Effects of type of substrate and dilution rate on fermentation in serial rumen mixed cultures.

Autor: Ungerfeld EM; Centro Regional de Investigación Carillanca, Instituto de Investigaciones Agropecuarias, Vilcún, Chile., Cancino-Padilla N; Centro Regional de Investigación Carillanca, Instituto de Investigaciones Agropecuarias, Vilcún, Chile., Vera-Aguilera N; Centro Regional de Investigación Carillanca, Instituto de Investigaciones Agropecuarias, Vilcún, Chile., Scorcione MC; Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina., Saldivia M; Instituto de Ciencia Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile., Lagos-Pailla L; Instituto de Ingeniería Agraria y Suelos, Facultad de Ciencias Agrarias y Alimentarias, Universidad Austral de Chile, Valdivia, Chile.; Centro de Investigación de Suelos Volcánicos, Universidad Austral de Chile, Valdivia, Chile.; Centro de Humedales Río Cruces, Valdivia, Chile., Vera M; Instituto de Ingeniería Agraria y Suelos, Facultad de Ciencias Agrarias y Alimentarias, Universidad Austral de Chile, Valdivia, Chile., Cerda C; Departamento de Procesos Industriales, Universidad Católica de Temuco, Temuco, Chile., Muñoz C; Centro Regional de Investigación Remehue, Instituto de Investigaciones Agropecuarias, Osorno, Chile., Urrutia N; Centro Regional de Investigación Remehue, Instituto de Investigaciones Agropecuarias, Osorno, Chile., Martínez ED; Instituto de Ciencia Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile.
Jazyk: angličtina
Zdroj: Frontiers in microbiology [Front Microbiol] 2024 Feb 09; Vol. 15, pp. 1356966. Date of Electronic Publication: 2024 Feb 09 (Print Publication: 2024).
DOI: 10.3389/fmicb.2024.1356966
Abstrakt: Forages and concentrates have consistently distinct patterns of fermentation in the rumen, with forages producing more methane (CH 4 ) per unit of digested organic matter (OM) and higher acetate to propionate ratio than concentrates. A mechanism based on the Monod function of microbial growth has been proposed to explain the distinct fermentation pattern of forages and concentrates, where greater dilution rates and lower pH associated with concentrate feeding increase dihydrogen (H 2 ) concentration through increasing methanogens growth rate and decreasing methanogens theoretically maximal growth rate, respectively. Increased H 2 concentration would in turn inhibit H 2 production, decreasing methanogenesis, inhibit H 2 -producing pathways such as acetate production via pyruvate oxidative decarboxylation, and stimulate H 2 -incorporating pathways such as propionate production. We examined the hypothesis that equalizing dilution rates in serial rumen cultures would result in a similar fermentation profile of a high forage and a high concentrate substrate. Under a 2 × 3 factorial arrangement, a high forage and a high concentrate substrate were incubated at dilution rates of 0.14, 0.28, or 0.56 h -1 in eight transfers of serial rumen cultures. Each treatment was replicated thrice, and the experiment repeated in two different months. The high concentrate substrate accumulated considerably more H 2 and formate and produced less CH 4 than the high forage substrate. Methanogens were nearly washed-out with high concentrate and increased their initial numbers with high forage. The effect of dilution rate was minor in comparison to the effect of the type of substrate. Accumulation of H 2 and formate with high concentrate inhibited acetate and probably H 2 and formate production, and stimulated butyrate, rather than propionate, as an electron sink alternative to CH 4 . All three dilution rates are considered high and selected for rapidly growing bacteria. The archaeal community composition varied widely and inconsistently. Lactate accumulated with both substrates, likely favored by microbial growth kinetics rather than by H 2 accumulation thermodynamically stimulating electron disposal from NADH into pyruvate reduction. In this study, the type of substrate had a major effect on rumen fermentation largely independent of dilution rate and pH.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.
(Copyright © 2024 Ungerfeld, Cancino-Padilla, Vera-Aguilera, Scorcione, Saldivia, Lagos-Pailla, Vera, Cerda, Muñoz, Urrutia and Martínez.)
Databáze: MEDLINE
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