Study on intestinal diversity of Tilapia

Streptococcus agalactiae, as one of the common pathogens in aquaculture, severely disrupts the balance of intestinal flora and threatens fish health, which has caused the aquaculture industry heavy losses. In this study, Lactococcus lactis was used as a probiotic to explore its therapeutic effect on zebrafish infected with S. agalactiae. This study was divided into three groups: the control group (a) injected with PBS, the infected group (B) injected with S. agalactiae, and the treated group (C) injected with S. agalactiae (SA) by L. lactis KUST48 (LLK). Then, the 16S rRNA gene sequences of intestinal flora of these three groups were sequenced using Illumina high-throughput sequencing technology. The results showed that the abundance of intestinal bacteria was significantly decreased in the SA-infected group and showed a high abundance of SA, while the relative abundance of the intestinal flora was increased in the LLK-treated group with a decrease in the relative abundance of SA compared with the control group. In the statistical results of COG function classification, the abundance of each biological function in the SA-infected group was significantly lower than the abundance of each biological function of the control group and the LLK-treated group, showing that L. lactis KUST48 has a certain therapeutic effect on zebrafish infected with S. agalactiae.