The metabolism and genetic regulation of lipids in the oleaginous yeast Yarrowia lipolytica

Yarrowia lipolytica biomass-a potential additive to boost metabolic and physiological responses of Nile tilapia

We studied the effects of Yarrowia lipolytica biomass on digestive enzymes, blood biochemical profile, energy metabolism enzymes, and proximate meat composition of Nile tilapias. The experiment was entirely randomized with four replications. The animals (n = 20 per repetition) were fed with 0%, 3%, 5%, and 7% of biomass for 40 days and then blood and liver were analyzed. There was an increase in the activities of chymotrypsin (5, 7% groups), trypsin (3, 5% groups), and sucrase (7% group) compared to the respective control groups. On the other hand, maltase activity was significantly reduced for all yeast biomass treatments, while the supplementation did not influence lipase and amylase activities. Moreover, the blood triacylglycerol concentrations were increased in the 7% group, while any treatment modified blood total cholesterol, glycemia, and hepatic glycogen content. Y. lipolytica biomass promoted significant increases in meat protein and lipid contents without changes in moisture and ash parameters. Furthermore, Y. lipolytica biomass promoted increases in hexokinase (3% group), phosphofructokinase (5, 7% groups), glucose-6-phosphate dehydrogenase (5% group), citrate synthase (3% group), aspartate aminotransferase and alanine aminotransferase (3% group), and glutamate dehydrogenase (3, 5% groups) compared to the respective control groups. At the same time, no changes were observed in the activity of glucose-6-phosphatase. Y. lipolytica biomass supplementation in tilapias' diet can modulate the digestive system and improve nutrient disponibility to the cells. Moreover, the changes in the metabolic profile and in energy metabolism can be correlated with the improvement of meat composition. Therefore, the Y. lipolytica biomass has a great potential to be used as a feed ingredient for Nile tilapias.

Microbial Lipid Based Biorefinery Concepts: A Review of Status and Prospects

The use of lignocellulosic biomass as a raw material for the production of lipids has gained increasing attention, especially in recent years when the use of food in the production of biofuels has become a current technology. Thus, the competition for raw materials for both uses has brought the need to create technological alternatives to reduce this competition that could generate a reduction in the volume of food offered and a consequent commercial increase in the value of food. Furthermore, the use of microbial oils has been studied in many industrial branches, from the generation of renewable energy to the obtainment of several value-added products in the pharmaceutical and food industries. Thus, this review provides an overview of the feasibility and challenges observed in the production of microbial lipids through the use of lignocellulosic biomass in a biorefinery. Topics covered include biorefining technology, the microbial oil market, oily microorganisms, mechanisms involved in lipid-producing microbial metabolism, strain development, processes, lignocellulosic lipids, technical drawbacks, and lipid recovery.

Using oils and fats to replace sugars as feedstocks for biomanufacturing: Challenges and opportunities for the yeast Yarrowia lipolytica

More than 200 million tons of plant oils and animal fats are produced annually worldwide from oil, crops, and the rendered animal fat industry. Triacylglycerol, an abundant energy-dense compound, is the major form of lipid in oils and fats. While oils or fats are very important raw materials and functional ingredients for food or related products, a significant portion is currently diverted to or recovered as waste. To significantly increase the value of waste oils or fats and expand their applications with a minimal environmental footprint, microbial biomanufacturing is presented as an effective strategy for adding value. Though both bacteria and yeast can be engineered to use oils or fats as the biomanufacturing feedstocks, the yeast Yarrowia lipolytica is presented as one of the most attractive platforms. Y. lipolytica is oleaginous, generally regarded as safe, demonstrated as a promising industrial producer, and has unique capabilities for efficient catabolism and bioconversion of lipid substrates. This review summarizes the major challenges and opportunities for Y. lipolytica as a new biomanufacturing platform for the production of value-added products from oils and fats. This review also discusses relevant cellular and metabolic engineering strategies such as fatty acid transport, fatty acid catabolism and bioconversion, redox balances and energy yield, cell morphology and stress response, and bioreaction engineering. Finally, this review highlights specific product classes including long-chain diacids, wax esters, terpenes, and carotenoids with unique synthesis opportunities from oils and fats in Y. lipolytica.

GATA-type transcriptional factor SpGAT1 interacts with SpMIG1 and promotes lipid accumulation in the oleaginous yeast [Formula: see text] zwy-2-3

BACKGROUND

In oleaginous yeast, nitrogen limitation is a critical parameter for lipid synthesis. GATA-family transcriptional factor GAT1, a member of the target of rapamycin (TOR) pathway and nitrogen catabolite repression (NCR), regulates nitrogen uptake and utilization. Therefore, it is significant to study the SpGAT1 regulatory mechanism of lipid metabolism for conversion of biomass to microbial oil in [Formula: see text] zwy-2-3.

