| Budget Amount *help |
¥4,020,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2006: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Various colored microbial mats were observed in a slightly alkaline (pH 8.5) and sulfide-containing hot spring at Nakabusa, Japan. Dense olive-green mats developed at 65℃ in the effluent from the hot spring, while white to gray colored microbial streamers were observed at 75℃. The 16S rDNA based DGGE analysis showed the predominance of three thermophilic members of the Bacteria ; sulfur-oxidizing Aquificales spp., sulfate-reducing Thermodesulfobacterium spp. and filamentous anoxygenic photosynthetic Chloroflexus aggregans in the microbial mats at 65℃. However, photosynthetic Chloroflexus aggregans was not detected in the microbial streamer at 75℃. The results based on 16S rDNA coincided with those of the functional gene analysis using apsA for sulfate-reducing bacteria and pufLM for photosynthetic bacteria in the 65℃ microbial mat. The in vitro sulfide-monitoring experiments suggested slight sulfide generation by sulfate-reducing bacteria under anaerobic-dark conditions, sulfide utiliz
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ation by photosynthetic bacteria under anaerobic-light conditions and rapid consumption of sulfide by sulfur-oxidizing bacteria under aerobic-dark conditions. From these results, we concluded that the light-dependent microbial sulfide oxidation process was significantly involved in the sulfur cycling among sulfur-oxidizing bacteria and sulfate-reducing bacteria, in the microbial mats at 65℃. On the other hand, to obtain amino acid-utilizing sulfate reducers enrichment culture was carried out with a medium containing Casamino acids and sulfate, and inoculated in coastal marine sediment of eutrophic Tokyo Bay. A sulfate reducer, strain C/L2T, was isolated from the sulfide-producing enrichment culture after further enrichment with lactate and sulfate by the agar shake dilution method. Cells of strain C/L2T were vibrio-shaped, Gram-negative and motile rods (0.7-1.0 um wide x 1.0- 3.5 um long) with single polar flagella. Strain C/L2T was proposed as a new species in this genus, with the name of Desulfovibrio marinisediminis, sp. nov. because of its physiological and phylogenetic differences from Desulfovibrio acrylicus. Less
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