草鱼养殖池塘蓝藻暴发时水体细菌群落特征分析

为了解蓝藻暴发池塘中细菌群落特征,采集3个地区(广东、云南、贵州)4个淡水养殖场的蓝藻暴发池塘和非蓝藻暴发池塘(对照池塘)水样,并检测其理化因子及生物指标,采用PCR-DGGE技术分析其细菌群落结构差异。依据PCR-DGGE指纹谱带的丰度对养殖水体细菌群落多样性进行了分析,并对水体细菌群落结构进行了UPGMA聚类分析。结果发现:蓝藻暴发池塘水体的PO_4-P含量均显著高于对照池塘(P0.01);线性回归分析表明,PO_4-P与代表蓝藻暴发程度的叶绿素a存在正相关关系(R~2=0.869,P0.01);而且理化因子与细菌群落的RDA分析表明,PO_4-P与蓝藻暴发池塘细菌群落关系密切。蓝藻暴发池塘与对照池塘水体的细菌群落结构间存在显著差异;进一步测序分析显示,蓝藻暴发池塘特定的细菌为Flexibacter,其可能对蓝藻有裂解作用;而Synechococcsus在蓝藻暴发池塘的含量明显低于对照池塘,可能是Microcystis的大量暴发抑制了Synechococcsus的生长。

Characteristics of bacterial community of the grass carp pond when cyanobacterial blooming occurred

In order to reveal the characteristics of bacterial community in the cyanobacterial blooming pond, the water samples in the cyanobacterial blooming ponds and the control ponds were collected from four aquaculture farms located in Guangdong, Yunnan and Guizhou Provinces, respectively. Both the physicochemical factors and biological indicators were analyzed. By applying polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique,the differences in bacterial community structure in these water bodies were found. The bacterial community diversity in aquaculture water were analyzed according to the abundance of PCR-DGGE fingerprint bands, and conducted an unweighted pair group method with arithmetic mean (UPGMA) cluster analysis on the bacterial community structure in the water body. The results indicated that the PO₄-P content was significantly higher in cyanobacterial blooming pond than that in the control pond (P<0.01).Linear regression analysis revealed a positive correlation between PO₄-P and the content of chlorophyll a (Chl.a), which represents the degree of cyanobacterial blooming (R²=0.869, P<0.01).The analysis of physicochemical factors in combination with the redundancy analysis (RDA) in bacterial community indicated a close relationship between PO₄-P and bacterial community in aquaculture water. While no significant difference in bacterial community diversity was seen between cyanobacterial blooming pond and control pond (P>0.05), significant differences in bacterial community structure between the two ponds existed. Further sequencing analysis revealed that the characteristic bacteria in the cyanobacterial blooming pond was Flexibacter, which might play a role in algal pyrolysis. The Synechococcsus content was significantly lower in the cyanobacterial blooming pond than that in the control pond. This reduced Synechococcsus content might be related to the inhibition of Synechococcsus growth by the substantial blooming of Microcystis.