RESULTS

Compared with WT, [Formula: see text], and OE::gat1, the lipid yield of OE::gat1 increased markedly in the low carbon and nitrogen ratio (C/N ratio) mediums, while the lipid yield and residual sugar of [Formula: see text] decreased in the high C/N ratio medium. According to yeast two-hybrid assays, SpGAT1 interacted with SpMIG1, and its deletion drastically lowered SpMIG1 expression on the high C/N ratio medium. MIG1 deletion has been found in earlier research to affect glucose metabolic capacity, resulting in a prolonged lag period. Therefore, we speculated that SpGAT1 influenced glucose consumption rate across SpMIG1. Based on yeast one-hybrid assays and qRT-PCR analyses, SpGAT1 regulated the glyoxylate cycle genes ICL1, ICL2, and pyruvate bypass pathway gene ACS, irrespective of the C/N ratio. SpGAT1 also could bind to the ACAT2 promoter in the low C/N medium and induce sterol ester (SE) accumulation.

CONCLUSION

Our findings indicated that SpGAT1 positively regulated lipid metabolism in S.podzolica zwy-2-3, but that its regulatory patterns varied depending on the C/N ratio. When the C/N ratio was high, SpGAT1 interacted with SpMIG1 to affect carbon absorption and utilization. SpGAT1 also stimulated lipid accumulation by regulating essential lipid anabolism genes. Our insights might spur more research into how nitrogen and carbon metabolism interact to regulate lipid metabolism.

Engineering Yarrowia lipolytica for the sustainable production of β-farnesene from waste oil feedstock

BACKGROUND

β-Farnesene is a sesquiterpene with versatile industrial applications. The production of β-farnesene from waste lipid feedstock is an attractive method for sustainable production and recycling waste oil. Yarrowia lipolytica is an unconventional oleaginous yeast, which can use lipid feedstock and has great potential to synthesize acetyl-CoA-derived chemicals.

RESULTS

In this study, we engineered Y. lipolytica to produce β-farnesene from lipid feedstock. To direct the flux of acetyl-CoA, which is generated from lipid β-oxidation, to β-farnesene synthesis, the mevalonate synthesis pathway was compartmentalized into peroxisomes. β-Farnesene production was then engineered by the protein engineering of β-farnesene synthase and pathway engineering. The regulation of lipid metabolism by enhancing β-oxidation and eliminating intracellular lipid synthesis was further performed to improve the β-farnesene synthesis. As a result, the final β-farnesene production with bio-engineering reached 35.2 g/L and 31.9 g/L using oleic acid and waste cooking oil, respectively, which are the highest β-farnesene titers reported in Y. lipolytica.

CONCLUSIONS

This study demonstrates that engineered Y. lipolytica could realize the sustainable production of value-added acetyl-CoA-derived chemicals from waste lipid feedstock.

Biomolecules from Plant Wastes Potentially Relevant in the Management of Irritable Bowel Syndrome and Co-Occurring Symptomatology

During and following the processing of a plant’s raw material, considerable amounts are wasted, composted, or redistributed in non-alimentary sectors for further use (for example, some forms of plant waste contribute to biofuel, bioethanol, or biomass production). However, many of these forms of waste still consist of critical bioactive compounds used in the food industry or medicine. Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders. The primary treatment is based on symptomatology alleviation and controlled dietary management. Thus, this review aimed to describe the possible relevance of molecules residing in plant waste that can be used to manage IBS and co-occurring symptoms. Significant evidence was found that many forms of fruit, vegetable, and medicinal plant waste could be the source of some molecules that could be used to treat or prevent stool consistency and frequency impairments and abdominal pain, these being the main IBS symptoms. While many of these molecules could be recovered from plant waste during or following primary processing, the studies suggested that enriched food could offer efficient valorization and prevent further changes in properties or stability. In this way, root, stem, straw, leaf, fruit, and vegetable pomaces were found to consist of biomolecules that could modulate intestinal permeability, pain perception, and overall gastrointestinal digestive processes.

Immunomodulatory effects of Yarrowia lipolytica as a food additive in the diet of Nile tilapia

The use of yeasts as a dietary additive for fish can act as a source of nutrients and as an immunostimulant. This work aimed to evaluate the effects of the fermented biomass of the yeast Yarrowia lipolytica as a food additive on zootechnical and hematological parameters, and on immune response in the plasma and kidney of Nile Tilapia (Oreochromis niloticus). After supplementation with 3, 5, and 7% of the yeast biomass for 35 days, the blood and tissues of the animals of each experimental group were collected for analysis. The addition of this biomass in the feed promoted an improvement of zootechnical parameters in tilapia. There was also a rise in the number of neutrophils (groups with 3, 5, and 7%) and monocytes (group 3, 5, and 7%) compared with the control group. Moreover, there was an increase in the levels of lysozyme, myeloperoxidase, and nitrite/nitrate content in the blood of animals fed with yeast biomass. On the other hand, there were no observed alterations in survival and hematological parameters of animals fed with yeast biomass. In the analysis of the kidney, the addition of biomass in feed promoted an increase in levels of myeloperoxidase (group with 3%) but did not alter the levels of lysozyme and nitrite/nitrate content. In conclusion, this study demonstrated that Y. lipolytica had growth and immunostimulatory effects on Nile tilapia. These findings strongly suggest the potential application of a Y. lipolytica-based immunostimulant for tilapia aquaculture.

