庙湖水华过程中浮游细菌丰度与多样性的变化

藻类的过度繁盛(水华)将产生大量有机质,并由此造成严重危害,而浮游细菌在有机质分解过程中的作用尚未得到充分研究。描述了2010年4-8月武汉庙湖叶绿素与不同形态氮和磷的浓度,分析了不同形态细菌的丰度和多样性(以DNA的DGGE图谱为表征)及其与胞外水解酶活性的关系。结果表明,庙湖叶绿素a与总磷浓度显著正相关(P<0.05),4月与7月的叶绿素浓度均超过120μg/L。在水华间隔期内,自由生活菌的数量大幅度升高(1.39×106～2.72×107个/mL),而附着细菌的数量则大体相近(7.77×105～4.49×106个/mL)。水华衰亡初期,二者的群落结构基本相似,并随时间逐渐分化至显著不同的程度;附着细菌的数量直接或间接地明显正比于胞外水解酶活性,在水华有机碎屑分解过程中的作用更为重要。

Variations in Abundance and Diversity of Bacterioplankton in the Process of Algal Blooms in Lake Miaohu

Algae over-prosperous(algal blooms) will produce a lot of organic matter and result serious harm,but the role of bacterioplankton in the process of decomposition of organic matter has not yet been sufficiently studied.In the present study,chlorophyll a,different forms of nitrogen and phosphorus concentration distribution in Lake Miaohu were investigated systematically from April to August in 2010.The different forms of bacterial abundance and diversity(for the characterization of the DGGE profiles of DNA) as well as its relationships with activities of extracellular hydrolytic enzymes were also analyzed.The results showed chlorophyll a and total phosphorus concentrations had a highly significant positive correlation in Lake Miaohu,meanwhile chlorophyll a concentrations exceeded 120 μg /L in April and July.During the interval of algal blooms,the abundance of free-living bacteria significantly increased(1.39 × 106-2.72 × 107 ind./mL),whereas attached bacteria kept their quantities in a certain level(7.77 × 105-4.49 × 106 ind./mL).In the early stage of water bloom declines,free-living bacteria and attached bacteria had similar community structure;somehow the differentiation between their community structures gradually came to a significantly varying degree over time.In addition,the abundance of attached bacteria had positive significant correlation directly or indirectly with the activities of extracellular hydrolytic enzymes,therefore,attached bacteria have a more important role in the decomposition of organic detritus from algal blooms.