Effects of Rich in Β-Glucans Edible Mushrooms on Aging Gut Microbiota Characteristics: An In Vitro Study

Abstract

Alterations of gut microbiota are evident during the aging process. Prebiotics may restore the gut microbial balance, with β-glucans emerging as prebiotic candidates. This study aimed to investigate the impact of edible mushrooms rich in β-glucans on the gut microbiota composition and metabolites by using in vitro static batch culture fermentations and fecal inocula from elderly donors (n = 8). Pleurotus ostreatus, P. eryngii, Hericium erinaceus and Cyclocybe cylindracea mushrooms derived from various substrates were examined. Gut microbiota composition (quantitative PCR (qPCR)) and short-chain fatty acids (SCFAs; gas chromatography (GC)) were determined during the 24-h fermentation. P. eryngii induced a strong lactogenic effect, while P. ostreatus and C. cylindracea induced a significant bifidogenic effect (p for all <0.05). Furthermore, P. eryngii produced on wheat straw and the prebiotic inulin had comparable Prebiotic Indexes, while P. eryngii produced on wheat straw/grape marc significantly increased the levels of tested butyrate producers. P. ostreatus, P. eryngii and C. cylindracea had similar trends in SCFA profile; H. erinaceus mushrooms were more diverse, especially in the production of propionate, butyrate and branched SCFAs. In conclusion, mushrooms rich in β-glucans may exert beneficial in vitro effects in gut microbiota and/or SCFAs production in elderly subjects.

Genoprotective Properties and Metabolites of β-Glucan-Rich Edible Mushrooms Following Their In Vitro Fermentation by Human Faecal Microbiota

“…The genera Pleurotus and Cyclocybe, selected for analysis in the present work, produce mushrooms rich in β-glucans which were very recently shown to exhibit a beneficial influence on the composition of gut microbiota of apparently healthy subjects over 65 years old (i.e., increase of Bifidobacterium spp. and F. prausnitzii populations) [35]. Interestingly, correlation analysis revealed significant positive associations of mean Prebiotic Indexes values of these mushrooms with their average total glucan and β-glucan content [35].…”

“…The aqueous phase of human stool (faecal water) is known to be cytotoxic mainly due to the contained bile acids [40]. Furthermore, in vitro fermentation of the mushrooms selected to be analysed in this work, as well as of inulin, resulted in significantly higher levels of total volatile fatty acids (VFAs) [35]. Therefore, it is not surprising that NC and both inulin or P. ostreatus 1123 fermentation supernatant (FS) were also cytotoxic to CaCo-2 cells, in a dose-and time-dependent manner ( Figure 2).…”

“…and F. prausnitzii populations) [35]. Interestingly, correlation analysis revealed significant positive associations of mean Prebiotic Indexes values of these mushrooms with their average total glucan and β-glucan content [35]. All fungal strains selected to be used as carbon sources in the respective in vitro static batch culture fermentation were cultivated on a wheat straw-based substrate and produced mushrooms with β-glucan contents exceeding 30% (d.w.) ( Figure 1, Supplementary Table S1).…”

“…Inulin and all tested mushrooms demonstrated positive mean Prebiotic Indexes (PIs), with higher levels detected in the case of the prebiotic inulin, P. eryngii and C. cylindracea (CC2, CC505) mushrooms. Inulin (p = 0.005) and P. eryngii (p = 0.021) resulted in significantly higher PIs compared to NC and induced positive PIs results in all 8 runs of the experiment [35]. The effect of pooled pre-(t = 0 h) or post-fermentation (t = 24 h) supernatants on Caco-2 cells' viability was evaluated at increasing concentrations of 1%, 2.5% and 5% v/v after 48 h of incubation.…”

“…In the context of a pilot study, in vitro static batch fermentations were carried out for 24 h, as previously described [35], in order to evaluate the effect of fermentation supernatants (FSs) on Caco-2 cell proliferation and subsequently study their genotoxicity. Batch fermentations were performed with different concentrations of the prebiotic inulin (INU) (0.5% w/v and 2% w/v) and lyophilised P. ostreatus 1123 powder (0.5% w/v, 1% w/v and 2% w/v), utilising faecal inocula from one healthy donor.…”