The oleaginous yeast Lipomyces starkeyi is interesting for industrial-scale production of biodiesel. Here it is reported that this yeast is able to digest unsaccharified, soluble potato starch. In these experiments, the cultivation time of Lipomyces starkeyi was reduced to half of the previously reported values. The effect of C:N molar ratio was studied on growth and lipid content of L. starkeyi in media containing glucose or potato starch as C-source. At a C:N molar ratio of 61.2 in glucose medium, the lipid content was measured at 30 % of the dry matter. It was established that the cellular lipid content increased with increasing C:N molar ratio, but the cell yield decreased. In a pH-controlled 1-litre agitated and aerated bioreactor, batch cultivation on glucose resulted in 23 % lipids in cells on dry mass basis (dm), cell yield of 0.25 g/g glucose, and lipid yield of 0.06 g/g glucose. Under the same operating conditions, fed-batch cultivation with discrete glucose additions resulted in 27 % lipids, cell yield of 0.28 g/g glucose, and lipid yield of 0.08 g/g glucose. On soluble but unsaccharified sweet potato starch, cell yield was 0.41 g/g glucose equivalent, lipid yield 0.16 g/g glucose equivalent, and lipid content in cells 40 %. The major fatty acids in the cells were C16:0 and C18:1 (accounting for 85–90 % by mass of the total lipids) with the rest being C16:1 and C18:0. All of these are valuable lipids for biodiesel production. Based on these results, wastes and wastewater from food industry and sewage sludge could serve as sources for the production of biodiesel.

Kvasac Lipomyces starkeyi je zanimljiv za industrijsku proizvodnju biodizela, a dokazano je da može preraditi topljivi škrob iz krumpira. Stoga je uzgojen u pokusu, i to za upola kraće vrijeme nego u usporedbi s prethodnim ispitivanjima. Na podlozi je s glukozom ili škrobom iz krumpira, kao izvorima ugljika, ispitan utjecaj molarnog omjera C:N na rast L. starkeyi i udio lipida u kvascu. Udio je lipida u podlozi s glukozom, pri omjeru n(C):n(N)=61,2, iznosio 30 % suhe tvari. Utvrđeno je da se povećanjem C:N omjera povećava udio lipida u stanici, a smanjuje prinos stanica. Šaržnim su uzgojem na glukozi u bioreaktoru s miješalicom i prozračivanjem, volumena 1 L, te uz kontrolu pH-vrijednosti, dobivene ove vrijednosti: udio lipida u stanici od 23 % (na bazi suhe tvari), prinos stanica od 0,25 g suhe tvari/g glukoze i prinos lipida od 0,06 g/g glukoze. U istim je uvjetima šaržnim uzgojem s pritokom glukoze u malim obrocima dobiveno 27 % lipida, te postignut prinos stanica od 0,28 g suhe tvari/g glukoze i prinos lipida od 0,08 g/g glukoze. Uzgojem na podlozi s topljivim škrobom iz slatkog krumpira dobiven je prinos stanica od 0,41 g suhe tvari/g ekvivalenta glukoze, prinos lipida od 0,16 g/g ekvivalenta glukoze, te udio lipida u stanicama od 40 %. U stanicama su prevladavale C16:0 i C18:1 masne kiseline (85-90 % mase ukupnih lipida), a ostatak su bile C16:1 i C18:0 masne kiseline. Svi se ti lipidi mogu koristiti za proizvodnju biodizela. Rezultati upućuju na to da su otpad i otpadne vode iz prehrambene industrije te kanalizacijski mulj dobre sirovine za proizvodnju biodizela.