Enrichment of Rumen Solid-Phase Bacteria for Production of Volatile Fatty Acids by Long-Term Subculturing In Vitro

Rumen bacteria have the ability to efficiently degrade and acidify lignocellulosic biomass, among which rumen solid-phase bacteria are more dominant. However, the effectiveness of in vitro cultured ruminal solid-phase bacteria in producing volatile fatty acids (VFA) during lignocellulosic biomass degradation remains unclear. This study presents a feasibility analysis of the long-term subculture of rumen solid-phase bacteria in vitro for VFA production. The results indicated that VFA production could reach 0.20–0.30 g/g dry matter. After 40 generations (200 days) of subculturing, the bacterial community underwent alterations. The relative abundance of certain fiber-degrading, acid-producing bacteria, which were less abundant in rumen solids, such as Oribacterium and Victivallis, was significantly upregulated following subculturing in vitro. The success of this study in subculturing rumen solid-phase bacteria in vitro over an extended period and achieving efficient VFA production is of considerable importance for the practical application of rumen microorganisms in production settings.