Comparative evaluation of antifungal and antibacterial activities of crude extracts of Pleurotus sajor-caju, Pleurotus tuber-regium and Lentinus squarrosulus (Basidiomycota, Pleurotaceae, Lentinaceae) from Cameroon

Antifungal and antibacterial activities of crude extracts of 3 tropical mushrooms including Pleurotus sajor-caju, Pleurotus tuber-regium and Lentinus squarrosulus were investigated on eleven species of bacterial and three of fungal human pathogens. For the pathogenic fungi, the Minimal Inhibitory Concentration (MIC) of carpophore extracts ranged from 0.39 mg/mL to 6.25 mg/mL for Candida albicans, 0.78 mg/mL to 6.25 mg/mL for Aspergillus fumigetus, and 1.56 mg/mL to 6.25 mg/mL for Aspergillus ochraceus. For bacteria, the MIC values ranged from 6.25 mg/mL to 12.5 mg/mL on most Gram positive strains including Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus and Mycobacterium smegmatis. This MIC value was the same (12.5 mg/mL) for the 3 crude extracts tested on Staphylococcus epidermidis for the Gram positive strains. Gram negative bacteria were generally less sensitive to crude extracts with higher MIC values ranging from 6.25 mg/mL to 12.5 mg/mL for Escherichia coli and Enterobacter cloacae and the same (12.5 mg/mL) for Proteus vulgaris, Klebsiella oxytoca, Klebsiella aerogenes and Proteus mirabilis. Based on the above mentioned figures, it appears that strains of pathogenic fungi tested are generally much more sensitive to crude extracts than strains of bacteria. In fact, antimicrobial activities of the 3 crude extracts tested are stronger on human pathogenic fungi than bacteria. These results are evidence that carpophores of the 3 mushrooms species could be a source of new molecules potentially more effective than synthetic products against some human pathogenic fungi and bacteria.