The effect of resistant starch (RS) on the bovine rumen microflora and isolation of RS-degrading bacteria
Resistant starch (RS) in the diet reaches the large intestine without degradation, where it is decomposed by the commensal microbiota. The fermentation of RS produces secondary metabolites including short-chain fatty acids (SCFAs), which have been linked to a variety of physiological and health effects. Therefore, the availability of RS as a prebiotic is a current issue. The objectives of this study were (1) to use metagenomics to observe microbial flora changes in Bos taurus coreanae rumen fluid in the presence of RS and (2) to isolate RS-degrading microorganisms. The major microbial genus in a general rumen fluid was Succiniclasticum sp., whereas Streptococcus sp. immediately predominated after the addition of RS into the culture medium and was then drastically replaced by Lactobacillus sp. The presence of Bifidobacterium sp. was also observed continuously. Several microorganisms with high RS granule-degrading activity were identified and isolated, including B. choerinum FMB-1 and B. pseudolongum FMB-2. B. choerinum FMB-1 showed the highest RS-hydrolyzing activity and degraded almost 60% of all substrates tested. Coculture experiments demonstrated that Lactobacillus brevis ATCC 14869, which was isolated from human feces, could grow using reducing sugars generated from RS by B. choerinum FMB-1. These results suggest that Bifidobacterium spp., especially B. choerinum FMB-1, are the putative primary degrader of RS in rumen microbial flora and could be further studied as probiotic candidates.
KeywordsBovine rumen Granular starch-degrading bacteria Resistant starch Bifidobacterium
This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (no. 2017R1A2B4004218). Additionally, this research was partly supported by Main Research Programs (grant number E0170602-02) of the Korea Food Research Institute funded by the Ministry of Science and ICT.
Compliance with ethical standards
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.
Conflict of interest
The authors declare that they have no conflict of interest.
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