Biology subjects

Sanchez-Andrea, I.

Publications and source records attributed to Sanchez-Andrea, I..

3 recordsLinked to original sources

bioRxiv2024

Physiological stress response to sulfide exposure of freshwater anaerobic methanotrophic archaea

Freshwater wetlands and coastal sediments are becoming hotspots for the emission of the greenhouse gas methane. Eutrophication-induced deposition of organic matter leads to elevated methanogenesis and sulfate reduction, thereby increasing the concentrations of methane and toxic sulfide, respectively. However, the effects of sulfide stress on the anaerobic methanotrophic biofilter have not been well explored. Here, we show how an enrichment culture dominated by the freshwater anaerobic methane-oxidizing archaeon Candidatus (Ca.) Methanoperedens responds to short-term and long-term exposure to sulfide in a bioreactor. The methane-oxidizing activity decreased to 45% and 20% but partially recovered to 70% and 30% within 5 days after short- and long-term sulfide exposure, respectively. Metagenomics indicated that Ca. Methanoperedens remained dominant in the enrichment throughout the entire experiment. The first short-term sulfide pulse led to increased expression of genes encoding for sulfide detoxification by low abundant community members, whereas long-term exposure resulted in upregulation of Ca. Methanoperedens genes encoding sulfite reductases of Group III (Dsr-LP). Ca. Methanoperedens consumed Polyhydroxyalkanoates during long-term sulfide exposure, possibly to aid in stress adaptation. Together, these results provide a valuable baseline for understanding fundamental ecophysiological adaptations in sulfate- and nitrate-rich aquatic ecosystems. Short synopsis statementThis study investigated how freshwater anaerobic methanotrophic archaea responded to sulfide exposure, revealing a transient inhibition and physiological adaptation mechanisms.

microbiology↗

bioRxiv2024

Methanotrophic flexibility of Ca. Methanoperedens and its interactions with sulfate-1 reducing bacteria in the sediment of meromictic Lake Cadagno

The greenhouse gas methane is an important contributor to global warming, with freshwater sediments representing important potential methane sources. Anaerobic methane-oxidizing archaea mitigate methane release into the atmosphere by coupling the oxidation of methane to the reduction of extracellular electron acceptors or through interspecies electron transfer with microbial partners. Understanding their metabolic flexibility and microbial interactions is crucial to assess their role in global methane cycling. Here, we investigated anoxic sediments of the meromictic freshwater Lake Cadagno (Switzerland), where Ca. Methanoperedens and sulfate-reducing bacteria co-occur, with metagenomics and long-term incubations. Incubations were performed with different electron acceptors, revealing that manganese oxides supported highest CH4 oxidation potential but enriched for Ca. Methanoperedens phylotypes that were hardly present in the inoculum. Combining data from the inoculum and incubations, we obtained five Ca. Methanoperedens genomes, each harboring different extracellular electron transfer pathways. In a reconstructed Desulfobacterota QYQD01 genome we observed large multi-heme cytochromes, type IV pili, and a putative loss of hydrogenases, suggesting facultative syntrophic interactions with Ca. Methanoperedens. We also screened for putative extrachromosomal elements in the Ca. Methanoperedens genomes, including BORGs. This research deepens our understanding of the metabolic flexibility and potential interspecific interactions of Ca. Methanoperedens in freshwater lakes.

microbiology↗

bioRxiv2024

Biological S0 reduction at neutral (pH 6.9) and acidic (pH 3.8) conditions: Performance and microbial community shifts in a H2/CO2-fed bioreactor

Sulfidogenesis is a promising technology for the selective recovery of chalcophile bulk metals (e.g. Cu, Zn, and Co) from metal-contaminated waters such as acid mine drainage (AMD) and metallurgy waste streams. The use of elemental sulfur (S0) instead of sulfate (SO42-) as electron acceptor reduces electron donor requirements four-fold, lowering process costs, and expands the range of operating conditions to more acidic pH. We previously reported autotrophic S0 reduction using an industrial mesophilic granular sludge as inoculum under thermoacidophilic conditions. Here, we examined the effect of pH on the S0 reduction performance of the same inoculum, in a continuously fed gas-lift reactor run at 30 {degrees}C under neutral (pH 6.9) and acidic (pH 3.8) conditions. Steady-state volumetric sulfide production rates (VSPR) dropped 2.3-fold upon transition to acidic pH, from 1.79 {+/-} 0.18 g{middle dot}L-1{middle dot}d-1 S2-{middle dot}to 0.71 {+/-} 0.07 g{middle dot}L-1{middle dot}d-1 S2-{middle dot} Microbial community analysis via 16S rRNA gene amplicon sequencing showed that at pH 6.9, the S0-reducing genera Sulfurospirillum, Sulfurovum, Desulfurella, and Desulfovibrio were present at the highest relative abundance, while at pH 3.9 Desulfurella dominated the sequenced reads. The detection of acetic acid and the relative abundance of Acetobacterium at pH 6.9 pointed towards acetogenesis, explaining the dominance of the heterotrophic genus Sulfurospirillum in this H2 and CO2-fed bioreactor.

microbiology↗