Relationship Among Water, Sediment and Intestinal Microbial Community Structure between Breeding Group and Control Group of Juvenile Huanghe Carp New Strain

A total of 1500 fish species in the Yellow River carp breeding group and the control group were reared in the pond and fed with commercial bait three times a day. In the first 2 months of feeding, samples were taken at 4 time points to measure water quality parameters. At the fourth time point, intestinal samples were taken for DNA extraction and purification. PCR amplification, purification and 16S amplicon sequencing were performed. The results showed that except for NO2-N, NO3-N and transparency, the other 11 water quality indexes were closely related to water quality bacterial community. A total of 1,364,230 original tags were obtained for 50 samples including water, sediment and intestines, with an average of 56, 842.9 tags per sample. Finally, 5105 operational taxa (OTUs) were isolated from all samples. OTU mean abundance was highest in water (1228.08±155.87). It was lowest in intestinal tract (717.50±95.31). The Alpha diversity in breeding group was higher than that in control group. There was a clear dividing line between the control group and the selective group. The intestinal microbes first clustered with the water quality microbes, and then clustered with the sediment microbial community. From the perspective of bacterial community structure, whether in the control group or the breeding group, Needle-shaped bacteria were dominant at the 2nd, 3rd and 4th time points of water samples, while Limnohabitans were dominant at the 1st time point. Rhodobacter was dominant in the intestinal tract of both the breeding group and the control group, while Firmicutes were dominant in the bottom mud. The bacteria ranked second and third at the first time point in the water were consistent with those in the bottom mud. In the intestinal tract, the abundance of Chlorooscilla and Firmicutes was different in the breeding group. These results indicated that the breeding group of new strain of Yellow River carp had specific microflora structure.