Using Structural Equation Modeling to Understand Interactions Between Bacterial and Archaeal Populations and Volatile Fatty Acid Proportions in the Rumen

Veronica Kaplan-Shabtai, Nagaraju Indugu, Meagan Leslie Hennessy, Bonnie Vecchiarelli, Joseph Samuel Bender, Darko Stefanovski, Camila Flavia De Assis Lage, Susanna Elisabeth Räisänen, Audino Melgar, Krum Nedelkov, Molly Elizabeth Fetter, Andrea Fernandez, Addison Spitzer, Alexander Nikolov Hristov, Dipti Wilhelmina Pitta

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Microbial syntrophy (obligate metabolic mutualism) is the hallmark of energy-constrained anaerobic microbial ecosystems. For example, methanogenic archaea and fermenting bacteria coexist by interspecies hydrogen transfer in the complex microbial ecosystem in the foregut of ruminants; however, these synergistic interactions between different microbes in the rumen are seldom investigated. We hypothesized that certain bacteria and archaea interact and form specific microbial cohorts in the rumen. To this end, we examined the total (DNA-based) and potentially metabolically active (cDNA-based) bacterial and archaeal communities in rumen samples of dairy cows collected at different times in a 24 h period. Notably, we found the presence of distinct bacterial and archaeal networks showing potential metabolic interactions that were correlated with molar proportions of specific volatile fatty acids (VFAs). We employed hypothesis-driven structural equation modeling to test the significance of and to quantify the extent of these relationships between bacteria-archaea-VFAs in the rumen. Furthermore, we demonstrated that these distinct microbial networks were host-specific and differed between cows indicating a natural variation in specific microbial networks in the rumen of dairy cows. This study provides new insights on potential microbial metabolic interactions in anoxic environments that have broader applications in methane mitigation, energy conservation, and agricultural production.

Original languageEnglish (US)
Article number611951
JournalFrontiers in Microbiology
StatePublished - Jun 9 2021

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Microbiology (medical)

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