The sulfur depot in the rhizosphere of a common wetland plant, Juncus effusus, can support long-term dynamics of inorganic sulfur transformations
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Sulfur Cycle
Sulfate-Reducing Bacteria
Sulfur Metabolism
The sulfur cycle is an important and complex biogeochemical cycle involving both inorganic and organic species in both oxic and anoxic environments. However, due to the lack of research regarding the sulfur cycle in freshwater systems, the contributions of organic sulfur compounds to the sulfur cycle are underappreciated. Recent studies have suggested organic sulfur compounds likely fuels sulfate reduction, especially in low-sulfate oligotrophic freshwater systems, through a possible cryptic sulfur cycle. To determine the contributions that organic sulfur compounds may have in this environment, we used Lake Superior sediment to analyze for the presence of and expression of sulfur cycling genes. In these metagenomes, we found genes for sulfur reduction, oxidation and organic sulfur compound degradation. Metabolic pathway analysis showed presence of not only organic sulfur compounds contributing to the sulfur cycle, but tetrathionate, thiosulfate, and polysulfides playing a role as well. Using Lake Superior sediments, we also conducted sediment incubations to measure the biotransformation capability of sulfur-containing amino acids, sulfonates, and an analog for a common sulfolipid. Taurine and sodium dodecyl sulfate produced higher sulfate values in incubations, suggesting that microbes prefer sulfonates over sulfur-containing amino acids, in addition to a possible partiality towards oxidized organic sulfur compounds over reduced forms regarding sulfate production. The preference of sulfonates is supported by the commonality of taurine genes present as well as the low, but present transcription values of sulfoacetaldehyde degradation. While sulfur-containing amino acids do not produce sulfate values near that of sulfonates or sulfolipids, there are still present and transcriptionally active genes that can contribute to sulfate reduction in the system. Regarding methyl-sulfurs, metatranscriptomic data shows that methyl-mercaptan (intermediate within dimethyl sulfide and methionine degradation) degradation is transcriptionally active across genomes. By combining biotransformation incubation data, metagenomics, and metatranscriptomics, we analyzed how methylated sulfurs, sulfur-containing amino acids and sulfonates can fuel a sulfur cycle in a low-sulfate environment, informing us on how pathways may have operated in our Earth’s geologic past.
Sulfur Cycle
Sulfur Metabolism
Biogeochemical Cycle
Sulfate-Reducing Bacteria
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Sulfur Cycle
Sulfur Metabolism
Sulfate-Reducing Bacteria
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AbstrcatHydrogen sulfide is a kind of harmful gas,which is mainly produced by sulfate-reducing bacteria (SRB) under the anaerobic environment.Accumulating in a large amount of hydrogen sulfide can not only cause the corrosion of steel and other metallic materials, but also make people and various kinds of living beings (especially aquatic living beings) to be poisonous.The physical-chemical property and the harm of hydrogen sulfide are presented.Its producing mechanism in anaerobic environment and corresponding qualitative and quantitative detective techniques and methods are defined.Some removing measurements in chemical,biological,physical aspects of hydrogen sulfide are discussed.
Sulfate-Reducing Bacteria
Hydrogen sulphide
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Abstract Zero-valent sulfur (ZVS) is a critical intermediate in the biogeochemical sulfur cycle. Up to date, sulfur oxidizing bacteria have been demonstrated to dominate the formation of ZVS. In contrast, formation of ZVS mediated by sulfate reducing bacteria (SRB) has been rarely reported. Here, we report for the first time that a typical sulfate reducing bacterium Desulfovibrio marinus CS1 directs the formation of ZVS via sulfide oxidation. In combination with proteomic analysis and protein activity assays, thiosulfate reductase (PhsA) and sulfide: quinone oxidoreductase (SQR) were demonstrated to play key roles in driving ZVS formation. In this process, PhsA catalyzed thiosulfate to form sulfide, which was then oxidized by SQR to form ZVS. Consistently, the expressions of PhsA and SQR were significantly up-regulated in strain CS1 when cultured in the deep-sea cold seep, strongly indicating strain CS1 might form ZVS in its real inhabiting niches. Notably, homologs of phsA and sqr widely distributed in the metagenomes of deep-sea SRB. Given the high abundance of SRB in cold seeps, it is reasonable to propose that SRB might greatly contribute to the formation of ZVS in the deep-sea environments. Our findings add a new aspect to the current understanding of the source of ZVS.
