The Various Roles of Fatty Acids

Abstract

Lipids comprise a large group of chemically heterogeneous compounds. The majority have fatty acids (FA) as part of their structure, making these compounds suitable tools to examine processes raging from cellular to macroscopic levels of organization. Among the multiple roles of FA, they have structural functions as constituents of phospholipids which are the "building blocks" of cell membranes; as part of neutral lipids FA serve as storage materials in cells; and FA derivatives are involved in cell signalling. Studies on FA and their metabolism are important in numerous research fields, including biology, bacteriology, ecology, human nutrition and health. Specific FA and their ratios in cellular membranes may be used as biomarkers to enable the identification of organisms, to study adaptation of bacterial cells to toxic compounds and environmental conditions and to disclose food web connections. In this review, we discuss the various roles of FA in prokaryotes and eukaryotes and highlight the application of FA analysis to elucidate ecological mechanisms. We briefly describe FA synthesis; analyse the role of FA as modulators of cell membrane properties and FA ability to store and supply energy to cells; and inspect the role of polyunsaturated FA (PUFA) and the suitability of using FA as biomarkers of organisms.

Keywords: biomarkers; cellular membranes; fatty acid synthesis; glycerophospholipids; lipid bodies; lipidomics; membrane remodelling; omega-3 fatty acids; specialized lipids; storage lipids.

Figure 1

Accumulation of storage lipids in prokaryotes shown in Nile Red stained cells: PHA production in B. megaterium (a), C. necator (b) and S. aureus (c); TAG production in R. erythropolis (d); (de Carvalho and Caramujo, unpublished data).

Figure 2

(a) In temporary Mediterranean water ponds, Daphnia sp. feeds on bacteria, fungus and algae—algal material visible as green mass inside the gut; (b) FA of auto and heterotrophic origin are incorporated into the phospholipids of Daphnia, as shown by PLFA analysis (de Carvalho and Caramujo, unpublished data).