Physiological factors affecting total cell number and lipid content of the yeast, Lipomyces starkeyi.

Abstract

The effects of the concentration of the medium components and other cultural conditions on the total cell number and on the lipid content (mg of total lipid/108 cells) of the fat yeast Lipomyces starkeyi were examined. The no addition and deficiency of NH4+, K+, Mgt, P043-, SO42-, Zn2+, Fe3+, or Mn2+ decreased the total cell number. Mn2+ sufficiency increased the total cell number by a factor of 1.5 to 1.7, as compared with that of the standard concentration. The lipid content of the yeast was affected by six (NH4+, K+, Cat +, Zn2+, Fe3+, and Mn2+) ion concentrations. The no addition and deficiency of Zn2+ increased the lipid content by a factor ranging from 2.4 to 2.8 in comparison with that of the standard concentration. The concentration of Zn2+ also altered the lipid yield (g of lipid/100 g of glucose consumed) considerably. The concentration of Nat, Cl-, Cue, B033-, I-, Mo042-, and biotin had almost no effect on the total cell number, lipid content, and lipid yield of L. starkeyi. The cultural temperature and the initial pH value of the medium affected the total cell number and lipid content; the optimum temperature ranged from 25.5 to 29.5°C, and the optimum pH value was 4.9. A low concentration of dissolved oxygen decreased both the total cell number and lipid content. D-Glucose, D-mannose, D-galactose, Dlevulose, sucrose, D-xylose, and L-arabinose proved to be usable carbon sources for the growth and the lipid accumulation of L. starkeyi.Some yeasts accumulate a large amount of lipid in the cells. Although studies on lipid accumulation of microorganisms have been conducted since 1878, few reports on the physiological factors of lipid accumulation of yeasts have been published (1-4). The previous research conducted at our laboratory suggested that only a few trace elements affect the growth and the intracellular lipid (mainly 29

Phylogenetic and biochemical characterization of the oil-producing yeast Lipomyces starkeyi

“…The biomass increased to generate large lipid bodies. Different carbon sources have been shown to have varied influence on the lipid production of L. starkeyi (Naganuma et al 1985b). All strains converted D-glucose and D-mannose to lipids, but most rarely converted L-arabinose and D-cellobiose.…”

“…Several biochemical and physiological studies on this yeast have been performed, including the examination of the effects of media components, such as carbon sources, mineral ions, and culture temperature. These studies have shown that only a few trace elements influence the growth and lipid content of this yeast (Naganuma et al 1975(Naganuma et al , 1985a(Naganuma et al , 1985b1986;Suutari et al 1993;Zhao et al 2008). Moreover, it has been reported that some strains of this yeast converted not only glucose but also xylose to lipids (Fall et al 1984;Naganuma et al 1985b;Zhao et al 2008).…”

Microbial lipids from renewable resources: production and characterization

“…C/N ratio, pH, temperature and other environmental parameters Culture temperature and pH influence the total cell number and lipid content in yeast cells [151,17]. In minimal medium with glucose as carbon source, the yeast L. starkeyi accumulates large fractions of dry weight as lipids with a high yield in the pH range of 5.0-6.5 [10].…”

Using inorganic elements to control cell growth and lipid accumulation in Lipomyces starkeyi.

“…DISCUSSION The C/N ratio in a medium is well known as a potent factor for cell growth and lipid accumulation in fat-producing yeasts (10-13). Our studies showed that the concentration of inorganic micro-ions is a more potent factor than the C/N ratio, at least in cell growth and lipid accumulation in L. starkeyi (1,3,5,14). In the course of these studies, we frequently observed that the lipid accumulation of the yeast in a batch culture was governed by the progress of growth phases.…”