Mussmann Marc

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Mussmann
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Marc
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  • Preprint
    Transcriptomic and proteomic insight into the mechanism of cyclooctasulfur‐ versus thiosulfate‐oxidation by the chemolithoautotroph Sulfurimonas denitrificans
    ( 2018-10-25) Götz, Florian ; Pjevac, Petra ; Markert, Stephanie ; McNichol, Jesse C. ; Becher, Dorte ; Schweder, Thomas ; Mussmann, Marc ; Sievert, Stefan M.
    Chemoautotrophic bacteria belonging to the genus Sulfurimonas (class Campylobacteria) were previously identified as key players in the turnover of zero‐valence sulfur, a central intermediate in the marine sulfur cycle. S. denitrificans was further shown to be able to oxidize cyclooctasulfur (S8). However, at present the mechanism of activation and metabolism of cyclooctasulfur is not known. Here, we assessed the transcriptome and proteome of S. denitrificans grown with either thiosulfate or S8 as the electron donor. While the overall expression profiles under the two growth conditions were rather similar, distinct differences were observed that could be attributed to the utilization of S8. This included a higher abundance of expressed genes related to surface attachment in the presence of S8, and the differential regulation of the sulfur‐oxidation multienzyme complex (SOX), which in S. denitrificans is encoded in two gene clusters: soxABXY 1Z 1 and soxCDY 2Z 2. While the proteins of both clusters were present with thiosulfate, only proteins of the soxCDY 2Z 2 were detected at significant levels with S8. Based on these findings a model for the oxidation of S8 is proposed. Our results have implications for interpreting metatranscriptomic and ‐proteomic data and for the observed high level of diversification of soxY 2Z 2 among sulfur‐oxidizing Campylobacteria.
  • Article
    Genus-specific carbon fixation activity measurements reveal distinct responses to oxygen among hydrothermal vent campylobacteria
    (American Society for Microbiology, 2022-01-25) McNichol, Jesse C. ; Dyksma, Stefan ; Mussmann, Marc ; Seewald, Jeffrey S. ; Sylva, Sean P. ; Sievert, Stefan M.
    Molecular surveys of low temperature deep-sea hydrothermal vent fluids have shown that Campylobacteria (previously Epsilonproteobacteria) often dominate the microbial community and that three genera, Arcobacter, Sulfurimonas, and Sulfurovum, frequently coexist. In this study, we used replicated radiocarbon incubations of deep-sea hydrothermal fluids to investigate activity of each genus under three experimental conditions. To quantify genus-specific radiocarbon incorporation, we used newly designed oligonucleotide probes for Arcobacter, Sulfurimonas, and Sulfurovum to quantify their activity using catalyzed-reporter deposition fluorescence in situ hybridization (CARD-FISH) combined with fluorescence-activated cell sorting. All three genera actively fixed CO2 in short-term (∼ 20 h) incubations, but responded differently to the additions of nitrate and oxygen. Oxygen additions had the largest effect on community composition, and caused a pronounced shift in community composition at the amplicon sequence variant (ASV) level after only 20 h of incubation. The effect of oxygen on carbon fixation rates appeared to depend on the initial starting community. The presented results support the hypothesis that these chemoautotrophic genera possess functionally redundant core metabolic capabilities, but also reveal finer-scale differences in growth likely reflecting adaptation of physiologically-distinct phylotypes to varying oxygen concentrations in situ. Overall, our study provides new insights into how oxygen controls community composition and total chemoautotrophic activity, and underscores how quickly deep-sea vent microbial communities respond to disturbances.