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Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation
Published on: July 13, 2012
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Reductive acetogenesis is a dominant process in the ruminant hindgut.
Qiushuang Li1,2, Jiabin Huo1,2, Gaofeng Ni3
1Key Laboratory for Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.
Microbiome
|January 28, 2025
Summary
Ruminant hindguts, particularly the cecum, show higher levels of hydrogen and acetate, with a significant increase in reductive acetogenic bacteria compared to the rumen. This finding reshapes understanding of hydrogen metabolism and offers potential for livestock methane mitigation.
Area of Science:
- Ruminant microbiology
- Gastrointestinal metabolism
- Microbial ecology
Background:
- Ruminant gastrointestinal tracts convert plant biomass to volatile fatty acids (VFAs) for energy.
- The foregut (rumen) microbiome is well-studied, but the hindgut (cecum, colon) microbiome is less understood, especially regarding hydrogen metabolism.
- Understanding hindgut microbial communities is crucial for ruminant physiology and methane mitigation.
Purpose of the Study:
- To comparatively investigate the composition, capabilities, and activities of rumen and cecum microbiomes in goats.
- To elucidate the distinct pathways of hydrogen metabolism in the rumen versus the cecum.
- To assess the potential of hindgut acetogenesis for livestock methane mitigation strategies.
Main Methods:
- In situ measurements of dissolved hydrogen and acetate in rumen and cecum.
- Microbial profiling and genome-resolved metagenomic analysis.
- In vitro experiments to assess hydrogen metabolism pathways.
- Comparative analysis across multiple ruminant species.
Main Results:
- Cecum exhibited significantly higher levels of dissolved hydrogen and acetate compared to the rumen.
- Cecum harbored greater abundance of mucin-degraders and hydrogen producers; rumen had more fibrolytic bacteria and methanogens.
- Reductive acetogenic bacteria were 12-fold more abundant in the cecum, phylogenetically and functionally distinct from rumen acetogens.
- In vitro studies showed increased acetate production and reduced methanogenesis in the cecum, with conserved hindgut acetogen enrichment across species.
Conclusions:
- Acetogenesis is significantly enriched in the ruminant cecum, distinct from rumen hydrogen metabolism.
- Findings reshape understanding of ruminant hydrogen metabolism and its role in VFA production.
- Enrichment of hindgut acetogens offers a potential target for managing livestock methane emissions.
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