[Antimicrobial potential of Metarhizium taii in vitro].

Objective: To investigate the antimicrobial potential of Metarhizium tail and its corresponding active fractions.

Methods: The agar diffusion method and growth-rate assay were employed individually to measure the antibacterial and antifungal activities of M. taii. The microdilution and disk colony count was used to test the minimal inhibitory concentration and minimal bacterial concentration.

Results: The extraction fractions of M. tail could evidently inhibi the growth of Gram positive bacteria such as Staphylococcus aureus, Bacillus subtilis, Gram negative bacteria such as Escherichia coli, Pseudomonas aerzginosa, and Klebsiella pneumoniae, and Enterococcus faecalis,and phytopathogenic fungi such as Rhizoctonia solani, Fusarium oxysporum, hereby M. taii had a broad spectrum antimicrobial effect including potent antibacterial and antifungal activities. The antimicrobial active ingredients of M. tail mainly existed in three extraction fractions including ethyl acetate extract in fermented broth, chloroform, and ethyl acetate extracts in mycelia. However there was an evident discrepancy on the antibacterial spectrum and competence for different active extraction fractions.

Conclusion: M. taii possess potent and broad-spectrum antimicrobial potential, and it is a good edible and medicinal resource for the functional food development and the discovery of new antimicrobial drug.