Simultaneous production of citric acid and invertase by Yarrowia lipolytica SUC+ transformants

Simultaneous production of citric acid (CA) and invertase by Yarrowia lipolytica A-101-B56-5 (SUC+ clone) growing from sucrose, mixture of glucose and fructose, glucose or glycerol was investigated. Among the tested substrates the highest concentration of CA was reached from glycerol (57.15 g/L) with high yield (YCA/S = 0.6 g/g). When sucrose was used, comparable amount of CA was secreted (45 g/L) with slightly higher yield (YCA/S = 0.643 g/g). In all cultures amount of isocitrate (ICA) was below 2% of total citrates. Considering invertase production, the best carbon source appeared to be sucrose (72 380 U/L). The highest yield of CA and invertase biosynthesis calculated for 1 g of biomass was obtained for cells growing from glycerol (9.9 g/g and 4325 U/g, respectively). Concentrates of extra- and intracellular invertase of the highest activity were obtained from sucrose as substrate (0.5 and 1.8 × 106 U/L, respectively).

► Simultaneous biosynthesis of invertase and citric acid was examined. ► Sucrose and glycerol were used as inexpensive carbon sources. ► High amount of invertase and citric acid was obtained regardless of carbon source. ► Yields and productivity of both metabolites were high. ► The process is waste-free and therefore cost-effective as well as environmentally friendly.