Sulfur Cycle
Sulfate-Reducing Bacteria
Cold seep
Biogeochemical Cycle
Oxidizing agent
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Microbial organic sulfur mineralization to sulfate in terrestrial systems is poorly understood. The process is often missing in published sulfur cycle models. Studies on microbial sulfur cycling have been mostly centered on transformations of inorganic sulfur, mainly on sulfate-reducing and inorganic sulfur-oxidizing bacteria. Nevertheless, organic sulfur constitutes most sulfur in soils. Recent reports demonstrate that the mobilization of organic-bound-sulfur as sulfate in terrestrial environments occurs preferentially under high temperatures and thermophilic Firmicutes bacteria play a major role in the process, carrying out dissimilative organic-sulfur oxidation. So far, the determinant metabolic reactions of such activity have not been evaluated. Here, in silico analysis was performed on the genomes of sulfate-producing thermophilic genera and mesophilic low-sulfate producers, revealing that highest sulfate production is related to the simultaneous presence of metabolic pathways leading to sulfite synthesis, similar to the ones found in mammalian cells. Those pathways include reverse transsulfuration reactions (tightly associated with methionine cycling), and the presence of aspartate aminotransferases (ATs) with the potential of 3-sulfinoalanine AT and cysteine AT activity, which ultimately leads to sulfite production. Sulfite is oxidized to sulfate by sulfite oxidase, this enzyme is determinant in sulfate synthesis, and it is absent in many mesophiles.
Sulfur Cycle
Sulfur Metabolism
Sulfate-Reducing Bacteria
Sulfite oxidase
Mesophile
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Hydrogen sulfide is emitted by higher plants in response to the uptake of sulfate, sulfur dioxide, L- and D-cysteine. For each of these sulfur sources a different pathway of synthesis of hydrogen sulfide has been established. Apparently, these pathways are part of an intracellular sulfur cycle that may operate to maintain the cysteine concentration in plant cells at the observed low level when sulfur is present in excess. Hydrogen sulfide emission by higher plants is not a laboratory artefact but is also observed in the field. Though a proper quantification of the volatile sulfur emitted on a global scale can not be obtained from the data presently available, hydrogen sulfide emission by higher plants seems to be a significant contribution to the biogeochemical cycle of sulfur.
Sulfur Cycle
Biogeochemical Cycle
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Sulfur Metabolism
Sulfur Cycle
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Organosulfur compounds
Sulfur Metabolism
Sulfur Cycle
Methanethiol
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Sulfur is both crucial to life and a potential threat to health. While colonic sulfur metabolism mediated by eukaryotic cells is relatively well studied, much less is known about sulfur metabolism within gastrointestinal microbes. Sulfated compounds in the colon are either of inorganic (e.g., sulfates, sulfites) or organic (e.g., dietary amino acids and host mucins) origin. The most extensively studied of the microbes involved in colonic sulfur metabolism are the sulfate-reducing bacteria (SRB), which are common colonic inhabitants. Many other microbial pathways are likely to shape colonic sulfur metabolism as well as the composition and availability of sulfated compounds, and these interactions need to be examined in more detail. Hydrogen sulfide is the sulfur derivative that has attracted the most attention in the context of colonic health, and the extent to which it is detrimental or beneficial remains in debate. Several lines of evidence point to SRB or exogenous hydrogen sulfide as potential players in the etiology of intestinal disorders, inflammatory bowel diseases (IBDs) and colorectal cancer in particular. Generation of hydrogen sulfide via pathways other than dissimilatory sulfate reduction may be as, or more, important than those involving the SRB. We suggest here that a novel axis of research is to assess the effects of hydrogen sulfide in shaping colonic microbiome structure. Clearly, in-depth characterization of the microbial pathways involved in colonic sulfur metabolism is necessary for a better understanding of its contribution to colonic disorders and development of therapeutic strategies.
Sulfur Metabolism
Sulfate-Reducing Bacteria
Microbial Metabolism
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[Objective]To analyze the diversity and spatial characteristic of microbial community of sulfur cycle in Lake Erhai sediments.[Methods]Dumping culture was performed to count the numbers of sulfate-reducing bacteria and sulfate-oxi-dizing bacteria in the sediments of Lake Erhai,and PCR was utilized to analyze sulfate-reducing bacteria subgroups.[Results] The spatial distribution of sulfate-reducing bacteria coincided with sulfate-oxidizing bacteria.Three sulfate-reducing bacteria subgroups were detected.Desulfobulbus distributed widely,Desulfotomaculum scattered in the deeper sediments and Desulfococ-cus-Desulfonema-Desulfosarcina spreaded in the lower sediments.[Conclusion]The microbial community composition of sulfur cycle in Lake Ehai sediments is complex.
Sulfur Cycle
Sulfate-Reducing Bacteria
Oxidizing agent
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