Study of the impact of edible mushroom biomass obtained from by-products upcycling on the human intestinal microbiota

In recent years, there has been a rise in the consumption of mushrooms, leading to an increase in the production of related by-products. Given their nutritional profile, mushrooms have the potential to represent a novel source of dietary fiber, which has been linked to prebiotic benefits. Through the utilization of a human feces’ fermentation model, this study aimed to assess the possible prebiotic effect of by-product-derived mushroom biomass. To accomplish this, by-products from 2 types of mushrooms, namely Pleurotus ostreatus and Pleurotus eryngii (attained after different extraction procedures - M1 and M2), were nutritionally characterized, with a particular emphasis on the fiber, structural carbohydrates, and glucans content (components known to be used as a substrate by microbiota microorganisms and for their prebiotic potential). The results showed that P. ostreatus possessed a marginal advantage over P. eryngii in terms of fiber content (P. ostreatus: 36.39 – 41.01% DW; P. eryngii: 35.19 – 39.69 % DW) and higher levels of β-glucans (P. ostreatus: 50.92 - 52.29 % DW; P. eryngii: 41.96 - 43.64 % DW). When comparing the flours, it was found that the M2 extraction process produced flour with higher quantities of structural carbohydrates and fiber. Therefore, the 2 P. ostreatus’ flours were selected and submitted to a simulated digestive process and tested in an in vitro human fecal fermentation model considering fluctuations in the microbiota (Firmicutes, Bacteroidetes, Lactobacillus, Bifidobacterium, and Clostridium) profile, and the formation of short-chain fatty acids (SCFAs) and other relevant organic acids. Overall, the impact of mushrooms flours on gut microbiota led to a Firmicutes to Bacteroidetes ratio consistently close to 1, which supports their prebiotic potential. The SCFA (acetate, butyrate, and propionate) production also revealed a positive modulation of the microbiota metabolism. There was an increase in all metabolites (except for lactic acid) compared to the controls, indicating the flour’s prebiotic potential, even It is essential to note that the process of valuing mushroom by-products of mushroom in a zero-waste approach permitted the production of added-value extracts and the use of the residual biomasses as a functional prebiotic ingredient that might be used in new functional foods.