Efficient production of tri-acetylated mono-acylated mannosylerythritol lipids by Sporisorium sp. aff. sorghi SAM20

Aims: The aim of this study was to isolate a novel yeast strain, evaluate biosurfactant production by the strain and characterize the major product. Methods and Results: The strain SAM20, isolated from grass, identified as Sporisorium sp. aff. sorghi based on phylogenetic analyses. The strain produced approximately 32 g l−1 glycolipid biosurfactants from 40 g l−1 soybean oil after 7 days at 28°C. The glycolipids showed a unique pattern of mannosylerythritol lipids (MELs) on thin layer chromatography plate compared to those hitherto reported. Structural characterization of the major product, called GL-A, revealed that it was mainly tri-acetylated mono-acylated MELs (MEL-A2) with C14:0, C16:0, C12:0 or C14:1 as the hydrophobic chain. The critical micelle concentration (CMC), the surface tension at CMC and hydrophilic–lipophilic balance value for GL-A were estimated to be 20 mg l−1, 30·0 mN m−1 and 8·7, respectively. Conclusions: A MEL-A2 with novel composition and surface activities was efficiently produced from a novel MEL producer. This is the first report on production of MEL-A2 as the major product and from soybean oil. The biosurfactant has potential application as a wetting agent and oil-in-water emulsifier. Significance and Impact of the Study: Discovery of novel structures and novel strains is valuable for further commercial development and application of MELs. Sporisorium sp. aff. sorghi SAM20 can be considered as a potential candidate for commercial production of biosurfactants