Microbiome

Isolation and genome characterization of a poly(3-hydroxybutyrate)-producing Brevibacillus sp. from rumen fluid of dairy cows

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Abstract

The rumen microbiome contributes to key dairy cattle phenotypes, including feed efficiency and methane emission, yet gene-level microbial traits that support adaptation to host-linked rumen conditions remain poorly defined. Poly(3-hydroxybutyrate) (PHB) is an intracellular storage polyester that buffers carbon flux and redox balance during nutrient transitions. To define a PHB-associated adaptive trait in the rumen, a PHB-accumulating bacterium was isolated from Holstein rumen fluid and its genomic basis was examined. Brevibacillus sp. SLAM10 showed strong intracellular Nile Red-positive inclusions, and the extracted polymer matched a commercial PHB standard by FT-IR, with a Pearson correlation coefficient greater than 0.99. Growth-phase imaging showed sparse fluorescence at 24 h, broader cytoplasmic signal with strong cell-to-cell variation at 48 h, and fewer, larger localized granules at 72 h, placing PHB accumulation in late stationary phase. Genome analysis identified multiple PHB-linked genes and a Class IV-like PHB locus containing phaR and phaQ, with a fabG homolog in the canonical phaB position. SLAM10 PhaC showed 51.9% and 48.4% amino acid identity to reference Class IV PHA synthases, and the phaB-position fabG copy showed the highest similarity to reference PhaB proteins. This work defines the timing and genomic organization of PHB-associated storage metabolism in a Holstein rumen isolate and provides a gene- and pathway-level framework for future analysis of host-linked rumen microbial function in dairy cattle.

Keywords: 2026

How to Cite:

Kim, A., Kang, M., Kim, M., Jang, K. & Kim, Y., (2026) “Isolation and genome characterization of a poly(3-hydroxybutyrate)-producing Brevibacillus sp. from rumen fluid of dairy cows”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2293947. doi: https://doi.org/10.31274/wcgalp.24316

Rights: 1