Aeration and Stirring in Yarrowia lipolytica Lipase Biosynthesis during Batch Cultures with Waste Fish Oil as a Carbon Source

Lipase Production by Limtongozyma siamensis, a Novel Lipase Producer and Lipid Accumulating Yeast

Lipase is a well-known and highly in-demand enzyme. During the last decade, several lipase optimization studies have been reported. However, production costs have always been a bottleneck for commercial-scale microbial enzyme production. This research aimed to optimize the conditions for lipase production by Limtongozyma siamensis DMKU-WBL1-3 via a One-Factor-At-a-Time (OFAT) approach combined with statistical methods while using a low-cost substrate. Results suggest that low-cost substrates can be substituted for all media components. An optimal medium was found, using response surface methodology (RSM) and central composite design (CCD), to consist of 0.50% (w/v) sweet whey, 0.40% (w/v) yeast extract (food grade), and 2.50% (v/v) palm oil with the medium pH adjusted to 4 under shaking flask cultivation. From an economic point of view, this work was successful in reducing production costs while increasing lipase productivity. The medium costs were reduced by 87.5% of the original cost while lipase activity was increased by nearly 6-fold. Moreover, lipase production was further studied in a 2-L stirred-tank fermentor. Its activity was 1,055.6 ± 0.0 U/ml when aeration and agitation rates were adjusted to 1 vvm and 170 rpm, respectively. Interestingly, under this optimal lipase production, the yeast showed accumulated lipids inside the cells. The primary fatty acid is a monounsaturated fatty acid (MUFA) that is typically linked to health benefits. This study hence reveals promising lipase production and lipid accumulation by L. siamensis DMKU-WBL1-3 that are worthy of further study.

Scale-up and fed-batch cultivation strategy for the enhanced co-production of microbial lipids and carotenoids using renewable waste feedstock

Agro-industrial by-product valorization as a feedstock for the bioproduction of high-value products has demonstrated a feasible alternative to handle the environmental impact of waste. Oleaginous yeasts are promising cell factories for the industrial production of lipids and carotenoids. Since oleaginous yeasts are aerobic microorganisms, studying the volumetric mass transfer (k_La) could facilitate the scale-up and operation of bioreactors to grant the industrial availability of biocompounds. Scale-up experiments were performed to assess the simultaneous production of lipids and carotenoids using the yeast Sporobolomyces roseus CFGU-S005 and comparing the yields in batch and fed-batch mode cultivation using agro-waste hydrolysate in a 7 L bench-top bioreactor. The results indicate that oxygen availability in the fermentation affected the simultaneous production of metabolites. The highest production of lipids (3.4 g/L) was attained using the k_La value of 22.44 h^-1, while higher carotenoid accumulation of 2.58 mg/L resulted when agitation speed was increased to 350 rpm (k_La 32.16 h^-1). The adapted fed-batch mode in the fermentation increased the production yields two times. The fatty acid profile was affected according to supplied aeration and after the fed-batch cultivation mode. This study showed the scale-up potential of the bioprocess using the strain S. roseus in the obtention of microbial oil and carotenoids by the valorization of agro-industrial byproducts as a carbon source.

Large-Scale Production of Isocitric Acid Using Yarrowia lipolytica Yeast with Further Down-Stream Purification

Isocitric acid (ICA) refers to a group of promising regulators of energy metabolism which has antistress, antihypoxic, and antioxidant activities. In this paper, we reported a process of ICA production from rapeseed oil using yeast Yarrowia lipolytica VKM Y-2373 in a 500-L fermentor. The producer synthesized 64.1 g/L ICA with a product yield of 0.72 g/g and a productivity 0.54 g/L·h. We also developed an effective purification method, including a cell separation, clarification, concentration, acidification, and crystallization process, which resulted in the formation of the crystals of monopotassium salt of ICA with a purity of 99.0–99.9%. To the best of our knowledge, this is the first report on an ICA production process at an upscaled bioreactor level.

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.

What makes Yarrowia lipolytica well suited for industry?

Yarrowia lipolytica possesses natural and engineered traits that make it a good host for the industrial bioproduction of chemicals, fuels, foods, and pharmaceuticals. In recent years, academic and industrial researchers have assessed its potential, developed synthetic biology techniques, improved its features, scaled its processes, and identified its limitations. Both publications and patents related to Y. lipolytica have shown a drastic increase during the past decade. Here, we discuss the characteristics of this yeast that make it suitable for industry and the remaining challenges for its wider use at large scale. We present evidence herein that shows the importance and potential of Y. lipolytica in bioproduction such that it may soon be one of the preferred choices of industry.

