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A pathway for D-cysteinolate degradation in sulfate- and sulfite-reducing bacteria
Xumei Liu1, Yiling Hu1, Junwei An2
1New Cornerstone Science Laboratory, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China; Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin, China; Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.
The Journal of Biological Chemistry
|December 14, 2025
Summary
Researchers discovered a new pathway for D-cysteinolate degradation in gut bacteria. This finding is crucial for understanding sulfur metabolism and hydrogen sulfide (H2S) production from marine foods in the human gut microbiome.
Area of Science:
- Microbiology
- Environmental Science
- Biochemistry
Background:
- Sulfonates are prevalent environmental compounds crucial for sulfur metabolism.
- Sulfate- and sulfite-reducing bacteria produce hydrogen sulfide (H2S) in anaerobic environments.
- D-cysteinolate is abundant in marine ecosystems, but its anaerobic degradation is unknown.
Purpose of the Study:
- Identify and characterize the anaerobic D-cysteinolate degradation pathway.
- Investigate the role of this pathway in environmental and gut bacteria.
- Elucidate the biochemical steps involved in D-cysteinolate breakdown.
Main Methods:
- Genomic analysis to identify the gene cluster.
- Biochemical assays to characterize enzyme activities.
- Culturing of sulfate- and sulfite-reducing bacteria from environmental and gut samples.
Main Results:
- A novel gene cluster for D-cysteinolate degradation was identified in bacteria.
- The pathway involves epimerization and oxidation of D-cysteinolate to L-cysteate.
- Further degradation yields ammonia, pyruvate, and sulfite, ultimately leading to H2S production.
Conclusions:
- The study reveals the complete anaerobic degradation pathway for D-cysteinolate.
- This pathway is present in bacteria from marine environments and the human gut.
- Findings provide a basis for understanding H2S production from marine foods in the gut microbiome.
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