Sulfur Reduction Coupled with Anaerobic Ammonium Oxidation Drove Prebiotic Proto-Anabolic Networks

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Studies are limited on microbial-driven sulfurous species reduction coupled with anaerobic ammonium oxidation (Sammox) in a water environment. In this study, thiosulfate-driven Sammox bacteria from Ningbo Critical Zone Observatory (CZO) groundwater, Zhejiang Province, China were enriched and analyzed. The results showed that all three groundwater samples contained bacteria with sulfur reduction, sulfide oxidation-dependent denitrification, and nitrogen fixation abilities. At the genus level, Arcobacter, Flavobacterium, Hydrogenophaga, Gemmobacter, Pseudomonas, and Methylophilus have higher abundance in three samples. Proteobacteria accounted for a large proportion at the phylum level in all groundwater samples, and are often found in the sulfate reduction coupled with the ammonium oxidation process. Sammox can be performed by synergistic action of bacteria, which may convert ammonium to nitrite and thiosulfate to sulfide. Arcobacter was the dominant bacteria in the medium to remove nitrite and thiosulfate/sulfide. Sammox may also be performed by a single bacterium, belonging to Planctomycetes, Verrucomicrobia, and Chlamydiae superphylum. Overall, bacterial-mediated Sammox exists in the environment of CZO groundwater.

Section: ■ Discussionmentioning

confidence: 99%

Section: ■ Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Bacteria Involved in Thiosulfate Reduction Coupled with Anaerobic Ammonium Oxidation in the Critical Zone Groundwater

Zhou

et al. 2021

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Thiosulfate Reduction Coupled with Anaerobic Ammonium Oxidation by Ralstonia sp. GX3-BWBA

Xiao

et al. 2020

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Thiosulfate reduction coupled with anaerobic ammonium oxidation (Sammox) has been recently reported as an ancient metabolic pathway. Therefore, the Sammox microbes are well worth discovering. In this study, we isolated and identified a mixtrophic Sammox bacterium, Ralstonia sp. GX3-BWBA. Nitrite was an intermediate product of both thiosulfate-and sulfatefueled Sammox metabolism, while nitrogen gas was the end product. Ralstonia sp. GX3-BWBA prefers thiosulfate to sulfate as an electron acceptor for coupling anaerobic ammonium oxidation. Genomic analysis of Ralstonia sp. GX3-BWBA implied that this ancient metabolism in modern microbes might contain two stages according to ammonium transformation, oxidation of ammonium to nitrite and denitrification. The incomplete reductive tricarboxylic acid cycle and reductive acetyl-CoA pathway were all identified Ralstonia sp. GX3-BWBA metabolic networks, which were responsible for chemolithotrophic metabolism. Ralstonia sp. GX3-BWBA contains no ATP sulfurylase (Sat)-coding gene, suggesting that sulfate reduction in sulfate-fueled Sammox is different from dissimilatory sulfate reduction. Ferredoxin oxidoreductase or other iron−sulfur enzymes encoded by genes with unknown sequences may be involved in thiosulfate reduction in the Sammox process. Our findings regarding the Sammox microbes provide microbiological evidence for this unique feature of life.

Adaptive Changes in Bacterial and Archaeal Community Structures and Functions Occur under Primordial Conditions

Wu,

He,

Qiu

et al. 2024

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The microorganisms responsible for driving the Anammox and Sammox processes may have ancient origins and remain poorly understood. In this research, we enriched the microorganisms from paddy soils and marine sediments under Anammox and Sammox conditions to investigate the shifts in their structure and functions. The community structure showed significant differences between enrichment cultures of paddy soils and marine sediments under the Anammox and Sammox conditions. Among samples from paddy soils, Proteobacteria, Nitrospirota, Verrucomicrobiota, Gemmatimonadata, and Euryarchaeota accounted for a larger proportion under Anammox culture conditions, while Firmicutes, Bacteroidota, Chloroflexi, Planctomycetota, Acidobacteriota, Crenarchaeota, and Nanoarchaeota accounted for a larger proportion under Sammox culture conditions. Among samples from marine sediments, Proteobacteria, Bacteroidota, and Euryarchaeota accounted for a larger proportion in the Anammox culture conditions, while Firmicutes, Chloroflexi, Crenarchaeota, and Nanoarchaeota accounted for a larger proportion in Sammox culture conditions. Genes associated with assimilatory sulfate reduction, nitrate reduction, and denitrification pathways were more abundant under Anammox culture conditions, whereas genes related to dissimilatory sulfate reduction and nitrification pathways were more prevalent under Sammox culture conditions. These findings provide valuable insights into the ecological conditions and microbial species of the primordial era and may aid in the searching for extraterrestrial life.