Triacylglycerol synthesis in the oleaginous yeastCandida curvata D

Abstract

Low rates of triacylglycerol (TAG) biosynthesis were observed in cell-free extracts of Candida curvata, but rates were increased up to 10-fold by adding either alpha- or beta-cyclodextrins. Spheroplasts, whole or gently disrupted, had higher rates of incorporation of both [U-14C]glycerol 3-phosphate or [1-14C]oleate into triacylglycerol and the intermediates of its biosynthesis: lysophosphatic acid, phosphatidic acid and diacylglycerol. Fatty acyl-CoA synthetase was highest with palmitate, oleate and linoleate but was some 6- to 8-fold lower with stearate. Stearate and stearoyl-CoA were poorly incorporated into lipids. Subcellular fractionation of the spheroplasts into mitochondrial, microsomal, lipid bodies and supernatant fractions diminished the rates of 14C incorporation of oleate into triacylglycerol. By comparing the relative specific activities for each activity in each fraction, the fatty acyl-CoA synthetase activity appeared mainly in the lipid bodies, and that for phosphatidic acid formation was mainly in the mitochondrion; other activities were too weak and too dispersed for accurate assessment of their location. Recombining all the subcellular fractions restored triacylglycerol synthesizing activity. Omitting any single fraction from the mixture did not result in restoration of triacylglycerol synthesizing activity. Starvation of the yeast, which leads to utilization of the endogenous lipid reserves, stimulated fatty acyl-CoA synthetase activity, but diminished phosphatidic acid and triacylglycerol biosynthesis indicating probable induction of beta-oxidation in the peroxisomes and repression of lipid biosynthesis.

Lipid formation in the oleaginous mould Entomophthora exitalis grown in continuous culture: effects of growth rate, temperature and dissolved oxygen tension on polyunsaturated fatty acids

“…They are not k n o w n to have a structural role in the cell and their function is limited to being a reserve storage material (Holdsworth and Ratledge 1991). T A G are present as discrete oil droplets within the cytoplasm.…”

Microbial‐based motor fuels: science and technology

“…While microorganisms do not typically make fatty acid methyl or ethyl esters, some microorganisms make copious amounts of storage lipids in the form of triacylglycerides and wax esters (Holdsworth and Ratledge, 1991; Kalscheuer et al., 2007). One bacterium, Acinetobacter baylyi strain ADP1, makes esters via an enzyme that catalyses acyltransfers to make wax esters and triacylglycerols and has very broad specificity with respect to the fatty acids and alcohols it binds (Kalscheuer and Steinbüchel, 2003).…”

Microbial lipid production from renewable and waste materials for second-generation biodiesel feedstock

“…A high C/N ratio of the culturing medium is required for oleaginous microorganisms to accumulate lipids. [40] Generally, ammonium ion (ammonium sulphate or ammonium chloride) is served as the deficit nutrient. It should be noted that nitrogen is not the only limiting nutrient for lipid synthesis; if nitrogen is present in excess, limitation of other nutrients can also induce lipid accumulation.…”