Production of lipid from N‐acetylglucosamine by Cryptococcus curvatus

Abstract

N-Acetylglucosamine (GlcNAc), the monomeric constituent of chitin, is rarely used as a carbon source for fermentation technology. In this study, we demonstrate that the oleaginous yeast Cryptococcus curvatus ATCC 20509 can produce intracellular lipid during the cultivation process and total lipid content can reach 54% on a GlcNAc-based medium. Culture of C. curvatus under various conditions indicated that lipid accumulation also occurred at a relatively broad range of temperatures as well as relatively high initial GlcNAc concentrations. Fatty acid analysis indicated that the product was rich in palmitic acid, stearic acid, and oleic acid, closely resembling the composition of palm oil. More importantly, the lipid sample produced at 22 8C had a total saturated fatty acid content of 54.2 wt%, suggesting that it may be explored as cocoa-butter equivalent. Our data suggested that GlcNAc could be used as a feedstock for industrial biotechnology and that C. curvatus ATCC 20509 is a strain capable of accumulating high intracellular lipid using this nitrogen-rich renewable material.Practical applications: Microbial lipid is a versatile material, especially for biodiesel production. Stable and abundant renewable raw substrates remain to be explored for large-scale production of microbial lipid. The present work reports lipid production using N-acetylglucosamine (GlcNAc) by the oleaginous yeast Cryptococcus curvatus ATCC 20509 to yield up to 54% intracellular lipid content. More significantly, the lipid sample produced at 22 8C had a total saturated fatty acid content of 54.2 wt%, suggesting that it may be explored as cocoa-butter equivalent. Our technology provides the opportunity to effectively convert GlcNAc, available from one of the most abundant renewable materials chitin, into lipid. This procedure should prove valuable in terms of renewable energy production as well as environmental pollution control.

Microbial lipid production by Rhodosporidium toruloides under sulfate-limited conditions

“…In the literature, research efforts have been carried out to advance the total saturated fatty acid content of yeast lipid including extensive strain screening (Pan et al, 2009), inhibition of D9 and D12 desaturase (Moreton, 1985), chemical mutagenesis or genetic engineering of the oleaginous yeast Apiotrichum curvatum (Hassan et al, 1993;Ykema et al, 1989;Ykema et al, 1990), cultivation of A. curvatum on lowoxygenated media (Davies et al, 1990) and supplement of stearin, a cheap donor of stearic acid, into the culture of the yeast Yarrowia lipolytica (Papanikolaou et al, 2001;Papanikolaou et al, 2003). Very recently, we also found that lipid sample produced from Nacetylglucosamine by Cryptococcus curvatus ATCC 20,509 at 22°C was appropriate as CBE (Wu et al, 2010b). This work indicated the yeast R. toruloides Y4 was able to accumulate substantial Table 2 Conditions and results of lipid production by R. toruloides Y4 in cultures with a C/S molar ratio of 11,380 and various amounts of NH 4 Cl.…”

Lipids of oleaginous yeasts. Part II: Technology and potential applications

“…Moreover, yeasts can be cultured in various carbon sources including waste materials presenting simultaneously rapid and significant biomass and oil production. Likewise, the potential of several oleaginous yeasts to present efficient growth and lipid accumulation under nitrogenexcess conditions provided that another nutrient (e.g., phosphorus) is limited [29], can be exploited in industrial level for the valorization of agro-industrial residues and surpluses that are carbon-and nitrogen-rich, like media composed of Nacetylglucosamine [30] (it is known that this compound is the base-unit of chitin, whilst various chitin-based residues are currently generated in enormous quantities from crustaceanfabricating facilities and these wastes are disposed by either burning or land filling, both of which are harmful to the environment).…”

“…On the other hand, continuous cultures of A. curvatum at constant D and variations in the incubation temperature did not reveal noticeable differentiations in the composition of intra-cellular fatty acids produced [33]. Finally, in contrast with the results reported by Ferrante et al [135] and Granger et al [128], in batch shake-flask experiments performed by the yeast C. curvatus ATCC 20509 on N-acetyl-glucosamine utilized as the sole substrate, decrease of the incubation temperature (e.g., T ¼ 228C) was accompanied by synthesis of a fat that was remarkably enriched in saturated fatty acids (principally C16:0 and C18:0), in comparison with growth in higher temperatures (e.g., T ¼ 26-308C) [30].…”

“…The substrates used include analytical-grade or industrially derived sugars [15,23,25,29,[49][50][51][52][53][54][55][56][57][58][59], molasses [27,58,59], cheese whey [31,33,36,37,44,60], glucose-enriched tomato waste hydrolysate [61][62][63][64], glucose-enriched sewage sludge [24], polysaccharides [65][66][67], (raw) glycerol [45-47, 57, 68-73], glycerol-enriched tomato waste hydrolysate [64], prickly pear juice [74,75], N-acetyl-glucosamine [30], starch hydrolysates [76], inulin or Jerusalem artichoke hydrolysates [77][78][79], rice straw hydrolysates [48], sweet sorghum extracts [80], organic acids [51,[81][82][83]…”

Cocoa-Butter-Equivalent Production from <i>Yarrowia lipolytica</i> by Optimization of Fermentation Technology

“…Temperature adjustment could apply to somehow increase in SFA content and with the increase of cultivation temperature, the ratio of sum of saturated fatty acids was also increased. Wu et al (2010) reported that shift in the incubation temperature of Cryptococcus curvatus cultured on N-acetylglucosamine from 30 to 22°C, the content of cellular SFAs was significantly increased from 44 to 54% (w/w), while with the decrease of the temperature, it has no effect on the biomass and the product of Single Cell Oil (SCO). Rhodotorula glutinis produced twice unsaturated lipids at 15°C as much as that at 30°C (Beopoulos et al, 2009).…”