The transcriptomic profile of Pseudozyma aphidis during production of mannosylerythritol lipids

Pseudozyma aphidis is one of the most productive microbial producers of mannosylerythritol lipids on vegetable oils with a unique product spectrum that contains all four main variants MEL-A, -B, -C and -D. Secretion of MEL is thereby accompanied by a morphologenetic switch from yeast to hyphal growth. To investigate the genetic characteristics of MEL secretion and dimorphic transition, we analyzed the transcriptome of P. aphidis during production of MEL after the morphologenetic switch. The analysis revealed that the strong activation of 4 of the 5 genes within the MEL-cluster is clearly dependent on the presence of a hydrophobic carbon source. Only the acetyltransferase mat1 is not induced. This may explain the heterogeneous mixture of MEL with different degree of acetylation. In parallel to the MEL-Cluster, we saw a significant induction of a large group of genes which are coding for cell wall modifying enzymes. These genes were mainly grouped in two large gene clusters typical for the concerted cellular switch. In addition, a group of transcription factors was activated which may be key regulator candidates for MEL-synthesis and cell development. The induction of nitrogen metabolism and assimilation processes for phosphate, iron and other nutrients draw a picture of further cellular requirements at this time point. As part of this work, we present the manually annotated and experimentally verified genome and transcriptome of P. aphidis DSM 70725 with a total number of 6942 genes. 82 % of the genes are othologs to Pseudozyma antarctica and 73 % orthologs to Ustilago maydis. Experimental annotation of transcriptional landscape combined with examination of gene expression on two different carbon sources.