In vitro fermentation of whole matrix, digested products and β-glucan enriched extract of Pleurotus eryngii mushrooms distinctively impact the fecal microbiota of healthy older adults

Pleurotus eryngii (PE), an edible mushroom rich in bioactive compounds, has been shown to exert immunomodulatory, anti-inflammatory, antioxidant, anti-carcinogenic, anti-microbial, antihepatotoxic and hypolipidemic activities, all important for the well-being of the ageing population. This study assessed in vitro the prebiotic-like effects of multiple forms of this mushroom. An in vitro static batch fermentation was performed for 24 h with faecal inocula from five apparently healthy older adults in the presence of the following PE forms: whole food matrix (PEWS), in vitro digested (PEWSD) and rich in β-glucans extract (PEWSE). The changes in bacterial communities upon fermentation at family, genera and species level were detected via 16S rRNA Next Generation Sequencing and Quantitative real-time PCR. Short-chain fatty acids (SCFAs) were quantified using gas chromatography (GC), whereas other metabolites were analysed through ultra-high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). DEseq2 analysis indicated that PEWS presence exhibited the largest impact on faecal microbial families' and genera's abundance compared to negative (non-carbon source) and positive (inulin) controls. Only PEWS significantly increased Bifidobacterium spp. and F. prausnitzii populations, while all three forms robustly increased Bacteroides spp. levels and levels of butyrate, acetate and propionate acids. Statistical significance was set at p < 0.05. Overall, the findings highlight the beneficial effect of PE on intestinal health of older adults supporting its potential incorporation into innovative functional foods. However, additional in vivo studies are required to substantiate these findings before translating them into dietary guidelines or clinical applications.