Bacterial Community Composition Associated with Freshwater Cyanobacterial Blooms of Intensive Culture Ponds

To determine the composition of the bacterial communities associated with cyanobacteria in the freshwater ponds of Channa argus in intensive culture in the late culture period, we examined the bacterial community of non-cyanobacterial blooms freshwater ponds (C) and cyanobacterial blooms freshwater ponds (CB) using PCR-denaturing gradient gel electrophoresis (PCR-DGGE) and 16S rDNA clone library. DGGE profiles showed that Microcystis sp. (JX391871.1), Leptospira sp. (JX067673.1) and Verrucomicrobium sp. (FN668203.2) existed only in CB, whereas Sphingomonas sp. (AB681542.1) and Paenibacillus sp. (JQ659563.1) were the C-specific bacteria. The 16S rDNA clone libraries of pond water showed that Actinobacteria (15 OTUs, 31.9%), Bacteroidetes (13 OTUs, 28.7%), Fibrobacteres (7 OTUs, 14.9%) and Proteobacteria (5 OTUs, 10.0%) were the dominant groups in C; the four dominant groups in CB were Bacteroidetes (17 OTUs, 34.7%), Actinobacteria (9 OTUs, 18.4%), Fibrobacteres (6 OTUs, 12.2%) and Proteobacteria (8 OTUs, 16.2%). In the clone library, distribution of sequences belonging to Fibrobacter in CB (22.2% of the 99 clones) was twice as that of C (11.1% of the 99 clones). In both DGGE map and 16S rDNA clone library the Firmicutes group (JQ659563.1 in DGGE and 3 OTUs in C library) existed only in C. These results suggested that the composition of bacterial communities changed with the cyanobacterial blooms in Channa argus intensive culture freshwater ponds, and whether the change of the Firmicutes-to-Bacteroidetes ratio could be used to predict cyanobacterial blooms in these types of ponds required further validation.