Effect of Raspberry (Rubus indeaus L.) Juice Fermented by Limosilactobacillus fermentum FUA033 on the Human Gut Microbiota Cultured In Vitro: A Multi-Omics Approach

The gut microbiota plays important functions in human health and influences immune responses, metabolic processes, and several physiological activities. The modulation of the gut microbiota through dietary interventions has emerged as a promising approach, leading to significant interest in the development of functional foods that provide health benefits. In this context, our study investigated the effects of raspberry juice fermented by <i>Limosilactobacillus fermentum</i> FUA033 on the structure and metabolism of the gut microbiota. We performed 16S rRNA gene sequencing and nontargeted metabolomics analyses to evaluate changes in the microbial composition and metabolite profiles resulting from fermentation. Our findings revealed that fermented raspberry juice considerably increased the gut microbial diversity and promoted the abundance of beneficial genera. Fermentation substantially increased the production of short-chain fatty acids, such as acetate and butyrate, which increased from 30.09 ± 5.23 mmol/L to 43.07 ± 3.31 mmol/L, and from 7.72 ± 1.72 mmol/L to 15.01 ± 1.26 mmol/L, respectively. Metabolomic analyses also showed significant enhancements in amino acid metabolism pathways, particularly those involving tyrosine, arginine, and proline. These results highlight the potential of fermented raspberry juice as a functional food to improve gut health and metabolic functions.