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(1) Background: Odd-chain fatty acids (OCFAs) have garnered attention for their potential health benefits and unique roles in various biochemical pathways. Yarrowia lipolytica, a versatile yeast species, is increasingly studied for its capability to produce OCFAs under controlled genetic and environmental conditions. However, optimizing the synthesis of specific OCFAs, such as cis-9-heptadecenoic acid (C17:1), remains a challenge. (2) Methods: The gene coding for the Δ9 fatty acid desaturase, YlOLE1, and the gene coding the diacylglycerol O-acyltransferase 2, YlDGA2, were overexpressed in Y. lipolytica. With the engineered strain, the main goal was to fine-tune the production of OCFA-enriched lipids by optimizing the concentrations of sodium propionate and sodium acetate used as precursors for synthesizing odd- and even-chain fatty acids, respectively. (3) Results: In the strain overexpressing only YlDGA2, no significant changes in fatty acid composition or lipid content were observed compared to the control strain. However, in the strain overexpressing both genes, while no significant changes in lipid content were noted, a significant increase was observed in OCFA content. The optimal conditions for maximizing the cell density and the C17:1 content in lipids were found to be 2.23 g/L of sodium propionate and 17.48 g/L of sodium acetate. These conditions resulted in a cell density (optical density at 600 nm) of 19.5 ± 0.46 and a C17:1 content of 45.56% ± 1.29 in the culture medium after 168 h of fermentation. (4) Conclusions: By overexpressing the YlOLE1 gene and optimizing the concentrations of fatty acid precursors, it was possible to increase the content of OCFAs, mainly C17:1, in lipids synthesized by Y. lipolytica.

2-phenylethanol (2-PE) is a valuable aromatic alcohol with diverse applications in cosmetics, food, beverages, and pharmaceutical industries. Currently, 2-PE is produced either through chemical synthesis or by extraction from plant materials. However, both conventional production methods have their own limitations. Therefore, there is a need for more eco-friendly and cost-effective approaches to produce natural 2-PE. Biotechnological routes, particularly microbial fermentations, hold promise for natural 2-PE production, especially when using low-cost substrates. In this study, 2-PE was produced by de novo synthesis via the shikimate pathway, using the yeast Yarrowia lipolytica in a medium composed of sugar beet molasses (SBM) and yeast extract (YE) as carbon and nitrogen sources, respectively. A genetically engineered strain was generated, in which the SUC2 gene was transformed, expressing the invertase enzyme, enabling Y. lipolytica to efficiently utilize SBM as a cost-effective substrate. A central composite design allowed for the optimization of the concentrations of the carbon and nitrogen sources, resulting in approximately 0.71 g(2-PE)/L(culture medium). The results obtained highlight the potential of utilizing SBM as a low-cost substrate for 2-PE production, advancing biotechnological approaches in fragrance synthesis.

Colorimetric whole-cell biosensors are natural or genetically engineered microorganisms utilized to detect target molecules and ions as indicators of pollutants and biological activity in the environment. Upon detection, within specific concentration ranges which vary depending on the microorganism and its genetic circuitry among other factors, these sensors produce pigments which can be detected with the human eye past certain thresholds and quantified using simple analytical techniques, namely spectrophotometry. These sensors, which can be rendered portable through lyophilization and other methods, provide valuable and reliable substitutes of more demanding analytical ex situ techniques. The insights gained from this review can highlight technological progress in the field and contribute to the identification of potential opportunities afforded by these advancements.

Odd-chain fatty acids (OCFAs) have recently gained interest as target compounds in microbial production due to their diverse applications in the medical, pharmaceutical and chemical industries for the production of biofuels. Yarrowia lipolytica is a promising oleaginous yeast that has the ability to accumulate high quantities of fatty acids. However, the use of Y. lipolytica oils is still under research, in order to decrease the production costs related to the fermentation process and improve economic feasibility. In this work, sugar beet molasses (10–50 g/L) and crude glycerol (30 g/L) were used as the main carbon sources to reduce the processing costs of oil production from a genetically engineered Y. lipolytica strain. The effects of medium composition were studied on biomass production, lipid content, and OCFAs profile. Lipid production by yeast growing on molasses (20 g/L sucrose) and crude glycerol reached 4.63 ± 0.95 g/L of culture medium. OCFAs content represented 58% of the total fatty acids in lipids, which corresponds to ≈2.69 ± 0.03 g/L of culture medium. The fermentation was upscaled to 5 L bioreactors and fed-batch co-feeding increased OCFA accumulation in Y. lipolytica by 56% compared to batch cultures.

