Metabolic engineering of Yarrowia lipolytica for thermoresistance and enhanced erythritol productivity
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Biotechnology for Biofuels Open Access
RESEARCH
Metabolic engineering of Yarrowia lipolytica for thermoresistance and enhanced erythritol productivity Nan Wang1†, Ping Chi1†, Yawen Zou1†, Yirong Xu1, Shuo Xu1, M. Bilal2, Patrick Fickers3 and Hairong Cheng1*
Abstract Background: Functional sugar alcohols have been widely used in the food, medicine, and pharmaceutical industries for their unique properties. Among these, erythritol is a zero calories sweetener produced by the yeast Yarrowia lipolytica. However, in wild-type strains, erythritol is produced with low productivity and yield and only under high osmotic pressure together with other undesired polyols, such as mannitol or d-arabitol. The yeast is also able to catabolize erythritol in non-stressing conditions. Results: Herein, Y. lipolytica has been metabolically engineered to increase erythritol production titer, yield, and productivity from glucose. This consisted of the disruption of anabolic pathways for mannitol and d-arabitol together with the erythritol catabolic pathway. Genes ZWF1 and GND encoding, respectively, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were also constitutively expressed in regenerating the N ADPH2 consumed during erythritol synthesis. Finally, the gene RSP5 gene from Saccharomyces cerevisiae encoding ubiquitin ligase was overexpressed to improve cell thermoresistance. The resulting strain HCY118 is impaired in mannitol or d-arabitol production and erythritol consumption. It can grow well up to 35 °C and retain an efficient erythritol production capacity at 33 °C. The yield, production, and productivity reached 0.63 g/g, 190 g/L, and 1.97 g/L·h in 2-L flasks, and increased to 0.65 g/g, 196 g/L, and 2.51 g/L·h in 30-m3 fermentor, respectively, which has economical practical importance. Conclusion: The strategy developed herein yielded an engineered Y. lipolytica strain with enhanced thermoresistance and NADPH supply, resulting in a higher ability to produce erythritol, but not mannitol or d-arabitol from glucose. This is of interest for process development since it will reduce the cost of bioreactor cooling and erythritol purification. Keywords: Erythritol, Erythritol dehydrogenase, Mannitol dehydrogenase, Thermoresistance, Yarrowia lipolytica Background In industrialized countries, the overconsumption of sucrose and other specialties including honey, maple syrup, or high fructose corn syrup causes overweight, *Correspondence: [email protected] † Nan Wang, Ping Chi and Yawen Zou contributed equally to this work 1 State Key Laboratory of Microbial Metabolism, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China Full list of author information is available at the end of the article
obesity, diabetes, and metabolic syndrome [1, 2]. As an alternative sweetener, low or non-caloric molecules, such as sugar alcohol, are more and more considered. Among them, erythritol (1,2,3,4-butanetetrol) is a fourcarbon polyol with several exciting features. It has very low dig
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