A Glycolipid‐Like Biosurfactant Molecule Derived From an Exophiala spinifera Strain With Significant Antibiofilm, Antifungal, and Antiquorum Sensing Activities

Abstract

A biosurfactant‐producing fungal strain, Exophiala spinifera CSF123, was isolated from cashew oil‐contaminated soil. Internal transcribed spacer sequencing followed by phylogenetic analysis revealed that the isolated fungus shared 98.42% similarity with E. spinifera CBS66.76. The biosurfactant molecule, named ES‐414, produced by the fungus was purified to homogeneity by HPLC, and subsequent electrospray mass spectrometric analysis showed that its neutral mass is 414 Da. The molecule displayed remarkable antibiofilm activity. At concentrations of 15 and 80 μg/mL, ES‐414 showed 62.17% biofilm inhibition against Candida tropicalis and 66% inhibition against Candida albicans, respectively. It also displayed significant antifungal properties against C. albicans, C. tropicalis, Candida glabrata, Candida parapsilosis, and Candida krusei. ES‐414, in a dose‐dependent manner, inhibited the quorum sensing activity of Chromobacterium violaceum. Thermogravimetric analysis of ES‐414 indicated that the molecule remains stable up to 240°C. Detailed structural characterization using GC‐MS, FTIR, UV‐visible spectroscopy, elemental analysis, Molisch test, TLC analysis, and solubility studies indicated that ES‐414 is a glycolipid‐like molecule.