Microbiology & Cell Biology
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Item Acquisition of elemental sulfur by sulfur-oxidising Sulfolobales(Wiley, 2024-08) Fernandes-Martins, Maria C.; Springer, Carli; Colman, Daniel R.; Boyd, Eric S.Elemental sulfur (S80)-oxidising Sulfolobales (Archaea) dominate high-temperature acidic hot springs (>80°C, pH <4). However, genomic analyses of S80-oxidising members of the Sulfolobales reveal a patchy distribution of genes encoding sulfur oxygenase reductase (SOR), an S80 disproportionating enzyme attributed to S80 oxidation. Here, we report the S80-dependent growth of two Sulfolobales strains previously isolated from acidic hot springs in Yellowstone National Park, one of which associated with bulk S80 during growth and one that did not. The genomes of each strain encoded different sulfur metabolism enzymes, with only one encoding SOR. Dialysis membrane experiments showed that direct contact is not required for S80 oxidation in the SOR-encoding strain. This is attributed to the generation of hydrogen sulfide (H2S) from S80 disproportionation that can diffuse out of the cell to solubilise bulk S80 to form soluble polysulfides (Sx2−) and/or S80 nanoparticles that readily diffuse across dialysis membranes. The Sulfolobales strain lacking SOR required direct contact to oxidise S80, which could be overcome by the addition of H2S. High concentrations of S80 inhibited the growth of both strains. These results implicate alternative strategies to acquire and metabolise sulfur in Sulfolobales and have implications for their distribution and ecology in their hot spring habitats.Item Covariation of hot spring geochemistry with microbial genomic diversity, function, and evolution(Springer Science and Business Media LLC, 2024-08) Colman, Daniel R.; Keller, Lisa M.; Arteaga-Pozo, Emilia; Andrade-Barahona, Eva; St. Clair, Brian; Shoemaker, Anna; Cox, Alysia; Boyd, Eric S.The geosphere and the microbial biosphere have co-evolved for ~3.8 Ga, with many lines of evidence suggesting a hydrothermal habitat for life’s origin. However, the extent that contemporary thermophiles and their hydrothermal habitats reflect those that likely existed on early Earth remains unknown. To address this knowledge gap, 64 geochemical analytes were measured and 1022 metagenome-assembled-genomes (MAGs) were generated from 34 chemosynthetic high-temperature springs in Yellowstone National Park and analysed alongside 444 MAGs from 35 published metagenomes. We used these data to evaluate co-variation in MAG taxonomy, metabolism, and phylogeny as a function of hot spring geochemistry. We found that cohorts of MAGs and their functions are discretely distributed across pH gradients that reflect different geochemical provinces. Acidic or circumneutral/alkaline springs harbor MAGs that branched later and are enriched in sulfur- and arsenic-based O2-dependent metabolic pathways that are inconsistent with early Earth conditions. In contrast, moderately acidic springs sourced by volcanic gas harbor earlier-branching MAGs that are enriched in anaerobic, gas-dependent metabolisms (e.g. H2, CO2, CH4 metabolism) that have been hypothesized to support early microbial life. Our results provide insight into the influence of redox state in the eco-evolutionary feedbacks between thermophiles and their habitats and suggest moderately acidic springs as early Earth analogs.Item A concept for international societally relevant microbiology education and microbiology knowledge promulgation in society(Wiley, 2024-05) Timmis, Kenneth et al.; Boyd, Eric S.