of anoxic methanogenic sediment from Arhus Bay, Denmark [ 58 ], akin to the presence of TMOs in anoxic methanogenic peat. Among the enrichment cultures that contained TMOs, the cultures that received sulfate amendments had higher TMO relative abundances than the TMO-containing enrichment culture that did not receive additional sulfate.…”