Effects of microwave on the potential microbiota modulating effects of agro-industrial by-product fibers among different individuals

Microwaving was used to improve the functional properties of dietary fibers. However, the effects of microwave on the fermentability of different fibers and their role in modulating the gut microbiota were not clear. Four agro-industrial by-product fibers were treated with microwave and their fermentability and microbiota-modulating effects on different inoculum sources were investigated. The microwave treated fiber had a looser microscopic structure and more soluble dietary fiber (SDF). Microwave treatment increased soluble fiber the most, short-chain fatty acid production the most, and altered the microbial community the most in soybean fiber, while it caused the least changes in fiber structure and fermentability in sweet potato fiber. Although fecal inocula and fiber source had a greater effect on fiber fermentation, microwave treatment had a small but significant effect on fiber fermentability. Microwave treatment decreased gas production and pH in all four fibers. The key bacteria that responded to microwave treatment were clustered into 25 co-abundance groups (CAGs). CAG10 consisting of Blautia spp. and Bifidobacterium spp. was affected by microwave treatment and positively associated with SDF in all donors. This study showed that the new niches created by microwave, including increased SDF and loosened fiber structure, both contributed to the improvement of the fermentability and microbiota modulating effects of the different fibers.