• Asian-Australasian Journal of Animal Sciences
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• v.32 no.12
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• pp.1907-1913
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• 2019

Objective: Homoacetogens play important roles in the production of acetate in the large intestine of monogastric mammals. However, their diversity in the porcine large intestine is still unknown. Marker gene analysis was performed to assess the effects of energy level on the diversity and population densities of homoacetogens in porcine feces. Methods: Crossbred pigs were fed high or low energy-level diets. The high-intake (HI) diet was sufficient to allow a daily gain of 1.2 kg. The low-intake (LI) diet provided 0.6 times the amount of energy as the HI diet. Genetic diversity was analyzed using formyltetrahydrofolate synthetase gene (FHS) clone libraries derived from fecal DNA samples. FHS DNA copy numbers were quantified using real-time polymerase chain reaction. Results: A wide variety of FHS sequences was recovered from animals in both treatments. No differences in FHS clone libraries between the HI and LI groups were found. During the experimental period, no significant differences in the proportion of FHS copy numbers were observed between the two treatment groups. Conclusion: This is the first reported molecular diversity analysis using specific homoacetogen marker genes from the large intestines of pigs. There was no observable effect of feed intake on acetogen diversity.

• Journal of Korean Society on Water Environment
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• v.16 no.4
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• pp.541-554
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• 2000

Experimental study of anaerobic digestion process combined with and without the submerged separation membrane was investigated by using laboratory-scale reactor at the hydraulic retention time of 0.5 day and 1.0 day. The removal efficiencies of carbohydrate at the digester without and with membrane were 84.4 to 86.8 % and 99.6 to 99.7 %, respectively, and the methane gas recovery efficiencies were 0.4 to 1.2 % and 12.3 to 28.7 %. According to the measurement by the most probable numbers method. the numbers of various groups of bacteria in the digesters with membrane were enumerated in the following ranges ; acidogens : $1.7{\times}10^9$ to $5.0{\times}10^9MPN/m{\ell}$, homoacetogens : $5.0{\times}10^7$ to $2.4{\times}10^8MPN/m{\ell}$, $H_2$-utilizing methanogens : $1.3{\times}10^7$ to $9.2{\times}10^8MPN/m{\ell}$, and acetate-utilizing methanogens : $2.3{\times}10^6$ to $2.0{\times}10^8MPN/m{\ell}$. The number of methanogens at the digester with membrane increased by approximately $10^2$ to $10^4$ times in comparison with that of the digester without membrane.

• Animal Bioscience
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• v.37 no.2_spc
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• pp.323-336
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• 2024

Molecular hydrogen (H₂) and formate (HCOO^-) are metabolic end products of many primary fermenters in the rumen ecosystem. Both play a vital role in fermentation where they are electron sinks for individual microbes in an anaerobic environment that lacks external electron acceptors. If H₂ and/or formate accumulate within the rumen, the ability of primary fermenters to regenerate electron carriers may be inhibited and microbial metabolism and growth disrupted. Consequently, H₂- and/or formate-consuming microbes such as methanogens and possibly homoacetogens play a key role in maintaining the metabolic efficiency of primary fermenters. There is increasing interest in identifying approaches to manipulate the rumen ecosystem for the benefit of the host and the environment. As H₂ and formate are important mediators of interspecies interactions, an understanding of their production and utilization could be a significant starting point for the development of successful interventions aimed at redirecting electron flow and reducing methane emissions. We conclude by discussing in brief ruminant methane mitigation approaches as a model to help understand the fate of H₂ and formate in the rumen ecosystem.