Yeasts, moulds, algae and bacteria as sources of lipids

Abstract

Microorganisms, which range from simple bacteria to the more complex filamentous fungi and include the autotrophic, photosynthesizing organisms of cyanobacteria and algae, produce a greater range of lipid types than either plants or animals. The lipids range from simple fatty acyllipids, such as the triacylglycerols, found in the other kingdoms, to unusual polyisopropenoid ether lipids found in bacteria growing at the extremes of environmental conditions. Such lipids have been little explored for their applications but it is known that they contribute considerably to the physiology of the cells that may live at temperatures of over 80°C, at low or high pH values or in hyper-saline environments. Bacteria also produce a lipid-soluble, polyester material, poly-β-hydroxybutyrate, not usually found in higher microorganisms and which is now of considerable commercial interest as a biodegradable plastic. (This is referred to later in section 9.6.) The entire field of microbial lipids has been the topic of a recent two-volume monograph (Ratledge and Wilkinson, 1988, 1989) and details of the lipids of most organisms that have been examined are contained therein.