Institute of Ecology and Genetics, University of Aarhus, Ny Munkegade, DK-8000, Aarhus C, Denmark.
Microb Ecol. 1988 Sep;16(2):133-47. doi: 10.1007/BF02018909.
The zonation and structure of phototrophic microbial mats were studied along two thermal gradients in sulfide-rich hot springs of southwest Iceland. The green, filamentous bacteriumChloroflexus and the unicellular, "high-temperature form" (HTF) ofMastigocladus formed mats growing up to a temperature limit of 62-66°C. The dominant phototrophs wereChloroflexus sp.,Mastigocladus laminosus, andPhormidium laminosum, respectively, at the three temperature intervals: >60°C, 60°C to 55-50°C, and <55-50°C. AChloroflexus mat growing at 60°C under 60μM H2S was anoxic in the light with the exception of a 0.5 mm thick band of HTFMastigocladus which produced oxygen. The oxygenic photosynthesis of these H2S-sensitive cyanobacteria was probably dependent on a preceding sulfide depletion by the anoxygenicChloroflexus. Measurements of spectral radiance gradients with a fiberoptic microprobe showed maximum light attenuation by carotenoids and bacteriochlorophyllC. AM. laminosus mat growing at 52°C was oxic throughout and showed maximum light attenuation by carotenoids, chlorophyllA, and phycocyanin, but no detectable phycoerythrocyanin absorption.
本研究在冰岛西南部富硫热泉中沿两条温度梯度对光养微生物席的分带和结构进行了研究。绿色丝状细菌绿屈挠菌和单细胞的“高温型”（HTF）巨枝藻形成了席状生物，其生长温度上限可达 62-66°C。在三个温度区间（>60°C、60°C 至 55-50°C 和 <55-50°C），优势光养生物分别为绿屈挠菌、层状巨枝藻和厚壁磷杆藻。在 60°C、60μM H2S 条件下生长的绿屈挠菌席在光照下处于缺氧状态，只有 0.5 毫米厚的 HTF 巨枝藻层产生氧气。这些对 H2S 敏感的蓝细菌的产氧光合作用可能依赖于先前由厌氧绿屈挠菌进行的硫化物耗尽。利用光纤微探针测量光谱辐射梯度表明，类胡萝卜素和菌叶绿素 C 对光的衰减最大。在 52°C 下生长的 AM. laminosus 席始终处于好氧状态，其光衰减最大的是类胡萝卜素、叶绿素 A 和藻蓝蛋白，但未检测到藻红蛋白的吸收。
