Oleaginous yeast Cryptococcus curvatus exhibits interplay between biosynthesis of intracellular sugars and lipids

Abstract

Patterns of the biosynthesis of major metabolites of the oleaginous yeast Cryptococcus curvatus NRRL Y-1511 were investigated during cultivation on sugar-based media. When lactose or sucrose was employed as substrate under nitrogen-limited conditions, the yeast strain accumulated high quantities of intra-cellular total sugars (ITS) at the beginning of fermentation (up to 68% w/w), with ITS values progressively decreasing to 20%, w/w, at the end of the fermentation. Decrease in ITS content and consumption of extracellular lactose led to a subsequent rise in lipid accumulation, reaching 29.8% in dry cell weight at 80 g/L of initial lactose concentration. Lactose was a more favorable substrate for lipid production than sucrose. In nitrogen-excess conditions, ITS were produced in significant quantities despite the continuous presence of nitrogen in the medium. Growth on lactose was not followed by secretion of extra-cellular b-galactosidase. High quantities of extra-cellular invertase were observed during growth on sucrose. The composition of ITS was highly influenced by the sugar used as substrate. Cellular lipids contained mainly palmitic and to lesser extent linoleic and stearic acids. This is the first report in the literature that demonstrates the interplay between the biosynthesis of intra-cellular total sugars and lipid synthesis for oleaginous yeast strains.Practical applications: Cryptococcus curvatus represents a promising candidate for the successful production of microbial lipids and polysaccharides during growth on several types of low-cost sugars utilized as substrates. Thus, C. curvatus could be used to produce a variety of metabolites useful for industrial biotechnology.

Effect of carbon and nitrogen source concentrations on the growth and lipid accumulation of yeastTrichosporon oleaginosusin continuous and batch culture

“…This phenomenon was observed at C:N ratio of 5.7 mol mol −1 and is in agreement with the increase of lipid‐free cell mass concentration in these conditions as well as CFU per cm 3 of media (Table ). Similar findings were reported for yeasts Cryptoccocus curvatus and Yarrowia lipolytica during batch cultivation in nitrogen‐excess and nitrogen‐limited media …”

Isolation, identification and screening of yeasts towards their ability to assimilate biodiesel‐derived crude glycerol: microbial production of polyols, endopolysaccharides and lipid

“…Naganishia uzbekistanensis FMCC Y 72 presented a clearly higher biomass and SCO production compared with the trial in which Gly 0 ≈40 g l −1 had been added into the medium, although again relatively increased Gly quantities (~50% w/w of the initial Gly added) remained unconsumed, even if the fermentation time had been significantly extended ( c. 18 days). Cryptococcus curvatus NRRL Y‐1511 presented a different physiological pattern compared with the previous micro‐organisms; at the earlier growth stages Gly assimilation led principally to the synthesis of IPS (and to lesser extent to cellular lipids) whereas further incubation increased the biosynthesis of cellular lipids, whereas endopolysaccharides values in both absolute (g l −1 ) and relative (%, w/w) values were reduced (there was an ‘interplay’ in the synthesis of these compounds; see also: Tchakouteu et al ). Moreover, the micro‐organism Debaryomyces sp.…”

Lipids from yeasts and fungi: physiology, production and analytical considerations

“…up to 68·1% w/w in DCW) were synthesized during growth of the relevant yeast strains during the first hours of the fermentation and in the significant presence of nitrogen into the medium (Tchakouteu et al . ). However, as cultivation proceeded, endopolysaccharides relative values were reduced to half, whereas in absolute values (g l −1 ) endopolysaccharides were mainly synthesized at the first growth steps, despite the significant presence of nitrogen into the medium.…”

“…Reduction of endopolysaccharides in DCW value was accompanied by a gradual increase in total cellular lipids in DCW values, suggesting “interplay” between the biosynthesis of intracellular polysaccharides and lipids (Tchakouteu et al . ). Similar physiological phenomena during which elevated endopolysaccharide quantities per unit of DCW have been reported at the first stages of the cultures performed under nitrogen‐limited conditions have been recorded for the oleaginous yeasts R. toruloides and Lipomyces starkeyi cultivated on waste glycerol (Tchakouteu et al .…”