Growth yield, maintenance requirements, and lipid formation in the oleaginous yeast Apiotrichum curvatum.

For guiding and improving the efficiency of the production of lipid, complete insight into the flow of carbon and energy during growth and product formation is necessary. Therefore, data have been collected to determine various important growth parameters for the oleaginous yeast Apiotrichum curvatum. Chemostat experiments at specific growth rates, ranging from 0.05 to 0.15 h(-1) and recycling experiments with 100% biomass retention, with growth rates decreasing from 0.10 to 0.004 h(-1), demonstrated that maintenance requirements of A. curvatum are very low, compared to maintenance requirements described for other yeasts as Saccharomyces cerevisiae and Candida parapsilosis.It also appeared that growth and lipid production are proportional to substrate consumption when specific growth rates are higher than approximately 0.02 h(-1), but that lipid production stops at growth rates below this value. The practical consequences of these data are that fed batch cultures, which are often applied in fermentation industry, can only be useful with lipid producing yeasts when the growth rate in the process is carefully monitored to ensure specific growth rates higher than 0.02 h(-1). Dilution of the culture, partial recycling and/or a continuously increasing nutrient feed are solutions for the expected problems at low growth rates.