Batch growth on both synthetic VFA and the
Batch growth on both synthetic VFA and the sterilized VFA stream from the P 22077 food-waste fermenter resulted in similar biomass concentration (p = 0.11, Table 3). However, the intracellular lipid concentration (14.9 ± 0.1%) and the maximum specific growth rate (0.021 ± 0.00 h−1) were statistically lower for fermentate VFA (p = 0.02, Table 3). Similarly, in a previous study, the oleaginous yeast C. curvatus also showed poor cell growth and a decrease in the intracellular lipid content (13.5%) when using food waste fermentation effluent as the growth medium ( Chi et al., 2011), pointing to the presence of as yet unknown inhibitors in the fermentate. Another possible cause of lower lipid yield could be the high protein content of the food waste, which can effectively lower the COD:N ratio below the favorable range (COD:N ? 25). Based on our previous results, food waste fermentate TKN concentrations were in the range 1410.8 ± 516.2 mg-N/L ( Ljupka Arsova, 2010) resulting in an effective feed COD:N ratio in our C. albidus batch cultures of 2.87:1. Although not attempted in nektonic organisms study, the observed differences in the kinetics (μm) and extent of lipid accumulation between synthetic VFA and VFA present in fermentate point to the necessity for independent optimization of lipid production from different waste streams, which is not entirely unexpected.