Prebiotic properties and antioxidant effect of crude extracts and polysaccharides from Agaricus bisporus and Pleurotus ostreatus mushrooms

Abstract

Modifying the gut microbiome, also known as bacteriotherapy, is a key strategy that uses probiotics, prebiotics, or synbiotics to reduce inflammation and fight infection and colonization by pathogenic bacteria. Various food sources, particularly those rich in Lactobacillus species, are well-recognized for their probiotic properties. Edible mushrooms are rich with their nutrient-dense composition, including carbohydrates, proteins, fibers, minerals, vitamins, and lipids, which stand out as a promising bio-source for several biological uses. In this study, four probiotic strains were isolated and identified from food samples: Lactobacillus acidophilus (L. acidophilus), L. pentosus, L. plantarum, and L. paracasei. Then the prebiotic and antioxidant properties of crude and polysaccharide extracts were assessed from two edible mushrooms, Agaricus bisporus (brown) and Pleurotus ostreatus (oyster). Using the phenol-sulfuric acid method, the ethanol extract of P. ostreatus exhibited the highest yields of total carbohydrates and reducing sugars (6.14 and 3.15 mg/mL, respectively). Among the mushroom extracts, the polysaccharide from A. bisporus demonstrated the strongest radical scavenging activity (93.73%), with a half-maximal effective concentration (EC₅₀) of 0.19 mg/mL, measured using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. The prebiotic properties of the mushroom extracts were evaluated by their ability to promote probiotic growth and inhibit pathogenic bacteria. The polysaccharide extracts from A. bisporus and P. ostreatus significantly stimulated the growth of L. paracasei (1.99 and 2.04 nm, respectively). Additionally, the cell-free supernatant from L. acidophilus cultured with the A. bisporus polysaccharide extract exhibited the highest antimicrobial activity, producing a 36.33 mm inhibition zone against the pathogen L. monocytogenes. These findings demonstrate that polysaccharides from A. bisporus and P. ostreatus are promising candidates for functional food development. These extracts offer a multifaceted approach to promoting gut health and reducing oxidative stress through selectively stimulating beneficial Lactobacillus species while inhibiting the growth of pathogens and exerting significant antioxidant effects.