| Budget Amount *help |
¥7,100,000 (Direct Cost: ¥7,100,000)
Fiscal Year 2000: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1999: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1998: ¥3,200,000 (Direct Cost: ¥3,200,000)
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| Research Abstract |
The thermostable-tryptophanase producing microbe, Symbiobacterium thermophilum (ST) is a themophilic symbiotic bacterium which growth in the coculture with thermophilic Bacillus strain S (BS). In the present study, we elucidated following ; (1) as for the growth factor for ST (GF), we first established quantitative PCR procedure, which enabled specific quantification of ST.By the precise analyses based on the technique, we revealed that GF is a general metabolite existing in the culture supernatant not only of BS but of all the other bacteria tested. Dialyzing culture separating ST and BS enabled pure growth of ST, thus it was suggested that a small dialyzable molecule is responsible for the GF activity. Attempt to purify the low molecular weight substance led us to find that the GF activity is present in vapor fraction. BS culture supernatant also contained a high-molecular weight substance carrying the GF activity, which was assumed to be involved in the production of the GF of low-molecular mass.
Second, we performed phylogenetic analysis based on the 16S rDNA sequence and revealed that ST belongs to a novel branch created at the outermost position in the Gram-positive bacterial group, which did not cluster to any other bacterial group hitherto known.
Third, we examined environmental distribution of ST and its related organisms, and found that these bacteria are quite general, distributing not only in soil environment mainly including compost, but also in digestive organs of animals. Feeds for animals also frequently carried the bacteria. 16S rDNA-based phylogeny of the isolates showed that those fell into the novel branch created by ST at the outermost position in Gram-positive group, and further diversity forming new branches in the cluster. Furthermore, the DGGE analysis of the newly obtained 16S rDNA fragments implied the presence of multiple species belonging to Symbiobacterium.
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