Enhancement of α-Ketoglutaric Acid Production by Yarrowia lipolytica Grown on Mixed Renewable Carbon Sources through Adjustment of Culture Conditions

Abstract

α-Ketoglutaric acid (KGA) is a valuable compound with a wide range of applications, e.g., in the cosmetics, pharmaceutical, chemical and food industries. The present study aimed to enhance the efficiency of KGA production by Yarrowia lipolytica CBS146773 from renewable carbon sources. In the investigation, various factors that may potentially affect KGA biosynthesis were examined in bioreactor cultures performed on a simple medium containing glycerol (20 g/L) and fed with four portions of a substrate mixture (15 + 15 g/L of glycerol and rapeseed oil). It was found that the process may be stimulated by regulation of the medium pH and aeration, application of selected neutralizing agents, supplementation with thiamine and addition of sorbitan monolaurate, whereas presence of biotin and iron ions had no positive effect on KGA biosynthesis. Adjustment of the parameters improved the process efficiency and allowed 82.4 g/L of KGA to be obtained, corresponding to productivity of 0.57 g/L h and yield of 0.59 g/g. In addition, the production of KGA was characterized by a low level (≤6.3 g/L) of by-products, i.e., citric and pyruvic acids. The results confirmed the high potential of renewable carbon sources (glycerol + rapeseed oil) for effective KGA biosynthesis by Yarrowia lipolytica.