Screening of antimicrobial membrane-active metabolites of soil microfungi by using chromatic phospholipid/polydiacetylene vesicles

Abstract

The focus of this study is screening of antimicrobial membrane-active metabolites of soil microfungi by using chromatic phospholipid/polydiacetylene vesicles. In this work, soil samples were collected from desert, forest, farm, lake shore and mineral zones of Northern and Central parts of Iran. These parts were not studied for antimicrobial potential of the soil isolates producing metabolites with membrane activity in particular, from microfungi. In the primary screening that was performed to evaluate the antimicrobial activity, isolates were analyzed in terms of their general inhibition effects to indicator strains including Escherichia coli, Candida albicans, and Saccharomyces cerevisiae. In the secondary screening, isolates producing membrane-active metabolites were determined using a Rapid Chromatic Detection method. The chromatic technology is simple and this method provides a rapid and easy evaluation of interactions between antimicrobial membrane-active metabolites and lipid layers of vesicles as well. A total number of 59 species of fungi was isolated from the soil samples. It has been found that 20 isolates were effective against indicator strains. Based on color and fluorescence changes that are easily identified by the naked eye and fluorescent microscopy and can be recorded by UV-Vis spectrophotometery, one fungus showed antimicrobial membrane-activity effect against some of the indicator strains. This isolate was identified to the genus level that belonged to Aspergillus. As resistance is barely developed against membrane-active antibiotics, in this paper, we demonstrated the application of the chromatic vesicle model for screening of antimicrobial membrane-active metabolites as potential new antibiotics from soil microfungi.