太湖人工生态系统中氮循环细菌分布

对太湖五里湖的以水生高等植物为主的湖泊人工生态系统，用最大可能数法，测定了该系统内各种生态类型水生高等植物群落内的４类氮循环细菌的分布。结果表明反硝化细菌的最大可能数，在水生高等植物群落内水体中较敞水区湖水高２－５个数量级差异极显著；漂服植物各落内水体的反硝化细菌ＭＰＮ值较沉水和浮叶植物群落内水体高２－３个数量级，差异极显著；

Distribution of Nitrogen Cycle Bacteria in an Artificial Ecosystem of Taihu Lake

This paper first report the distribution and role of four nitrogen cycle bacteria in the artificial ecosystem of Taihu Lake. These nitrogen cycle bacteria include ammonifying bacteria, denitrify-ing bacteria, nitrobacteria and nitrovsobacteria, determined with MPN method. 1 he MPN values of denitrifying bacteria in the water covered by Alternanthera philoxeroides and Eichhornia cras-sipes are about 2-3 and 2-5 oraer-of-magnitudes higher than the water vegetated with other macrophytes and unvegetated water respectively. There is significant difference between them (P <0.01). The MPN values of ammonifying bacteria in vegetated water are markedly higher than that in unvegetated water. The MPN values of nitrosobacteria in vegetated water are notably higher than those in unvegetated water (P<0.01). The MPN values of nitrobacteria and ni-trosobacteria in the water vegetated with submerged plant are nigher than those in the water cov-ered by floating plant. The MPN values of ammonifying and denitrifying bacateria, nitrosobacte-ria are very dense in rhizosphere, and decrease from rhizosphere to outside.