Mushroom residue extract-based media enhanced the enrichment and isolation of cellulose-degrading bacteria

Abstract

This study aims to develop substrate-specific media for targeted enrichment of cellulose-degrading bacteria from mushroom residue to increase composting efficiency. Mushroom residue extract-based media—MR (basic extract) and MRC (with sodium carboxymethyl cellulose)—were designed and comparatively analyzed against conventional LB medium. Both MR and MRC significantly increased bacterial alpha diversity and enriched key cellulose-degrading genera (e.g., Paenibacillus and Bacillus). Functional shifts were observed through the altered abundance of carbon-degrading genes (abfA, cex, lig) and nitrogen/phosphorus metabolism genes (nifH, gcd), indicating metabolic adaptation to lignocellulose-rich substrates. Critically, 35 cellulose-degrading strains with superior enzymatic activities were isolated (endoglucanase: 32.77–144.88 μg min⁻¹; β-glucosidase: 49.99–122.34 μg min⁻¹; filter paper activity: 38.82–169.34 μg min⁻¹). Compared with LB-derived isolates, strains from MR/MRC media presented a 1.8–2.3-fold greater cellulose-degrading capacity. These findings demonstrate that substrate-specific media preferentially enrich functional consortia, providing tailored inoculants to accelerate composting and valorize agricultural waste.