Biotechnological production of γ-decalactone, a peach like aroma, by Yarrowia lipolytica

The request for new flavourings increases every year. Consumer perception that everything natural is better is causing an increase demand for natural aroma additives. Biotechnology has become a way to get natural products. γ-Decalactone is a peach-like aroma widely used in dairy products, beverages and others food industries. In more recent years, more and more studies and industrial processes were endorsed to cost-effect this compound production. One of the best-known methods to produce -decalactone is from ricinoleic acid catalyzed by Yarrowia lipolytica, a generally regarded as safe status yeast. As yet, several factors affecting -decalactone production remain to be fully understood and optimized. In this review, we focus on the aromatic compound -decalactone and its production by Y. lipolytica. The metabolic pathway of lactone production and degradation are addressed. Critical analysis of novel strategies of bioprocess engineering, metabolic and genetic engineering and other strategies for the enhancement of the aroma productivity are presented.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684)

Sugar versus fat: elimination of glycogen storage improves lipid accumulation in Yarrowia lipolytica

Triacylglycerol (TAG) and glycogen are the two major metabolites for carbon storage in most eukaryotic organisms. We investigated the glycogen metabolism of the oleaginous Y. lipolytica and found that this yeast accumulates up to 16% glycogen in its biomass. Assuming that elimination of glycogen synthesis would result in an improvement of lipid accumulation, we characterized and deleted the single gene coding for glycogen synthase, YlGSY1. The mutant was grown under lipogenic conditions with glucose and glycerol as substrates and we obtained up to 60% improvement in TAG accumulation compared to the wild type strain. Additionally, YlGSY1 was deleted in a background that was already engineered for high lipid accumulation. In this obese background, TAG accumulation was also further increased. The highest lipid content of 52% was found after 3 days of cultivation in nitrogen-limited glycerol medium. Furthermore, we constructed mutants of Y. lipolytica and S. cerevisiae that are deleted for both glycogen and TAG synthesis, demonstrating that the ability to store carbon is not essential. Overall, this work showed that glycogen synthesis is a competing pathway for TAG accumulation in oleaginous yeasts and that deletion of the glycogen synthase has beneficial effects on neutral lipid storage

Microbial oils as nutraceuticals and animal feeds

45 p.-5 fig.-3 tab.Lipids and oils are produced by all single-cell organisms for essential structural and functional roles; however, the term single cell oils (SCOs) is mainly restricted to describe the lipids produced by a limited number of oleaginous microorganisms (archaea, bacteria, yeast, fungi, and microalgae) with oil contents higher than 20% of biomass weigh. SCOs have different fatty acid compositions from those of plant seed or fish oils and are nowadays considered as new sources of nutraceuticals and animal feeds. In spite of the current commercial success of some SCOs, the development of more efficient microbial fermentation processes and the possibility of manipulating by systems metabolic engineering the lipid composition of cells require new biotechnological strategies to obtain high yields of the desired SCOs. Understanding the synthesis and regulatory mechanisms involved in the production of SCOs is fundamental to eliminate the metabolic bottlenecks that impair achieving high oil yields.This chapter is supported by grants from the Community of Madrid and the Structural Funds of the European Union (Ref: S2013/ABI2783 (INSPIRA1-CM)), the Ministry of Economy, the Industry and Competitiveness (Ref: RTC-2016-4860-2; Ref: BFU2014-55534-C2-1-P), and the Intramural Program of the CSIC (Ref: 201420E086) and the H2020 FET-OPEN program (LIAR: Ref 686585).Peer reviewe