人工湿地不同季节与单元之间根际微生物多样性

采用选择性平板培养基法和PCR-DGGE法比较研究了三级垂直潜流人工湿地污水处理系统中不同季节与单元之间根际微生物数量与多样性,结果表明,随着“秋-冬-春-夏”的季节的变化,2种方法测定的微生物数量都呈现“高-低-高”季节性变化现象,但选择性平板培养基法显示秋季数量最多,PCR-DGGE法显示夏季数量最多.从三级处理单元的1-3级,两种方法测定的微生物数量都呈现“低-高-低”的规律.除土样11外,其余相同季节的土样均出现聚集在同一个分支下.得到的4个差异序列(YP1-YP 4),经BLAST比较,分别找到同源性最近的已知类群,分别为肠杆菌属、弧菌、欧文氏菌、产酸克雷伯菌.BLASTX比较发现YP1与细菌代谢分解有机物有关;YP2蜡样芽胞杆菌生命活动相关,具有解磷的作用;YP3与APOE载脂蛋白e功能相似,参与细菌的分解代谢;YP4功能可能与细菌去氮有关.

Seasonal changes in microbial diversity in different cells of a wetland system constructed for municipal sewage treatment

Selective plating medium and PCR-DGGE techniques were applied to analyze the seasonal changes in the number and diversity of micro-organisms in the rhizosphere of three sequenced cells in a vertical subsurface-flow wetland system constructed for municipal sewage treatment. The relationship between the community structures of the microorganisms and their functions in removal of the organic pollutants was also analyzed. The results obtained from the two applied methods showed that with the seasonal changes in the sequence of autumn-winter-spring-summer, the number of the micro-organisms displayed a general "up-down-up" pattern. The largest number of microorganisms from the rhizoshpere in three treatment cells detected by the selective plating medium method was in the autumn while that by the PCR-DGGE techniques was in the summer. Correlation analysis indicated that the seasonal change in temperature was the main factor that determined the observed pattern by affecting the growth of the microorganisms. In a given season, the number of micro-organisms obtained from the two applied methods displayed a different pattern in the three sequenced treatment cells. Towards the flow direction in the sewage treatment process, the number of micro-organisms increased from the first cell to the second cell and then decreased in the third cell, accordingly, with most of the organic pollutants being removed in the first two treatment cells. Based on the structure comparability of the microbial community among treatment cells, all soil samples collected in the same season, except for sample no. 11, were clustered in the same branch, with all DGGE comparability values being higher than 20%, which can thus be classified into the same group. The DGGE spectrograms of the soil microorganisms from different seasons are different. The highest comparability value, 40%, was found in the spring, while the lowest, about 25%, was in the summer, indicating that the level of the microbial diversity was higher in the summer season under the tested conditions. Four different sequences(YP1-YP 4)were obtained, and their closest known-origin groups were identified by BLASTX analysis as Enterobacter sp., Vibrio sp., Erwinia sp. and Klebsiella oxytoca, respectively. The BLASTX comparison tests showed that YP1 played an important role in decomposing organic matters; YP2 was fund to be related to the life activities of the Cerea Spore Bacilli with functions in phosphate dissolution; YP3 had functions similar to the apolipoprotein e (APOE) that involved in catabolism and metabolism of micro-organisms; and YP4 had an effect on nitrogen removal subject to microbial activities.