Modulation of gut microbiota in rats fed high-fat diets by processing whole-grain barley to barley malt

Scope: The gut microbiota is linked with human health, and by manipulating its composition, health conditions might be improved. The aim of this study was to investigate whether two barley products, whole-grain barley and barley malt, caused differentiation of the cecal microbiota in rats fed high-fat diets and whether there were correlations with the short-chain fatty acids formed. Methods and results: Male Wistar rats were given barley or malt (7-8 dietary fiber/100 g) for 4 weeks. Cellulose was used as a control, and the cecal microbiota was analyzed with next-generation sequencing of 16S rDNA. The barley group had higher abundances of Verru-comicrobia and Actinobacteria and lower abundances of Firmicutes and Deferribacteres than the control group; the alpha diversity was also lower. At the genus level, the barley group had higher abundances of Akkermansia, Ruminococcus, Blautia, and Bilophila. Turicibacter and Roseburia were more abundant in the malt group, and Parabacteroides, Dorea and rc4-4 were enriched in the control group. Most genera correlated with acetic and propionic acids, but Roseburia and Turicibacter instead correlated with butyric acid. Succinic acid correlated with Clostridium and Akkermansia. Conclusion: Bioprocessing is a potential method to modulate the gut microbiota for enhanced effects on human health.