Effects of Dietary Bacillus amyloliquefaciens SCAU-070 (Based on a Woody Plant-Based Diet) on Antioxidation, Immune and Intestinal Microbiota of Tilapia (Oreochromis niloticus)

Abstract

This study aimed to explore the effects of Bacillus amyloliquefaciens (BA) as one woody forage addition (as a probiotic, 1 × 107 CFU/g) on tilapia (Oreochromis niloticus). Woody forage is one kind of fishery feed that could significantly enhance the growth, feed utilization, and digestibility of tilapia. At first, tilapia was divided into eight groups and fed with control, control + BA, Moringa oleifera, M. oleifera + BA, Neolamarckia cadamba, N. cadamba + BA, Broussonetia papyrifera, and B. papyrifera + BA diets, respectively. After dieting for 8 weeks, the intestinal morphology of tilapia in the eight groups was observed, and the effects of the B. amyloliquefaciens addition and wordy forage on the intestine functions were analyzed by two-way ANOVA. As no significant negative effects were found on the woody forage on tilapia, the villus height, density and width, and epithelial goblet cells in the posterior intestines of tilapia with BA supplementation were greater than those in the groups without BA supplementation, suggesting B. amyloliquefaciens SCAU-070 could promote the growth and development of tilapia intestinal tracts. Furthermore, it was found that B. amyloliquefaciens SCAU-070 enhanced the antioxidation capacity of tilapia posterior intestine tissue by promoting the activity of superoxide dismutase and content of malondialdehyde. In addition, the result of high-throughput sequencing (16S rDNA) showed that the beneficial bacteria Cetobacterium and Romboutsia in the probiotic groups increased significantly, while the potential pathogenic bacteria Acinetobacter decreased significantly.