Evaluation of the efficiency of the extract from three species belonging to oyster mushrooms, Pleurotus spp, against some pathogenic bacteria

Abstract

This study aimed to evaluate the efficacy of secondary metabolites extracted from the Spent Mushroom Substrate (SMS) of three oyster mushroom species (Pleurotus ostreatus, P. florida, and P. sapidus) to inhibit the growth of pathogenic bacteria. The extracts were prepared using methanol 85%, ethanol 85%, and aqueous solvents at two concentrations: 50 µg/mL and 100 µg/mL. The antimicrobial activity of these extracts was tested against two pathogenic bacterial strains, Pseudomonas aeruginosa and Staphylococcus aureus, using an agar-well diffusion assay to determine the minimal inhibitory concentration (MIC). The results showed varying degrees of antibacterial activity among the SMS extracts. At high concentrations (100 µg/mL), a methanolic extract of P. ostreatus exhibited the highest activity, with inhibition zones of 22.5 mm against S. aureus and 20.3 mm against P. aeruginosa. P. florida showed inhibition zones of 21.8 mm against S. aureus and 20.7 mm against P. aeruginosa. P. sapidus displayed moderate antibacterial activity, with inhibition zones of 20.3 mm against S. aureus and 20.1 mm against P. aeruginosa. Other extracts also showed varying inhibition for both bacterial species. On the other hand, the cold aqueous extract recorded the lowest inhibition zone; P. ostreatus recorded an inhibition of 12.2 and 14.7 mm for S. aureus and P. aeruginosa strains, respectively, while P. florida recorded 10.2 and 10.6 mm, respectively, and P. sapidus recorded 9.2 and 9.4 mm, respectively. These findings suggest that methanolic extracts of SMS from P. ostreatus exhibited the most potent antimicrobial activity, highlighting its potential as a natural antimicrobial agent.