Antioxidant capacity of wheat bran fermented with gut indigenous Bifidobacterium and its antagonistic effect on food-related pathogens in vitro

Abstract

Wheat bran (WB) has several health-promoting effects. This study aimed to identify gut bacteria that increase after WB consumption and assess their functionality. Human stool samples obtained from healthy volunteers were inoculated into culture broth with or without 2% (w/v) WB and incubated under anaerobic conditions for 24 h. The microbiota in the cultures was analysed using 16S rRNA (V4) gene amplicon sequencing. The addition of WB decreased the pH from 6.9 to 5.9 (p < 0.05) and increased the acetate level by 1.6 times. Although the microbiota differed across individuals, butyrate-producing genera (Faecalibacterium and Roseburia), Blautia, and Bifidobacterium spp. were abundant in cultures supplemented with WB. Bifidobacterium pseudocatenulatum and B. adolescentis, isolated as WB-responsible gut indigenous bacteria (WB-RIBs), were found to ferment WB. The WB-RIBs increased the 1,1-diphenyl-picrylhydrazyl and superoxide anion radical-scavenging capacities of WB-supplemented cultures. Further, these WB-RIBs suppressed the growth of Salmonella Typhimurium, Staphylococcus aureus, and Bacillus cereus in WB-supplemented brain heart infusion broth. These results suggest that compounds present in WB, along with WB-RIBs, affect the gut environment. Further studies should be conducted to elucidate the mechanisms underlying the interactions between WB and WB-RIBs.