Differences in enzyme activities of Lipomyces starkeyi between cells accumulating lipid and proliferating cells

Abstract

Differences in intracellular enzyme activities between cells accumulating lipid and proliferating cells were studied with Lipomyces starkeyi, a fat-producing yeast. When the cells were removed from a medium for lipid accumulation t o a medium for cell proliferation, activities of several enzymes on the glycolytic pathway, pentosephosphate cycle, glycerol 3-phosphate pathway, tricarboxylic acid cycle and fatty-acid biosynthesis pathway changed. In the proliferating cells, activities of glycerol-3-phosphate dehydrogenase (GDH) and ATP citrate lyase were very low, as compared to those in the cells accumulating lipids. Activities of these two enzymes and B-phospho- Further experiments provided a simple control method for the capabilities of the proliferation and lipid accumulation of L. sturkeyi (NAGANUMA et al. 1985a). Development of these methods enabled us to prove the relationship between the changes in capabilities of the yeast and intracellular enzyme activities. I n this report, differences of certain enzyme activities on the glycolytic pathway, pentosephosphate cycle, glycerol 3-phosphate pathway, trirarboxylic acid cycle and fatty-acid biosynthesis pathway in the proliferating cells and the cells accumulating lipid were studied. I n addition, the effects of zinc and manganese ions on enzyme activities were investigated. >laterials and methodsStrain and growth conditions: Lipomyces starkeyi IAM 4753 was grown at 29.5 "C, using a reciprocal shaker as described previously (UZUKA et al. 1974). The yeast was initially grown in a basal medium. As the basal medium, LS medium (glusose: 100 g/l) for enhancing lipid accumulation was used (NAGANUMA et al. 1985a). At 90 hr, the culture was divided into two parts and one was continuously shaken. I n another culture, 0.23 mM zinc ion (with ZnSO, . 7 H,O) and 0.40 mM manganese ion (with MnCI, . 4 H,O) were added to the basal medium to start proliferation.

Enzyme Activities in Oleaginous Yeasts Accumulating and Utilizing Exogenous or Endogenous Lipids

“…This is similar to the recent report by Naganuma et al (1987) for L. starkeyi that ACL activity was also high during lipid accumulation but greatly reduced during cell proliferation. ACL is inhibited by fatty acyl-CoA esters (Boulton & Ratledge, 1983a, b), which are the first breakdown products of triacylglycerol degradation; although this could bring about the rapid cessation of enzyme activity, on mixing of extracts from both types of cell (triolein grown and nitrogenlimited) the resultant specific activity was approximately half the individual activities.…”

Screening for <i>Lipomyces</i> strains with high ability to accumulate lipids from renewable resources

“…This result suggests that both the lipid-accumulation ability and the strength of the fat globule membrane could affect TAG recovery. The glycolytic pathway, pentose phosphate cycle, glycerol 3-phosphate pathway, tricarboxylic acid cycle, fattyacid biosynthesis pathway, and carbon uptake are involved in TAG biosynthesis in cells, and different enzymes regulate these pathways (Hübscher, 1970;Naganuma et al, 1987;Wakil, 1970). It is suggested that the high lipid accumulation is induced by the activation of these pathways Yeast strains corresponding to renewable resources as carbon sources.…”