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首页> 外文期刊>Archiv fur Hydrobiologie >The role of light and concentration gradients in the vertical stratification and seasonal development of phototrophic bacteria in a meromictic lake
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The role of light and concentration gradients in the vertical stratification and seasonal development of phototrophic bacteria in a meromictic lake

机译：光和浓度梯度在淡水湖泊中光养细菌的垂直分层和季节性发育中的作用

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The seasonal population dynamics of phototrophic sulphur bacteria and their vertical stratification in Lake La Cruz were studied over two consecutive summers. Development of purple sulphur bacteria occurred just below the oxic-anoxic boundary (the plate located at 14-15 m depth). The principal constituent was a species of Amoebobacter, containing okenone as its main carotenoid and which reached maximal densities at the end of summer (2.2 x 10(6) cells/ml and BChl.-a concentrations of 111 mu g/l in September 1987). Green phototrophic bacteria developed below the Amoebobacter layer at a mean depth of 16 m. Pelodicyton clathratiforme was the dominant species, reaching maximal cell concentrations of 3.1x10(6) cells/ml and BChl.-d concentrations of 362 mu g/l, also in September. Growth of these purple and green sulphur bacteria was light-limited, and sulphide was also present in very low concentrations owing to the low sulphate content of the lake. The two thermal stratification periods under study differed noticeably as a consequence of altered meteorological conditions and structural differences in the water column, with a shallower oxic-anoxic boundary and a major development of algal populations in the upper oxic layer during the second period. This reduced the light available to deep phototrophic bacteria, which were unable to attain the biomass achieved in the earlier period. The monimolimnion of Lake La Cruz acts as a refuge for phototrophic bacteria during the mixing period and this is considered to be a key factor in understanding the ecology of these microorganisms. [References: 38]
机译：拉克鲁兹湖连续两个夏季研究了光养性硫细菌的季节性种群动态及其垂直分层。紫色硫细菌的产生恰好发生在有氧-缺氧边界（板位于14-15 m深度）的下方。主要成分是一种变形杆菌，它以酮为主要类胡萝卜素，在夏季末达到最大密度（2.2 x 10（6）个细胞/ml，BChl.-1987年9月浓度为111μg/ l）。 ）。绿色的光养细菌在变形杆菌层以下平均深度为16 m处发育。 clathratiforme是最主要的物种，在9月也达到了3.1x10（6）细胞/ ml的最大细胞浓度和362μg / l的BChl.-d浓度。这些紫色和绿色硫细菌的生长受到光的限制，并且由于湖中硫酸盐含量低，硫化物也以非常低的浓度存在。由于气象条件的改变和水柱的结构差异，正在研究的两个热分层期显着不同，在第二个阶段，较高的含氧层边界有较浅的含氧-缺氧边界和藻类种群。这减少了深光养细菌的光，这些细菌无法获得早期获得的生物量。拉克鲁斯湖的单核生物在混合期间充当光养细菌的避难所，这被认为是了解这些微生物生态的关键因素。 [参考：38]

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