Antibacterial activity of Pleurotus species

Basidiomycetes express promising antitumor, immune modulating, cardiovascular and hypercholesterolemia, antiviral, antibacterial and antiparasitic effects (Wasser & Weis, 1999; Reshetnikov et al., 2001; Wasser, 2002, Didukh et al., 2003). They are also well known for their safety and efficacy as functional foods and dietary supplements (Wasser & Akavia, 2008). The antibacterial and antiviral value of different genera of Basidiomycetes has been tested by different authors (Benedict & Brady, 1972; Donnelly et al., 1986; Gao et al., 2003;). In particular the antibacterial and antiparasitic therapeutic effects were investigated in the genera Flammulina P. Karst, Fomes (Fr.) Fr., Ganoderma P. Karst., Grifola Gray, Lentinus Fr., Piptoporus P. Karst, Schizophyllum (Fr.), Trametes Fr., and Volvariella (Fr.) P. Kumm. (Wasser & Weis, 1999). As regards the genus Pleurotus (Fr.) P. Kumm., the basidiomata of Pleurotus ostreatus (Jacq.) P. Kumm. shows antibacterial and antiparasitic effects as non-commercially developed mushroom product. The extracts of P. ostreatus EVFB1 and EVFB4 were tested by Vamanu et al. (2011) proved narrow antibacterial activity against Gram-negative and Gram-positive bacteria such as Escherichia coli CBAB 2, Bacillus cereus CMGB 215, and Listeria innocua CMGB 218. The antimicrobial activity of P. eryngii var. ferulae grown on various agrowastes were investigated by Akyuz & Kirbag (2009) on Bacillus megaterium DSM 32, Staphylococcus aureus COWAN 1, Escherichia coli ATCC 25922, Klebsiella pneumoniae FMC 5, Candida albicans FMC 17, Candida glabrata ATCC 66032, Trichophyton spp., and Epidermophyton spp. This abstract focusing on antibacterial activity of Pleurotus species growing as saprophytes on rot roots of plants of Apiaceae family. The basidiomata of P. eryngii (DC.) Quél. var. eryngii, P. eryngii var. ferulae (Lanzi) Sacc., P. eryngii var. elaeoselini Venturella, Zervakis & La Rocca and, P. nebrodensis (Inzenga) Quél., were collected in pastures and meadows of Sicily. This is as special group of Pleurotus mushrooms which appears in nature in close association with plants of family Apiaceae,. In particular, species like P. eryngii var. eryngii and P. nebrodensis are typical constituents of the Mediterranean fungal diversity and are particularly popular as choice edible mushrooms (Zervakis & Venturella, 2002). The complete mushroom basidiomata (cap, gills, and stipe) were cleaned of debris (without washing) with a knife, and kept at minus 80°C prior to sample preparation. To extract the cationic peptides, 500 mg of freeze-dried mushrooms were dissolved in 5 ml of extraction solution (10% acetic acid in phosphate saline buffer) and sonicated for 1 min at 0°C (1 pulse s 1, 70% duty cycle) and centrifuged at 27,000 g for 30 min at 4°C to remove any precipitate. After centrifugation, the supernatants were freeze-dried to be later redissolved in H2O. The extracts were tested for their in vitro growth inhibitory activity against a group of bacterial reference strains (Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis RP62A, Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC10536) of medical relevance. Minimal inhibitory concentrations (MICs), determined by using a broth dilution micro-method, ranged from 0.025% to 25% v/v. Further studies are in progress to evaluate their activity against the biofilm mode of growth of above mentioned pathogens.