Chemical cycle and strategy for starvation of photosynthetic bacteria in soil and water

在日本Nakabusa的微碱性（pH 8.5）和含硫化物的温泉中观察到各种颜色的微生物垫。温泉出水在65℃时形成密集的橄榄绿色菌垫，而在75℃时观察到白色至灰色的微生物条带。基于16 S rDNA的DGGE分析显示细菌的三个嗜热成员占优势：硫氧化Aquificales spp.，硫酸盐还原嗜热假单胞菌在65℃时，微生物垫中有丝状无氧光合绿弯藻聚集体。而在75℃时，微生物流中没有检测到光合聚团绿弯藻。基于16 SrDNA的结果与65℃微生物垫中硫酸盐还原菌apsA和光合细菌pufLM的功能基因分析结果一致。体外硫化物监测实验表明，在厌氧黑暗条件下，硫酸盐还原菌产生轻微的硫化物，硫化物利用率为100%。 ...更多信息 光合细菌在厌氧光照条件下快速消耗硫化物，硫氧化细菌在有氧黑暗条件下快速消耗硫化物。结果表明，65℃下微生物垫中硫氧化菌和硫酸盐还原菌之间的硫循环主要是光依赖型微生物硫化物氧化过程。另一方面，为了获得利用氨基酸的硫酸盐还原剂，用含有酪蛋白氨基酸和硫酸盐的培养基进行富集培养，并接种在富营养化的东京湾的沿海海洋沉积物中。采用琼脂摇瓶稀释法，对产硫菌进行乳酸盐和硫酸盐的富集培养，得到一株硫酸盐还原菌C/L2 T。菌株C/L2 T的细胞为弧菌形、革兰氏阴性和活动杆（0.7-1.0 μ m宽X 1.0- 3.5 μ m长），具有单极鞭毛。由于C/L2 T菌株与丙烯脱硫弧菌（Desulfovibrio acrylicus）的生理特性和系统发育上的差异，将其命名为海洋脱硫弧菌（Desulfovibrio marinisediminis，sp. nov.）。少

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 … More 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