Candida tropicalis has recently emerged as a valuable yeast species with respect to lipid metabolism, not only for its oleaginous characteristics but also for its ability to utilize diverse range of substrates. Hence, it can be explored as an ideal host for lipid metabolic engineering, although inadequate genetic transformation system for developing the stable transformant has limited this scope. To resolve this existing constraint, we have come up with a novel strategy of a genomic integrating system in the oleaginous strain SY005 of C. tropicalis. Employing this system, comprising of host-specific regulatable promoter, transcription terminator, and integration locus, we have first examined the expression of a reporter gene, and then ectopically expressed a transcription factor CtRAP1 encoding the repressor activator protein 1 of C. tropicalis SY005. A maximum lipid content of 0.37 g/g dry cell weight was achieved in the engineered strain upon galactose induction, leading to 60% (w/w) increase relative to the wild type strain SY005. This work demonstrates the use of a markerless integrative transformation system to promote lipid accumulation in the diploid yeast without applying nutrient stress and hampering cell growth. The findings of this study will augment the research on lipid metabolic engineering and exploit the enormous potential of C. tropicalis as an industrial lipid feedstock. Key points •A transformation system was established in oleaginous yeast Candida tropicalis SY005 •Activity of host-specific molecular elements was verified by reporter gene expression •SY005 was engineered to ectopically express a transcriptional regulator gene CtRAP1 •The engineered strain exhibited 60% increase in lipid content on galactose induction •The increase in lipid content was correlated with the induced expression of CtRAP1.

中文翻译：

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工程化产油酵母热带念珠菌 SY005 以提高脂质生产。

热带念珠菌最近已成为脂质代谢方面有价值的酵母菌种，这不仅是因为其产油特性，还因为其能够利用多种底物。因此，它可以被探索为脂质代谢工程的理想宿主，尽管用于开发稳定转化体的遗传转化系统不足限制了这一范围。为了解决这个现有的限制，我们在热带假丝酵母产油菌株 SY005 中提出了一种基因组整合系统的新策略。利用这个由宿主特异性可调节启动子、转录终止子和整合位点组成的系统，我们首先检查了报告基因的表达，然后异位表达了编码 CtRAP1 的转录因子 CtRAP1。热带 SY005。在半乳糖诱导后，工程菌株中实现了 0.37 g/g 干细胞重量的最大脂质含量，导致相对于野生型菌株 SY005 增加了 60% (w/w)。这项工作证明了使用无标记整合转化系统来促进二倍体酵母中的脂质积累，而不施加营养压力和阻碍细胞生长。这项研究的结果将加强脂质代谢工程的研究，并利用热带假丝酵母作为工业脂质原料的巨大潜力。