## 1 Introduction  
_Yarrowia lipolytica_, identified by [PERSON] in 1980, is an unconventional yeast species that is important in biotechnology due to its unique metabolic characteristics. [PERSON] and [PERSON] introduced the name _Yarrowia_, while the species _lipolytica_ reflects its ability to hydrolyse lipids [1]. It is often found in food products such as cheeses (Camembert, Livarot, and Rokpol), yoghurts, and sausages [2]. _Y. lipolytica_ is a non-pathogenic microorganism classified as GRAS (Generally Recognized as Safe) by the FDA [2]. It can, however, cause sporadic infections in critically ill and immunocompromised or patients who suffer prolonged hospitalisation [3]. The EFSA Panel evaluated _Y. lipolytica_ yeast biomass as a novel food under Regulation (EU) 2015/2283. The registered dried biomass contains 45-55 g/100 g protein, 25 g/100 g dietary fibre, and 7-10 g/100 g fat, primarily as beneficial monounsaturated and polyunsaturated fatty acids [4]. Still, these yeasts can accumulate lipids equivalent to 40% of their dry biomass. Under nutrient-limited conditions, lipid accumulation can reach values exceeding 70% of their biomass [5]. Its protein content is comparable to _S. cerevisiae_, and proteins from _Y. lipolytica_ yeast cells are also a source of micronutrients, including chromium and selenium in organic forms, which promotes their better absorption. _Y. lipolytica_ yeast has a high content of vitamins and minerals [6; 7; 8]. The yeast _Y. lipolytica_ efficiently metabolizes hydrophobic substrates, making it valuable for producing single-cell protein (SCP), single-cell oil (SCO), and citric acid. This yeast is an object of interest in research focusing on producing raw materials for biofuel synthesis and other industrial applications [9]. The current Commission Regulation (EU) 2024/2044 extends the possibility to use _Y. lipolytica_ yeast biomass as a novel food and sets maximum levels for its content in various food products. The biomass can be used among others, in food supplements (up to 6 g/ day for adults), meal replacements, foods for special medical purpose and a wide range of products such as beverages, dairy products, bread, sweets, snacks, and meat products, with specific limits ranging from a few grams to a few tens of grams per kilogram or litre [10]. Furthermore, only _Y. lipolytica_ biomass has been approved by EFSA as a novel food, while the microbial oil obtained from this biomass still remains largely unexplored and unregulated, with many studies highlighting its valuable properties. The microbial oil production process involves two main steps: biomass growth and lipid accumulation, followed by lipid extraction using solvents [11]. The yeast _Y. lipolytica_ stores fatty acids (FAs) in lipid bodies, primarily as triacylglycerolcels (TAGs) and sterol esters (SEs). Fatty acids are synthesized via two pathways: the de novo pathway, requiring hydrophilic substrates like sugars and organic acids to produce FAs from acetyl-CoA, and the ex novo pathway, which involves the hydrolysis of hydrophobic substrates such as alkanes and TAGs into FAs and glycerol for TAG synthesis [12]. Single-cell oil (SCO) can be generated through de novo pathways using glucose or other hydrophilic sources. When nitrogen is limited, it accumulates lipids early in the growth cycle, increasing its potential for industrial applications. Its rapid cell growth and high biomass density make it one of the most studied microbial bioproduct cell factories [13]. This oleaginous yeast can rapidly convert low-cost substrates into SCOs, making large-scale production possible despite high culture costs. Unlike plant and animal sources, microbial oil production is unaffected by seasonal or geographical factors [14]. SCOs are a sustainable source of polyunsaturated fatty acids (PUFAs) and can serve as an alternative to fish oils, which face issues likedeclining fish populations and contamination. Microbial production is resilient to climate change and offers high-purity oils [15].