Genomic annotation of a mannosylerithritol lipid yeast producer as an approach to unravel its metabolic pathway

Mannosylerithritol lipids (MELs) are amphiphilic molecules of interest to industry due to their broad range of potential applications, including use as biosurfactants. MEL production has been reported in Ustilaginomycetes as a secondary metabolite, involving a biosynthetic cluster of five genes. There are four types of MELs, categorized as A to D, each of which varies according to the number of acetylations and acylations. MELs are produce as mixtures of the four types at different ratios depending on the species. We have focused our study into the mechanisms behind MEL production on Pseudozyma graminicola, which has been reported to primarily produce MEL-C (85%). We sequenced and assembly its genome, using the PacBio platform, into 34 contigs with a total of 19.57 Mb. Subsequently, RNAseq data, was used to facilitate gene calling and annotation leading to the identification of 6602 genes. We have identified the MEL cluster, as well the presence of pathogenic clusters which has been reported in species such as U. maydis and S. reilianum. From our phylogenic analysis we have observed that P. graminicola shares more synteny to the aforementioned species than to other Pseudozyma. However, unlike U. maydis and S. reilianum, P. graminicola is reported to be an endophyte and not a biotrophic pathogen. In addition to genome characterization we have developed a transformation protocol and used this to investigate the role of genes putatively involved in MEL production, including three regulatory genes. Intriguingly, three of the mutants have very strong morphological phenotypes. We will report our findings, including the impact of these mutants on MEL production.