Microbial-feeding interactions reveal the effects of feeding blood on the gut microbiota of the aquaculture leech (Hirudo nipponica)

Leeches (Hirudo nipponica), as a kind of aquatic animal, mainly feed on fresh blood. After feeding, they needed to digest for a long time because the intestinal digestive enzyme content is low, so their digestive needed the help of gut microbiota. Here, we examined intestinal microbiota in captive Hirudo nipponica of different periods after feeding blood with high-throughput sequencing. The results showed that gut microbial diversity was lower before feeding than after. At the level of the core phylum of the gut microbiota of Hirudo nipponica, the focus was on Proteobacteria, Bacteroidetes, and Firmicutes. After feeding blood, the relative abundance of Proteobacteria decreased, while the opposite was true for Bacteroidetes and Firmicutes. The core bacteria at the genus level are Aeromonas and Mucinivorans. The results show that the structure of the gut microbiota and function are closely associated with the blood feeding. The study aimed to lay a theoretical foundation for the blood-digestive mechanism of Hirudo nipponica.