Aseptic production of citric and isocitric acid from crude glycerol by genetically modified Yarrowia lipolytica

• Published in: Bioresource technology 2019-01, Vol.271, p.340-344
• Main Authors: Rzechonek, Dorota A., Dobrowolski, Adam, Rymowicz, Waldemar, Mirończuk, Aleksandra M.
• Format: Article
• Language: English
• Subjects: Aseptic production; Citric acid; Citric Acid - metabolism; Crude glycerol; Glycerol - metabolism; Isocitrates - metabolism; Isocitric acid; Yarrowia - metabolism; Yarrowia lipolytica
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2018.09.118

•Overexpression of GUT1/GUT2 allow for aseptic production of organic acids.•Crude glycerol is a proper substrate for efficient isocitric acid production.•Aseptic conditions for organic acid synthesis were established. The unconventional yeast Yarrowia lipolytica is known for its capacity to produce citric or isocitric acid from glycerol. In this study a reduction of production cost was achieved by using cheap crude glycerol and conducting the production at pH 3 to prevent bacterial contamination. In this study a Y. lipolytica strain overexpressing Gut1 and Gut2 was used. For the modified strain, crude glycerol proved to be an excellent substrate for production of citric/isocitric acids in aseptic conditions, as the final concentration of these compounds reached 75.9 ± 1.8 g L−1 after 7 days of batch production. Interestingly, the concentration of isocitric acid was 42.5 ± 2.4 g L−1, which is one of the highest concentrations of isocitric acid obtained from a waste substrate. In summary, these data show that organic acids can be efficiently produced by the yeast Y. lipolytica from crude glycerol without any prior purification in aseptic conditions.