Abstract:Abstract: [Objectives] Characteristic of energy metabolism in ruminant is negative energy balance in perinatal period. Propionic acid from ruminal microbes fermentation is a vital glyconeogenesis substrate for prevention of negative energy balance. We intend to isolate and screen a strain of Propionibacterium acnes from health cow rumen fluid, and study its rumen fermentation characteristics. [Methods] A strain of Propionibacterium acnes from rumen fluid of health cow with permanent rumen fistula under sterile condition was isolated by segregation procedure of anaerobic bacterium and specific medium SLB, and identified by extraction of the genome DNA of isolation bacterium, clone of the 16S rRNA gene, and sequencing of the strain. We study effect of the stain on pH, volatile fatty acid and lactic acid in rumen fluid by vitro and vivo test. [Results] The results showed that a strain of bacterium isolated from health cow rumen fluid was identified as the Propionibacterium acnes by morphology, biochenmical characteristics, sequence homology. In vitro test of the strain, pH in rumen fluid first dropped, to the lowest at 12 h, then increased gradually; concentration of volatile fatty acid, including acetic acid, propionic acid and butyric acid, first increased, to the highest at 12 h, then decreased gradually; the lactic acid concentration and ratio of acetate to propionate ratio decreased overall. In vivo test of the strain, pH in rumen fluid decrease overall; concentration of the volatile fatty acid increased overall. [Conclusions] A strain of Propionibacterium acnes was first isolated successfully from health cow rumen fluid at home, it is an important basis for us to develop microecological preparation for prevention of cows’ negative energy balance in perinatal period in future.
