| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Research Abstract |
The present study is to explore ecology and function of uncultivated rumen bacteria through molecular biological techniques. By comparative 16SrDNA sequencing analysis of fiber-associated bacteria (bacteria tightly adherent to rice straw stems), the following results were obtained.
1.So far uncharacterized rumen bacteria were found and mainly grouped into 3 clusters (U1 through U3). U1 was in PFB phylum comprising bacteria closely related to Bacteroides, while U2 was the group close to the wood fiber digesting bacterium Clostridium aldrichii. U3 had the hemicellulolytic rumen bacterium Eubacterium ruminantium as a closest relative.
2.PCR primers specific to U2 and U3 were designed for developing real-time PCR assays to quantitate these groups. The developed assays were highly sensitive, reliable in reproducibility, and allowed rapid monitoring of each bacterial group. Such reliable assays were established for total 14 bacterial species or groups that were associated with ruminally incubated straw stems.
3.Of tightly adherent bacteria, Fibrobacter succinogenes, a potent fibrolytic species, was major in its biomass followed by U2. Also, U2 showed time-course on stems just as F.succinogenes. These results strongly suggest significant contribution of U2 to rumen fiber digestion.
4.Since many Clostridium-like bacteria with protuberance structure were observed on stems under scanning electronic microscopy, these might be U2 bacteria. Therefore, U2 could be enriched on straw sterns and isolated by using heat treatment to inoculum before cultivation.
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