Open AccessInvolvement of recently cultured group U 2 bacterium in ruminal fiber digestion revealed by coculture with F ibrobacter succinogenes S 85
Author(s) -
Fukuma Naoki,
Koike Satoshi,
Kobayashi Yasuo
Publication year - 2012
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2012.02649.x
Subject(s) - fibrobacter succinogenes , biology , rumen , food science , strain (injury) , straw , bacteria , monoculture , propionate , digestion (alchemy) , microbiology and biotechnology , fermentation , biochemistry , agronomy , chemistry , chromatography , genetics , anatomy
In a previous study, we reported the ecological significance of uncultured bacterial group U 2 in the rumen. In this study, the involvement of a recently cultured group U 2 bacterium, strain R ‐25, in fiber digestion was tested in coculture with the fibrolytic bacterium F ibrobacter succinogenes S 85. Dry matter ( DM ) digestion, growth and metabolites were examined in culture using rice straw as the carbon source. Although strain R ‐25 did not digest rice straw in monoculture, coculture of strain R ‐25 and F . succinogenes S 85 showed enhanced DM digestion compared with that for F . succinogenes S 85 monoculture (36.9 ± 0.6% vs. 32.8 ± 1.3%, P < 0.05). Growth of strain R ‐25 and production of the main metabolites, d ‐lactate (strain R ‐25) and succinate ( F . succinogenes S 85), were enhanced in the coculture. Enzyme assay showed increased activities of carboxymethylcellulase and xylanase in coculture of strain R ‐25 and F . succinogenes S 85. Triculture including strain R ‐25, F . succinogenes S 85 and Selenomonas ruminantium S 137 showed a further increase in DM digestion (41.8 ± 0.8%, P < 0.05) with a concomitant increase in propionate, produced from the conversion of d ‐lactate and succinate. These results suggest that the positive interaction between strains R ‐25 and F . succinogenes S 85 causes increased rice straw digestion.