Characteristics Of Intestinal Flora In Different Populations Of Coilia Ectenes Taihuensis In Taihu Lake

Coilia ectenes taihuensis is the dominant species of fish in Taihu Lake,intestinal flora plays an important role in its growth and reproduction.However,little is known about the relationship between intestinal flora and sex,developmental stage and geographical location of C.ectenes taihuensis in Taihu Lake.In order to study the difference of intestinal flora structure among different sexes,specifications and lake areas of Taihu Lake,in this paper,184 C.ectenes taihuensis were collected,and the V4-V5 fragments of 16 S rRNA gene were amplified by PCR.Illumina MiSeq high-throughput sequencing platform and bioinformatics software were used to explore the intestinal flora structure and potential influencing factors of C.ectenes taihuensis.The results are as follows:1.Intestinal flora structure of C.ectenes taihuensis in Taihu LakeThe intestinal flora of C.ectenes taihuensis includes 26 phyla,62 classes and 490 genera.At phylum level,Proteobacteria and Firmicutes accounted for the highest proportion?more than 85%?.Other flora with abundance more than 1% included Planctomycetes,Cyanobacteria,Tenericutes,Actinobacteria and Bacteroidetes.At the class level,gamma proteobacteria?54.25%?and Clostridia?13.60%?were the dominant bacteria,Halomonas?41.40%?dominated the genus level.The results of PICRUSt function prediction showed that genes involved in metabolism and regulation were dominant in the intestinal microbial function of C.ectenes taihuensis.The main metabolic pathways included membrane transport,amino acid metabolism,carbohydrate metabolism,energy metabolism and lipid metabolism.2.Comparison of intestinal microflora of C.ectenes taihuensis in Taihu Lake of Different SexesStatistical analysis showed that there was no significant difference in Alpha diversity index between the two sexes?P > 0.05?,while PLS-DA discriminant analysis and Lefse analysis showed that there were 20 different units in intestinal flora composition between male and female,among which Fusobacterium was higher in male and Deinococcus Thermus was relatively abundant in female.Higher degree.There was no significant difference in the function of the second metabolic pathway between male and female in the intestinal tract samples of C.ectenes taihuensis,but there were significant differences in five metabolic pathway maps in the third level,including protein digestion and absorption,sugar biosynthesis and metabolism.3.Difference of intestinal flora among different specifications of C.ectenes taihuensisThe results showed that the diversity of small size fish?S group?was higher than that of medium size fish?P group?and large size fish?L group?,while the richness of intestinal flora of large size fish was higher than that of other two groups.Beta diversity analysis also showed that group S could be separated from the other two groups.The results of flora structure analysis showed that the abundance of Proteobacteria and Tenericutes was negatively correlated with the body type of C.ectenes taihuensis,while the abundance of Firmicutes and Cyanobacteria was positively correlated with the body type of C.ectenes taihuensis.In addition,we also found that there were significant differences in the intestinal flora of different sizes of Lake squid.There were 8,10 and 4 significant differences in S,P and L groups,and 6,6 and 3 significant differences in phylum,class and genus respectively.The characteristic groups in the intestinal flora of large size of C.ectenes taihuensis mainly came from the phylum Firmicutes,with Lachnospiraceae_NK4A136_group as the dominant group.The flora of medium-sized Lake squid is mainly characterized by the Planctomycete and Thermomicrobia.The differentiated flora in the small-size Coilia ectenes taihuensis mainly belong to Proteobacteria and Tenericutes.Among them,Proteobacteria mainly belongs to Phyllobacteriaceae and Comamonadaceae,while Tenericutes mainly belongs to Mollicutes.Moreover,the functional gene abundance of intestinal growth and metabolism in large-size C.ectenes taihuensis is higher than that in small-size C.ectenes taihuensis.4.Difference of microorganism in the intestinal tract of C.ectenes taihuensis and water environment in different lake areas of Taihu lakeThe richness and diversity of intestinal flora in different lake areas were different.The richness of intestinal flora in the eastern lake area was lower than that in the other three groups,but the diversity of intestinal flora was significantly higher than that in the other three groups?P < 0.05?.The percentage of Gammaproteobacteria in intestinal samples from the eastern Lake area was 40.71%,which was much lower than that of the other three groups,while the aboundance of Alphaproteobacteria was 27.41%,which was much higher than that of the other three groups.Heatmap analysis showed that the intestinal structure of C.ectenes taihuensis in the western and southern lake areas were similar.At generic level,the dominant bacteria in the northern lake area were Halomonas?44.25%?and Ochrobactrum?11.72%?.In the western and southern lake groups,Halomonas?48.50%?and Pseudomonas?10.49%?were dominant.Microcystis was the most abundant in the southern lake area?6.02%?and in the eastern lake area?11.72%?.The dominant genera were Halomonas?27.08%?and Clostridium_sensu_stricto₁?15.63%?.In addition,Bacillus and Plesiomonas bacteria had the highest abundance in the eastern lake area.Our results also showed that the changes of some specific flora in water environment samples were consistent with those in intestinal samples,and the consistency came from the small size of C.ectenes taihuensis samples.The results of functional prediction showed that the biodegradation and metabolic abundance of isotopes in the eastern lake area were significantly lower than those in other lake areas.