Antimicrobial Activities of Laetiporus conifericola (Agaricomycetes) from the United States.

In this study, samples of polypore mushroom Laetiporus conifericola were collected from Pennsylvania, USA. The antimicrobial activity (AMA) of ethanolic, methanolic, and water extracts of this fungus were tested in vitro by the agar diffusion test against some selected clinically important microorganisms. These microorganisms included three Gram-positive bacteria (Staphylococcus aureus 5W1941, S. epidermidis 85W1940, and Bacillus cereus 85W1815), three Gram-negative bacteria (Escherichia coli 85W1860, Salmonella typhimurium 85W1956, and Pseudomonas aeruginosa 85W1903), and one fungus (Candida albicans). These extracts demonstrated varying degrees of inhibition against all of the test pathogenic microorganisms except C. albicans. Methanolic and ethanolic extracts of L. conifericola were very effective against S. aureus, while the aqueous extract was the least effective. All tested extracts were effective against S. epidermidis, methanolic extract produced the best zone of inhibition followed by the aqueous extract while ethanolic extract had the least zone of inhibition. B. cereus and P. aeruginosa were highly susceptible to ethanol extract. In addition, the growth of E. coli was best inhibited by the aqueous extract, followed by the methanolic and ethanolic extracts, respectively. The aqueous and methanolic extracts were most effective against S. typhimurium; however, this bacterium was not susceptible to ethanolic extract. The significance of these findings is discussed.