Citric acid production from glycerol-containing waste of biodiesel industry by Yarrowia lipolytica in batch, repeated batch, and cell recycle regimes

Yarrowia lipolytica A-101-1.22 produces high citric acid (112 g l(-1)) with a yield of 0.6 g g(-1) and a productivity of 0.71 g l(-1) h(-1) during batch cultivation in the medium with glycerol-containing waste of biodiesel industry. However, it was observed that the specific citric acid production rate, which was maximal at the beginning of the biosynthesis, gradually decreases in the late production phase and it makes continuation of the process over 100 h pointless. The cell recycle and the repeated batch regimes were performed as ways for prolongation of citric acid synthesis by yeast. Using cell recycle, the active citric acid biosynthesis (96-107 g l(-1)) with a yield of 0.64 g g(-1) and a productivity of 1.42 g l(-1) h(-1) was prolongated up to 300 h. Repeated batch culture remained stable for over 1000 h; the RB variant of 30% feed every 3 days showed the best results: 124.2 g l(-1) citric acid with a yield of 0.77 g g(-1) and a productivity of 0.85 g l(-1) h(-1).