Use of Yarrowia lipolytica to Obtain Fish Waste Functional Hydrolysates Rich in Flavoring Compounds

Fishery processing industries generate large amounts of by-products. These by-products come from fish heads, skin, bones, thorns, and viscera. The disposal of these wastes represents an increasing environmental and health problem. Nowadays, there is a growing interest in how to utilize fish materials that are not used for human consumption. Among the different solutions proposed, the use of proteolytic and lipolytic microorganisms represents a green solution for waste valorization. In this work, first we screened several conventional and non-conventional microorganisms for their proteolytic and lipolytic functions. Then, the most promising strains (Yarrowia lipolytica YL2, Y. lipolytica YL4, Bacillus amyloliquefaciens B5M and B. subtilis B5C) were tested on a fish waste-based solution. After 72 h incubation at room temperature, the supernatants obtained using the strains of Y. lipolytica showed the highest degree of hydrolysis (10.03 and 11.80%, respectively, for YL2 and YL4), the strongest antioxidant activity (86.4% in DPPH assay for YL2) and the highest formation of aldehydes (above 50% of the total volatile compounds detected). Hydrolysates of fish waste obtained with Y. lipolytica may be reused in feed and food formulations for their functional and flavoring characteristics.

Production of pyruvic acid with Candida glabrata using self-fermenting spent yeast cell dry powder as a seed nitrogen source

Pyruvic acid is an important organic acid and a key industrial raw material. It is widely used in the chemical, agricultural, and food fields. Candida glabrata is the preferred strain for pyruvic acid production. The waste yeast cell for pyruvic acid fermentation with C. glabrata are rich in protein, amino acid, nucleic acid, and vitamins, as potential and cost-effective nitrogen source raw material. In this study, the potential of C. glabrata to produce pyruvic acid using spent yeast cell dry powder was evaluated. When 30 g/L of spray-dried spent yeast cell powder was used as the seed nitrogen source, a high titer of pyruvic acid was obtained. The pyruvic acid production reached 63.4 g/L with a yield of 0.59 g/g in a 5 L bioreactor. After scale-up to a 50 L bioreactor using the fermented spent yeast cell dry powder as a seed nitrogen source, 65.1 g/L of pyruvic acid was harvested, with a yield of 0.61 g/g. This study proposes a promisingapproach for increasing the pyruvic acid titer and reducing the costs.

Metabolome and Transcriptome Profiling Reveal Carbon Metabolic Flux Changes in Yarrowia lipolytica Cells to Rapamycin

Yarrowia lipolytica is an oleaginous yeast for the production of oleochemicals and biofuels. Nitrogen deficiency is beneficial to lipids biosynthesis in Y. lipolytica. Target of rapamycin (TOR) regulates the utilization of nutrients, which is inhibited in nitrogen starvation or by rapamycin treatment. However, under nitrogen-rich conditions, the lipids biosynthesis in Y. lipolytica after inhibition of TOR by rapamycin is elusive. Combining metabolomics and transcriptomics analysis, we found that rapamycin altered multiple metabolic processes of Y. lipolytica grown in nitrogen-rich medium, especially the metabolisms of amino acids and lipids. A total of 176 differentially accumulated metabolites were identified after rapamycin treatment. Rapamycin increased the levels of tryptophan, isoleucine, proline, serine, glutamine, histidine, lysine, arginine and glutamic acid, and decreased the levels of threonine, tyrosine and aspartic acid. Two fatty acids in lipid droplets, stearic acid (down-regulated) and stearidonic acid (up-regulated), were identified. The expression of 2224 genes changed significantly after rapamycin treatment. Further analysis revealed that rapamycin reduced carbon flux through lipids biosynthesis, accompanied by increased carbon flux through fatty acids degradation and amino acid (especially glutamic acid, glutamine, proline and arginine) biosynthesis. The dataset provided here is valuable for understanding the molecular mechanisms of amino acid and lipids metabolisms in oleaginous yeast.

Brine and Post-Frying Oil Management in the Fish Processing Industry—A Concept Based on Oleaginous Yeast Culture

Waste management solutions including the valorization of waste materials in biotechnological processes is an important issue needing to be explored. A significant amount of waste is being generated by the food industry. In this study, an attempt was made to utilize two fish industry wastes simultaneously—waste brine and post-frying oil from frying fish fillets in Yarrowia lipolytica culture with high single cell oil synthesis yield. Oxygenation in the culture medium had a positive effect on the biosynthesis efficiency of microbial oil, resulting in the highest content of lipids in yeast cells at the level of 0.431 g/g dm (dry mass). Y. lipolytica yeast preferentially accumulated oleic acid and linoleic acid, and the high content of linolenic acid, valuable from a nutritional point of view, was also found in microbial oil. This study proved that the use of post-frying rapeseed oil gives a chance to obtain valuable storage lipids in Y. lipolytica yeast cells via ex novo biosynthesis pathway. Furthermore, the wastewater stream could be limited using a waste brine as a solvent in medium preparation, but the brine share should not exceed 30% so as not to inhibit yeast cell growth.