ABSTRACT
Microorganisms were recognized as having similar oils to plants as long ago as 1878 (I), and the idea of using them as alternatives to plant oils was developed with some seriousness in Germany during both world wars ( 1914-18 and 193945) (2-4). Although no large-scale process was developed that played any significant nutritional role-the lipid-rich microbial mass that was produced was fed only to army horses-this early work established some important principles:
Lipid accumulation was encouraged by growing the microorganisms on a culture medium high in assimilatable carbon (usually glucose or sucrose) and low in nitrogen so that cells quickly exhausted the nitrogen supply
Balanced ~~~~h --.~ Lipogenic phase
0 10 20 Time(hours)
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F10. 1 Idealized diagram of process of lipid accumulation in an oleaginous microorganism. The culture medium is so formulated that N (usually as NH3) is exhausted after 20-30 hours, but the carbon source (e.g. glucose) remains in excess. This continues to be assimilated by the cells and is converted into lipid creating the "obese" microorganism.
