Abstract
Pseudozyma antarctica is a non-pathogenic phyllosphere yeast known as an excellent producer of mannosylerythritol lipids (MELs), multi-functional extracellular glycolipids, from vegetable oils. To clarify the genetic characteristics of P. antarctica, we analyzed the 18 Mb genome of P. antarctica T-34. On the basis of KOG analysis, the number of genes (219 genes) categorized into lipid transport and metabolism classification in P. antarctica was one and a half times larger than that of yeast Saccharomyces cerevisiae (140 genes). The gene encoding an ATP/citrate lyase (ACL) related to acetyl-CoA synthesis conserved in oleaginous strains was found in P. antarctica genome: the single ACL gene possesses the four domains identical to that of the human gene, whereas the other oleaginous ascomycetous species have the two genes covering the four domains. P. antarctica genome exhibited a remarkable degree of synteny to U. maydis genome, however, the comparison of the gene expression profiles under the culture on the two carbon sources, glucose and soybean oil, by the DNA microarray method revealed that transcriptomes between the two species were significantly different. In P. antarctica, expression of the gene sets relating fatty acid metabolism were markedly up-regulated under the oily conditions compared with glucose. Additionally, MEL biosynthesis cluster of P. antarctica was highly expressed regardless of the carbon source as compared to U. maydis. These results strongly indicate that P. antarctica has an oleaginous nature which is relevant to its non-pathogenic and MEL-overproducing characteristics. The analysis and dataset contribute to stimulate the development of improved strains with customized properties for high yield production of functional bio-based materials.
Highlights
Pseudozyma antarctica is an anamorphic basidiomycetous yeast belonging to the Ustilagomycetes, a group that includes the smut fungus Ustilago maydis [1,2]
The 219 genes were categorized into the lipid transport and metabolism classification, while 140 genes were in the same category in S. cerevisiae, indicating P. antarctica potentially possesses the expanded lipid metabolism pathway (Fig. 2, Table S1)
A gene encoding ATP/citrate liase (ACL), which has been known that oleaginous species could synthesize acetyl-CoA via ATP/citrate lyase (ACL) for fatty acid synthesis, was found in P. antarctica genome, besides the genes is not conserved in non-oleaginous species such as S. cerevisiae [37,48,49]
Summary
Pseudozyma antarctica is an anamorphic basidiomycetous yeast belonging to the Ustilagomycetes, a group that includes the smut fungus Ustilago maydis [1,2]. Of the genus Pseudozyma, P. antarctica was initially isolated on the bottom of a lake in Antarctica as Candida antarctica, and found to produce industry-relevant extracellular lipases at high levels. Their modification was thoroughly investigated to enhance the efficiency of the reaction and expand their industrial application [7,8,9]. The extracellular production of an excellent biodegradable plastic–degrading enzyme, which degrades poly-butylene succinate and polybutylene succinate-co-adipate, was found in the strains of P. antarctica isolated from plant surfaces [10]. Further improvements for the commercial production of MELs, and their applications to life-science, nanotechnology and environmental technology, are currently in progress [15,16,17]
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