蓝藻水华形成过程对氮磷转化功能细菌群的影响

为探寻蓝藻水华形成过程中细菌群落结构和氮、磷转化功能菌群的动态变化,利用细菌16S rRNA基因的高通量测序和功能基因的荧光定量PCR(qPCR)方法,分析了在蓝藻水华过程中水体细菌群落组成及功能菌群的变化情况.高通量测序结果证明了蓝藻水华形成过程中细菌群落的多样性降低,细菌群落在水华期和非水华期具有不同的结构.随着水华过程中蓝藻密度的增加,水体中Actinobacteria和Bacteroidetes相对丰度减少,而Firmicutes相对丰度增加;蓝藻水华对聚磷菌(PAOs)具有富集作用,对硝化细菌具有抑制作用,而反硝化细菌的数量在中度水华条件下显著增加. qPCR结果显示,随着蓝藻水华的持续发展,硝化和反硝化功能基因丰度下降甚至消失,表明水体中氮转化过程可能受到抑制,此过程也有利于水华过程中微囊藻快速增殖对氮的需求,对水华蓝藻的生长具有正反馈作用.

Dynamic Changes of Nitrogen-Transforming and Phosphorus-Accumulating Bacteria Along with the Formation of Cyanobacterial Blooms

In order to reveal the dynamic changes of nitrogen-transforming and phosphorus-accumulating bacteria in the process of cyanobacterial bloom formation, bacterial community structure and functional genes associated with nitrogen cycling were analyzed using high-throughput sequencing and real-time quantitative PCR (qPCR). The high-throughput sequencing results showed that the diversity of bacterial communities decreased during cyanobacterial blooms, and the lacustrine free-living and bloom-attached bacterial communities varied with increased bloom density. With increasing density of cyanobacteria, the relative abundance of Actinobacteria and Bacteroidetes decreased, whereas that of Firmicutes increased. Moreover, the growth of phosphate-accumulating organisms was increased in the phycosphere of cyanobacterial blooms, while that of nitrifiers was inhibited. Denitrifiers increased significantly under moderate blooms. The qPCR data also revealed that the abundance of nitrification and denitrification genes decreased or disappeared with the development of cyanobacterial blooms, indicating that the nitrogen transformation process might be inhibited, which showed a positive feedback of bacterial community to the development of Microcystis blooms by satisfying the needs of the nutrients budget.