Screening of Georgian Medicinal Mushrooms for their Antibacterial Activity and Optimization of Cultivation Conditions for the Split Gill Medicinal Mushroom, Schizophyllum commune BCC64

The present study aimed to evaluate the antibacterial activity (ABA) of new mushroom strains collected from the mountain and plain forests of Georgia and belonging to different taxonomic groups. Of 30 Basidiomycetes strains tested on agar plates, Schizophyllum commune BCC64 exhibited the highest inhibitory activity against Escherichia coli and Staphylococcus aureus by the diameter of inhibition zones (17 ± 1 mm and 19 ± 1 mm, respectively). Moreover, this mushroom showed strong activity against Staphylococcus enteritidis (11 mm), Pseudomonas aeruginosa (19 mm), and Salmonella epidermitidis (12 mm). In the submerged cultivation in synthetic medium, xylose and glucose ensured the highest ABA toward S. aureus (70% inhibition in microplate rider tests) and E. coli (60%), respectively. Among lignocellulosic materials tested in the submerged and solid-state fermentation, mandarin marc was found to be an excellent growth substrate for ABA accumulation by Sch. commune 64. Of six nitrogen sources, KNO3 favored the mushroom ABA increase against both bacteria. The suitability of the developed nutrient medium has been proven in 7 L fermenter. After fermentation, ethyl acetate extract obtained from culture liquid and ethanol extract obtained from mycelial biomass of Sch. commune 64 showed the best minimum inhibitory concentration (MIC) against E. coli (0.5 and 2.5 mg/mL, respectively) and S. aureus (1 mg/mL for both extracts).