ABSTRACT
This study assessed the antioxidant properties and antibacterial effects of hot water, cold water, and ethanol extracts of Agaricomycetes mushrooms Trametes betulina, Pleurotus ostreatus, Agaricus bisporus var. albidus, and A. bisporus var. avellaneus against Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae. The mushroom extracts were assessed for total phenolic content as well as 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide scavenging activities. The multiantibiotic resistance index (MARI) of the bacterial isolates was assessed and the antimicrobial activity of the mushroom extracts was assayed with the agar disc diffusion method. The agar well diffusion assay was performed to determine their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The test bacteria were multidrug resistant against antibiotics, with P. aeruginosa having the highest MARI followed by K. pneumoniae and E. coli. Cold water extracts showed a better antibacterial effect compared to the others and a concentration/effect correlation was observed (from 5 to 500 mg/mL). Ethanol extracts from P. ostreatus and hot water extracts from T. betulina were the most effective in inhibiting and lysing E. coli and K. pneumoniae, respectively, at a MIC and MBC of 3.90 mg/mL. The tested extracts, especially P. ostreatus extract, showed high DPPH and hydrogen peroxide scavenging potential as well as high total phenolic content compared to standard antioxidants. This study showed that the screened agaricomycetous mushrooms possess antibacterial activity against bacterial pathogens as well as antioxidant activity due to their high phenolic content.
