Advances in in batch culture fermented Coriolus versicolor medicinal mushroom for the production of antibacterial compounds

Abstract

Bioactive compounds obtained from Coriolus versicolor (Trametes versicolor (L: Fr) Lloyd, 1920.) mushrooms cultivated in a stirred-tank bioreactor were tested to determine their antimicrobial potential. Extracellular polysaccharides were isolated from the fermentation broth by ethanol precipitation. A methanol extract was prepared from mycelium. The cultivation conditions applied during the fermentation process provided for significant biomass 6.63 +/- 0.31 g dry weight L-1 and yield of extracellular polysaccharides (EPS) (0.74 +/- 0.12 g L-1). Microscopic analyses revealed that the mycelium grew predominately in the form of fluffy pellets. The methanol extract demonstrated very good activity against all the tested Gram-positive bacteria. Bacillus spizizeni and Staphylococcus epidermidis were the most sensitive strains (minimum inhibitory concentration (MIC) lt 0.3125 mg mL(-1)). Among the Gram-negative bacteria, Yersinia enterocolitica had the lowest MIC value, 5 mg mL(-1). Microbicidal activity of mycelia methanol extract was established in seven out of ten tested Gram-negative bacteria strains with minimum bactericidal concentration (MBC) values ranged from 20 to 40 mg mL(-1). Enterococcus faecalis and Staphylococcus aureus showed higher sensitivity to the extracellular polysaccharides (MIC values 2.5 mg mL(-1)). FTIR analysis revealed a more complex chemical composition of the methanol extract compared to EPS, which might explain the better antibacterial activity of the methanol extract. Our results suggested that the submerged cultivation of Coriolus versicolor followed by ethanol precipitation of EPS and the methanol extraction of mycelia can be a promising process to obtain biological active compounds with significant antimicrobial activity. Industrial Relevance: Mushrooms contain a large number of chemicals with potential use as antimicrobial compounds. One of the biggest challenges for providing biologically active compounds from mushrooms is short-term process standardization with a low risk for contamination. Submerged culture cultivation is the best choice for providing antimicrobial compounds from mushrooms. The submerged culture method represents an effective and energy-efficient means to produce novel antibacterial compound from mushrooms. Antibacterial activity testing revealed that methanol extract and isolated exopolysaccharides exhibited strong antibacterial activity, especially against Gram-positive bacteria.