A CRISPR/Cas9-Mediated, Homology-Independent Tool Developed for Targeted Genome Integration in Yarrowia lipolytica

Yarrowia lipolytica has been extensively used to produce essential chemicals and enzymes. As in most other eukaryotes, nonhomologous end joining (NHEJ) is the major repair pathway for DNA double-strand breaks in Y. lipolytica Although numerous studies have attempted to achieve targeted genome integration through homologous recombination (HR), this process requires the construction of homologous arms, which is time-consuming. This study aimed to develop a homology-independent and CRISPR/Cas9-mediated targeted genome integration tool in Y. lipolytica Through optimization of the cleavage efficiency of Cas9, targeted integration of a hyg fragment was achieved with 12.9% efficiency, which was further improved by manipulation of the fidelity of NHEJ repair, the cell cycle, and the integration sites. Thus, the targeted integration rate reached 55% through G₁ phase synchronization. This tool was successfully applied for the rapid verification of intronic promoters and iterative integration of four genes in the pathway for canthaxanthin biosynthesis. This homology-independent integration tool does not require homologous templates and selection markers and achieves one-step targeted genome integration of the 8,417-bp DNA fragment, potentially replacing current HR-dependent genome-editing methods for Y. lipolytica IMPORTANCE This study describes the development and optimization of a homology-independent targeted genome integration tool mediated by CRISPR/Cas9 in Yarrowia lipolytica This tool does not require the construction of homologous templates and can be used to rapidly verify genetic elements and to iteratively integrate multiple-gene pathways in Y. lipolytica This tool may serve as a potential supplement to current HR-dependent genome-editing methods for eukaryotes.

Recent advances in lipid metabolic engineering of oleaginous yeasts

With the increasing demand to develop a renewable and sustainable biolipid feedstock, several species of non-conventional oleaginous yeasts are being explored. Apart from the platform oleaginous yeast Yarrowia lipolytica, the understanding of metabolic pathway and, therefore, exploiting the engineering prospects of most of the oleaginous species are still in infancy. However, in the past few years, enormous efforts have been invested in Rhodotorula, Rhodosporidium, Lipomyces, Trichosporon, and Candida genera of yeasts among others, with the rapid advancement of engineering strategies, significant improvement in genetic tools and techniques, generation of extensive bioinformatics and omics data. In this review, we have collated these recent progresses to make a detailed and insightful summary of the major developments in metabolic engineering of the prominent oleaginous yeast species. Such a comprehensive overview would be a useful resource for future strain improvement and metabolic engineering studies for enhanced production of lipid and lipid-derived chemicals in oleaginous yeasts.

Sustainable Animal Feed Protein through the Cultivation of YARROWIA Lipolytica on Agro-Industrial Wastes and by-Products

Proteins are essential constituents of animal feeds, which comprise mainly vegetable protein (e.g., soybean meal), which is produced and transported globally. The decoupling of protein-production and livestock-growth areas results in protein deficiencies in certain parts of the world, and in significant environmental stress. Alternative, more sustainable protein feeds are necessary to meet the increasing needs, and to decrease the environmental footprint of animal products. Yeast Single Cell Proteins (SCP), produced locally using various agro-industrial by-product streams, have significant potential as alternative animal feed protein. Particularly, Yarrowia lipolytica, an oleaginous, non-pathogenic microorganism has been characterized as a “workhorse” in biotechnological studies, drawing the attention of many researchers. The present review summarizes available resources on critical issues concerning the applicability and commercialization of Yarrowia lipolytica as an environment-friendly protein source for animal feed. It discusses the sustainability of the yeast SCP production process, it presents the recent advances concerning Yarrowia lipolytica cultivation on low-cost agro-industrial by-products, and it stresses the effects on the health and welfare of productive animals due to the inclusion of Yarrowia lipolytica in their diet. The data presented in this study should facilitate relative research advancement and the commercialization of Yarrowia lipolytica’s use as an alternative protein source/supplement for animal feeds.

Soluble Sugar and Lipid Readjustments in the Yarrowia lipolytica Yeast at Various Temperatures and pH

Microorganisms cope with a wide range of environmental challenges using different mechanisms. Their ability to prosper at extreme ambient pH and high temperatures has been well reported, but the adaptation mechanism often remains unrevealed. In this study, we addressed the dynamics of lipid and sugar profiles upon different cultivation conditions. The results showed that the cells grown at various pH and optimal temperature contained mannitol as the major cytosol sugar alcohol. The elevated temperature of 38 °C led to a two- to three-fold increase in total cytosol sugars with concurrent substitution of mannitol for trehalose. Lipid composition in the cells at optimal temperature changed insignificantly at any pH tested. The increase in the temperature caused some drop in the storage and membrane lipid levels, remarkable changes in their composition, and the degree of unsaturated fatty acids. It was shown that the fatty acid composition of some membrane phospholipids varied considerably at changing pH and temperature values. The data showed a pivotal role and flexibility of the sugar and lipid composition of Y. lipolytica W29 in adaptation to unfavorable environmental conditions.