Influence of cultivation conditions on lipid production by Cryptococcus albidus

Abstract

Cryptococcus albidus var. albidus CBS 4517 was able to accumulate lipid under nitrogen-limited as well as excess-nitrogen conditions. The highest lipid-producting capacity was, however, observed in nitrogen-limited cultivations. In nitrogen-limited batch cultures, a lipid content of 34% (w/w) in biomass and a maximum specific lipid productivity of 37 mg lipid/g lipid-free biomass·h, was determined. The yield of lipid from glucose was about 0.15 g/g in nitrogen-limited and 0.11 g/g in excess-nitrogen cultures. In a nitrogen-limited fed-batch culture, 12.4 g/l lipid was produced at 90 h of cultivation and the cells contained 46.3% (w/w) lipid. Higher lipid yield and cellular lipid content were observed when inorganic nitrogen sources were used compared with organic. The choice of carbon source was seen to influence growth as well as lipid production and the highest yields of lipid were obtained when glucose, maltose or mannitol was used. A cultivation temperature of 20°C provided the highest lipid productivity compared to 25°C and 30°C. Addition of citrate to the growth medium was seen to have a stimulating effect on the specific lipid productivity.