Polysaccharides from fermented wheat bran enhanced the growth performance of zebrafish (Danio rerio) through improving gut microflora and antioxidant status

This study explored the potential effects of dietary wheat bran polysaccharides (WBP) or fermented wheat bran polysaccharides (FWBP) supplementation on growth performance, antioxidant status, and gut microbiota of zebrafish. An 8-week feeding trial was conducted using the basal diet (control) complemented with 1% WBP or FWBP. The results showed that FWBP significantly enhanced specific growth rate (SGR) and reduced feed conversion ratio (FCR) of zebrafish in comparison with control. The mRNA expression of antioxidant-related genes (CAT, GPX-3 and GST), Nrf2, and P38 were significantly upregulated in FWBP group. Additionally, WBP upregulated the mRNA expression of GPX-3. Regarding the gut microbiota, Illumina sequencing analysis revealed that the Simpson index was notably increased in FWBP group. Moreover, FWBP increased the relative abundance of Firmicutes and decreased the relative abundance of Aeromonas. Compared to WBP group, the growth performance, mRNA expression of CAT, GST, Nrf2, and P38, as well as the relative abundance of Firmicutes were higher in FWBP group, while the relative abundance of Aeromonas was lower. Hence, the present study indicates that FWBP displayed superior potential as a growth-promoter by positively regulating gut antioxidant-associated gene expression and gut microbiota in zebrafish.