Beneficial effects of protease preparations derived from Aspergillus on the colonic luminal environment in rats consuming a high-fat diet

The present study investigated the effects of the dietary addition of the protease preparations derived from Aspergillus on the colonic luminal environment. Rats were fed a 30% beef tallow diet with or without the protease preparations, including Amano protease (protease A 'Amano SD', neutral proteases from Aspergillus spp.) or orientase (orientase AY, acid proteases from Aspergillus niger) at the dose of 0.2% for 3 weeks. Cecal Bifidobacterium was significantly elevated in the dietary Amano protease group (194-fold, P< 0.05), but not in the orientase group. Lactobacillus was elevated in the two groups (P< 0.05). Cecal n-butyrate, propionate and lactate were higher in the Amano protease and orientase groups compared with the controls (P< 0.05). Fecal immunoglobulin A and mucins were elevated in the Amano protease group (P< 0.05). These results suggest the potential effect of the consumption of Aspergillus-derived protease preparations that are favorable for the colonic luminal environment in rats fed a high-fat diet.