Analyses of acidophilic bacterial communities and environmental changes using microcosms

1.2004年4月至2006年12月对Katanuma湖进行了调查。湖水的热模式呈二晶化。分层期4 ~ 8月，上阴离子为无硫化氢氧水，低阴离子为缺氧和硫化氢积累。在秋季循环期间，整个水柱均为氧化状态，无硫化氢。采用荧光原位杂交（FISH）技术对两种属特异性寡核苷酸探针分别测定了嗜酸杆菌属和硫杆菌属的生物量。在分层期以嗜酸菌属占优势，而在循环期两属均占优势。我们分别对分层期和环流期的湖水进行了微观观测。这些微生物在以下条件下培养；1)黑暗条件，2)…更低的温度，3)低溶解氧，4)亚铁添加，5)葡萄糖添加，6)硫代硫酸盐添加，7)控制。FISH分析表明，经硫代硫酸盐添加和低温处理1周后，酸化硫杆菌数量增加，嗜酸菌数量减少。在其他条件下的微观世界中，两属的生物量没有变化。微环境微生物群落变性梯度凝胶电泳（DGGE）分析显示，酸化硫杆菌属由At.caldus和At.caldus两种组成。嗜酸菌属主要由嗜酸菌属组成。DGGE未检出其他细菌属。虽然嗜酸菌属被认为是Katanuma湖等酸性环境的主要代表，但在秋季循环期间，在硫化物供应或低水温的条件下，Acidithiobacillus属可以增殖。少

1.The Lake Katanuma, a strongly acid lake, was surveyed during April 2004 to December 2006. The thermal pattern in the lake water showed dimictic. During the stratification period from April to August, oxic water with no hydrogen sulfide was detected in the epilimnion, whereas oxygen depletion and accumulated hydrogen sulfide were prominent in the hypolimnion. Oxic conditions and no hydrogen sulfide were observed in the entire water column during the autumn circulation period.2.Two genus specific oligonucleotide probes were used with fluorescent in situ hybridization (FISH) to measure the biomasses of the genera Acidiphilium and Acidithiobacillus, respectively. The genus Acidiphilium dominated the bacteria community at the stratification period, while both genera dominated at the circulation period.3.We made the microcosms from the lake water of the stratification and circulation periods, respectively. These microcosms were cultured under the following conditions ; 1)dark condition, 2) … More low temperature, 3)low dissolved oxygen, 4)ferrous addition, 5)glucose addition, 6)thiosulfate addition, and 7)control. FISH analysis indicated that the increased abundant of Acidithiobacillus and the decrease of Acidiphilium were observed after 1 week in the microcosms treated with the thiosulfate addition and low temperature. In the microcosms of the other conditions, the biomasses of two genera have not changed.4.Denaturing gradient gel electrophoresis (DGGE) analysis of the microbial community in the microcosms revealed that the genus Acidithiobacillus was consisting of two species, At.caldus and At.albertensis and the genus Acidiphilium was mainly composed of A.acidophilum. Other bacteria genera were not detected by DGGE. Although Acidiphilium species are considered the major representatives of the acidic environments such as the Lake Katanuma, the genus Acidithiobacillus could proliferate under the conditions of sulfide supply or low water temperature during autumn circulation period. Less