Antifungal Effect of Lipopeptide Compounds Produced by Bacillus amyloliquefaciens M13RW01

Aims: Bacillus amyloliquefaciens lipopeptide are made of amino acids and fatty acid chain, and have many antifungal activities against several important pathogenic yeasts. The present research was carried out with the aim of extraction and evaluation of antifungal effect of lipopeptide compounds produced by Esfahan native Bacillus amyloliquefaciens M13RW01 against Candida albicans, Candida glabrata, Candida krusei, Candida parapsilosis, and Candida tropicalis.
In this experimental study, Bacillus amyloliquefaciens M13RW01 was cultured in modified Peptone-Glucose-Yeast extract medium (PGY) for 72 hours. Then, the lipopeptide compounds produced in the medium by precipitation with HCl 6M were extracted and dissolved in methanol (50% water; 50% methanol). The antifungal activity of lipopeptide compounds against 5 species of Candida was investigated by well diffusion method, Minimum Inhibitory Concentration (MIC), and Minimum Fungal Concentration (MFC). Also, germ tube production by Candida albicans in tube containing lipopeptide was investigated.
Findings: The Bacillus amyloliquefaciens M13RW01 lipopeptide metabolites inhibited germ tube production in all C. albicans yeasts, but no inhibitory or fatal effect was observed on other species of Candida. Inhibition zone was not observed around the wells; in all dilutions, Candida yeasts grew. Therefore, minimal inhibitory concentration and minimal fungicidal concentration were not determined.
The lipopeptide metabolites produced by Bacillus amyloliquefaciens M13RW01 have no inhibitory or fungal effects on the studied species of Candida, but inhibit the germ tubes production by Candida albicans yeast.