Odd-chain fatty acids (OCFA) have been studied for their therapeutic and nutritional properties, as well as for their potential use in the chemical industry for the production of biofuel. Genetic modification strategies have demonstrated an improved production of OCFA by oleaginous microorganisms. In this study, the production of OCFA-enriched lipids by fermentation using a genetically engineered Yarrowia lipolytica strain was investigated. The major fatty acid produced by this strain was the cis-9-heptadecenoic acid (C17:1). Its biosynthesis was optimized using a design of experiment strategy involving a central composite design. The optimal responses maximizing the cell density (optical density at 600 nm) and the C17:1 content (%) in lipids were found using 52.4 g/L sucrose, 26.9 g/L glycerol, 10.4 g/L sodium acetate, 5 g/L sodium propionate, and 4 g/L yeast extract. Under these conditions, in a 5 L scale bioreactor, the respective contents of lipids and C17:1 in culture medium were 2.52 ± 0.05 and 0.82 ± 0.01 g/L after 96 h fermentation. The results obtained in this work pave the way toward the process upscale of C17:1 and encourage its industrial production.

Brewers’ spent grains constitute a valuable byproduct of the beer industry. They are characterized by a rich nutritional composition consisting of around 70% lignocellulosic fibrous material, 20% proteins, 10% lipids, in addition to vitamins, minerals, amino acids, and phenolic compounds. These spent grains are produced in large amounts all through the year, are cheap, and lack economically feasible applications. Nowadays, 70% of these spent grains are used as animal feed, 10% are used for biogas production, and the remaining 20% are disposed in landfills. Due to the aforementioned facts, alternative uses of the brewers’ spent grains are highly sought-after. In fact, this nutrient-rich industrial by-product makes it a very good candidate for valorization through biotechnological processing, particularly microbial fermentation. After applying the needed pretreatments, using brewers’ spent grains as a substrate in submerged and solid-state fermentation of different microorganisms leads to the production of various value-added compounds such as organic acids, amino acids, volatile fatty acids, enzymes, vitamins, second-generation biofuels and other products.

The production of pigments using single cell microorganisms is gaining traction as a sustainable alternative to conventional syntheses, which rely, in no negligible proportions, on petrochemicals. In addition to depending on petroleum, these syntheses involved the use of toxic organic solvents, which may be inadequately disposed of across a range of industries, thus compounding the deleterious effects of fossil fuel exploitation. Literature suggests that notable research efforts in the area of sustainable pigment production using single cell microorganisms are focused on the production of pigments coveted for their interesting qualities, which transcend their mere capacity to dye various fabrics both natural and synthetic. As interest in sustainable pigment biosynthesis grows, the need to devise effective and efficient cell disruption processes becomes more pressing given that the viability of pigment biosynthesis is not only dependent on microorganisms’ yield in terms of production, but also on researchers’ ability to recover them. This review chiefly reports findings as to mechanical cell disruption methods, used individually or in various combinations, and their aptitude to recover biosynthetic pigments.

In the present research work, the physicochemical and fermentative properties of the “Ace spur” apple variety, obtained from a Lebanese farm, and the “Kermerrien” variety, obtained from a French cider industry, were investigated. The pomological properties were first determined for both varieties showing significant differences in the shapes and sizes. Sugar content, titratable acidity, soluble solids, and pH values were then determined. The potential of the “Ace spur” apple juice was then evaluated using the yeast strain Hanseniaspora sp., a major yeast found during the spontaneous fermentation of apples. “Ace spur” apples contained more sugars while the “Kermerrien” cultivar had a highest malic acid and polyphenol concentrations. After 100 h of fermentation, the ethanol percentage (v/v) was around 4% in both ciders. Results obtained in this work revealed the chemical potential of the Lebanese apple juice to produce cider.