Similar growth rates, biomass accumulation, ammonium consumption, and pH values were observed when Y. lipolytica cells
were cultured in minimal medium with mixed substrate of
220 mM glycerol and 110 mM dextrose, compared with cultures
in minimal medium containing either 440 mM glycerol or
220 mM dextrose (Fig. 1f versus a and b). Slightly more neutral
lipid (approximately 38% dcw) was produced in the mixed substrate
cultures than the pure 440 mM glycerol in minimal media
(31% dcw) (Tables 1 and 2). Interestingly, Y. lipolytica displayed a
preference for consumption of glycerol over dextrose. A similar
substrate preference was reported with Y. lipolytica IBT 446, when
cultured with a mixture of glycerol and dextrose for sugar alcohol
synthesis, showing glycerol consumption favored over dextrose
(Workman et al., 2013). With Y. lipolytica ATCC 20460, a small
quantity of dextrose was utilized within the first 24 h, followed
by exclusive consumption of glycerol until it was completely
exhausted (Fig. 2e). Glycerol was consumed at 52 mM per day in
the minimal medium-mixed substrate cultures, which is similar
to the rate of consumption in the minimal medium-glycerol only
cultures