Effects of fecal bacteria on growth, digestive capacity, antioxidant capacity, intestinal health of large yellow croaker (Larimichthys crocea) larvae

Marine fish at early life is vulnerable to the threat of external pathogenic bacteria with unestablished intestinal flora. Early life intervention could contribute to healthy development of larvae gut tract. Consequently, the present study examined how large yellow croaker larvae (Larimichthys crocea) (mean body weight 3.64 +/- 0.20 mg) responde to fecal microbiota came from 12-month-old large yellow croaker by oral administration. The intestinal contents of the donor were prepared into bacterial solution and sprayed on the Micro-diet. After 30 days feeding, growth performance, intestinal development, digestive ability and gut microbiota of larvae were detected. Results showed that there was no significant difference in survival rate. After fecal microbiota trans-plantation (FMT) treatment fish larvae had significantly higher final body weight, weight gain rate and specific growth rate. FMT treatment remarkably enhanced the activities of alpha-amylase and trypsin in intestinal segment and the activity of lipase and trypsin in pancreatic segment. Furthermore, FMT treatment significantly increased the activity of leucine-aminopeptidase on brush border membrane and the mRNA expression of pcna and occludin compared with the control group. Similarly, gut in larvae of FMT group had significantly higher villus height and muscular thickness. Moreover, FMT treatment significantly improved the activity of lysozyme and decreased malondialdehyde concentration in visceral mass. FMT treatment increased intestinal microbial diversities and altered intestinal microbiota profile of larvae. Spearman analysis revealed that FMT profoundly influenced the function of gut microbiota. Bacteria introduced by FMT may play a role in digestion and intestinal tract development. In conclusion, our results revealed that FMT treatment improved microbial diversity and modu-lated intestinal microecology of large yellow coraker larvae, which could significantly affect the digestive ca-pacity, antioxidant capacity, intestinal development and intestinal health, thus improved its growth performance.