Abstract
Pseudozyma antarctica is a nonpathogenic phyllosphere yeast known as an excellent producer of industrial lipases and mannosylerythritol lipids (MELs), which are multi-functional glycolipids. The fungus produces a much higher amount of MELs from vegetable oil than from glucose, whereas its close relative, Ustilago maydis UM521, produces a lower amount of MELs from vegetable oil. In the present study, we used previous gene expression profiles measured by DNA microarray analyses after culturing on two carbon sources, glucose and soybean oil, to further characterize MEL biosynthesis in P. antarctica T-34. A total of 264 genes were found with induction ratios and expression intensities under oily conditions with similar tendencies to those of MEL cluster genes. Of these, 93 were categorized as metabolic genes using the Eukaryotic Orthologous Groups classification. Within this metabolic category, amino acids, carbohydrates, inorganic ions, and secondary metabolite metabolism, as well as energy production and conversion, but not lipid metabolism, were enriched. Furthermore, genes involved in central metabolic pathways, such as glycolysis and the tricarboxylic acid cycle, were highly induced in P. antarctica T-34 under oily conditions, whereas they were suppressed in U. maydis UM521. These results suggest that the central metabolism of P. antarctica T-34 under oily conditions contributes to its excellent oil utilization and extracellular glycolipid production.
Highlights
The gene expression intensities revealed that genes related to central metabolic pathways such as glycolysis and the tricarboxylic acid cycle (TCA) were upregulated in P. antarctica T-34 when compared to U. maydis UM521 under oily conditions
To demonstrate the transcriptomic regulatory characteristics of P. antarctica T-34 under oily conditions that result in the production of mannosylerythritol lipids (MELs), we focused on genes that were differentially regulated between P. antarctica T-34 and U. maydis UM521, using the DNA microarray data
The genes responsible for central metabolic pathways such as glycolysis, the TCA cycle, the glyoxylate shunt, and the anaplerotic reaction were highly expressed in P. antarctica T-34, regardless of whether the carbon source was glucose or soybean oil, whereas these genes were not induced in U. maydis UM521, which could be the reason for poor growth and lower MEL production under oily conditions
Summary
Pseudozyma antarctica is a basidiomycetous yeast belonging to Ustilaginomycetes, which includes the corn smut fungus, Ustilago maydis [1,2], and is known to extracellularly produce lipases and a biodegradable plastic-degrading enzyme that hydrolyzes. It should be noted that a closely related fungus, Ustilago maydis UM521, produces lower amounts of MELs from vegetable oils than yeast strain of the genus Pseudozyma, including the strain T-34. Using gene set enrichment analysis, the gene sets related to fatty acid metabolism were significantly upregulated in the presence of vegetable oil, and the gene cluster for MEL biosynthesis was highly expressed in P. antarctica T-34, regardless of whether the carbon source was glucose or soybean oil (Fig 1). The gene expression intensities revealed that genes related to central metabolic pathways such as glycolysis and the tricarboxylic acid cycle (TCA) were upregulated in P. antarctica T-34 when compared to U. maydis UM521 under oily conditions These results suggest that P. antarctica T-34 is adapted to aerobically produce larger amounts of MELs from vegetable oil by modification of its central metabolic system. Insight into the oil utilization capacity of microorganisms will lead to more effective strategies for using feedstocks to produce functional bio-based materials
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
