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Using oleaginous microbial lipid-based biorefinery from lignocellulosic biomass (LCB) to produce fermentative bioenergy (i.e., biodiesel) represents an innovative second-generation fuel production technology. These lipids are predominantly intracellular triglycerides that accumulate through the metabolism of sugars in fermentation following pretreatment and enzymatic hydrolysis of LCB. This review investigates the recent advances in the microbial lipid production from LCB, focusing on the factors influencing the lead microbial lipid producers, different pretreatment methods (i.e., physical, chemical, biological, and combined pretreatment), enzymatic hydrolysis approaches, novel bioprocessing strategies (i.e., microbes-specific and fermentation model specific), and engineering techniques of the oleaginous microbes (i.e., genetic and metabolic alterations). The study demonstrates that oleaginous yeasts can synthesize significantly higher quantities of lipids when incorporated into the system, known as separated hydrolysis and lipid production, following various combined pretreatment methods. Interestingly, CRISPR is found to be the most suitable way of engineering microbes genetically and metabolically for increased lipid synthesis. The study also explores economically viable strategies for fermentative lipid production, addressing associated challenges, and outlines future directions, including comprehensive techno-economic and life cycle assessments. This review offers invaluable insights into microbial lipid production from LCB, highlighting the potential for significant technological and environmental enhancements through ongoing research and development efforts.

Using oleaginous microbial lipid-based biorefinery from lignocellulosic biomass (LCB) to produce fermentative bioenergy (i.e., biodiesel) represents an innovative second-generation fuel production technology. These lipids are predominantly intracellular triglycerides that accumulate through the metabolism of sugars in fermentation following pretreatment and enzymatic hydrolysis of LCB. This review investigates the recent advances in the microbial lipid production from LCB, focusing on the factors influencing the lead microbial lipid producers, different pretreatment methods (i.e., physical, chemical, biological, and combined pretreatment), enzymatic hydrolysis approaches, novel bioprocessing strategies (i.e., microbes-specific and fermentation model specific), and engineering techniques of the oleaginous microbes (i.e., genetic and metabolic alterations). The study demonstrates that oleaginous yeasts can synthesize significantly higher quantities of lipids when incorporated into the system, known as separated hydrolysis and lipid production, following various combined pretreatment methods. Interestingly, CRISPR is found to be the most suitable way of engineering microbes genetically and metabolically for increased lipid synthesis. The study also explores economically viable strategies for fermentative lipid production, addressing associated challenges, and outlines future directions, including comprehensive techno-economic and life cycle assessments. This review offers invaluable insights into microbial lipid production from LCB, highlighting the potential for significant technological and environmental enhancements through ongoing research and development efforts. [ABSTRACT FROM AUTHOR]

Bio-valorization approach of frying oil waste (FOW) to exploit it in different ways to produce added-value compounds is attractive from an economic and ecological standpoint. The aim of the current study was to investigate the incorporation of FOW in the fungal culture medium in order to develop feasible products such as single cell oils (SCOs), lipase, and citric acid (CA). According to response surface methodology (RSM), three independent variables have a significant effect on lipase and lipid accumulation by Lichtheimia corymbifera, namely, FOW amount (15 mL/L), ammonium sulfate concentration (5 g/L), and pH (6.0). The contour plots and 3D surface responses show the significant interaction of FOW amount and pH with ammonium sulfate concentration during lipase production. At these conditions, SCOs, lipase, and CA were produced with percentages 1.55 g/L, 54.3 U/mL, and 4.93 g/L, respectively. Fatty acid profile of the produced SCOs includes unsaturated fatty acids (USFAs) higher than saturated fatty acids (SFAs), which were 56.27 and 43.17% respectively. Furthermore, the dominant SFA is palmitic acid (29.22%), while the dominant USFA is oleic acid (30.78%). In conclusion, this study succeeded in valorization of FOW for SCOs, lipase, and CA in a one batch. [ABSTRACT FROM AUTHOR]

To combat the shortage of single agro-residue and overcome the problem of seasonal availability, it is beneficial to use mixture of lignocellulosic biomasses. In the present study, efforts were made to use mixed lignocellulosic biomass for production of bioethanol, along with microbial lipids and lactic acid. Upon enzymatic hydrolysis of mixed biomass at varied proportions it was observed that mixture of paddy straw and jute in the ratio 3:1 resulted in best sugar yield (41.50 g/L) at 10% substrate loading. Ethanolic fermentation of mixed substrate hydrolysate by thermotolerant yeast, Saccharomyces cerevisiae JRC6 resulted in 8.39 g/L of ethanol. To maintain sustainability and economic impact, oleaginous yeast (Trichosporon mycotoxinivorans S2) and lactic acid bacteria (Lactobacillus plantarum LP-9) were used for lipid production (14.5 g/L) and lactic acid production (11.08 g/L), respectively. Therefore, this study explored the potential of mixed lignocellulosic biomass to be exploited for production of various value-added products. [ABSTRACT FROM AUTHOR]

Mucoromycota are diverse in microbial oils, but oil-related studies have long been confined to a few particular genera and species. This study used the Sherlock Microbial Identification System to determine fatty acid compositions and consequently discover potential resources from 669 strains representing 133 species in 28 genera in 11 families from the core mucoromycotan orders Mortierellales, Mucorales, and Umbelopsidales. Results showed that 34% of strains, 50% of species, and 46% of genera were oleaginous. Eleven genera were proposed as oleaginous taxa for the first time. Among them, Backusella was highlighted in accumulating as high as 59.08 ± 2.24% of oils. Twenty-five and 50 strains were screened as potential high-yield fungi for oils and high-value fatty acids respectively. Pilaira produced the most C18:2, while Rhizopus and Thamnostylum produced the most C18:3. Only strains of Mortierella produced C20:4; Mo. amoeboidea CGMCC 3.15949 yielded 58.00% ± 1.15% of C20:4, which suggests it is an excellent source of C20:4. This study suggests for the first time that the bulk of Mucoromycota is rich in lipids. More genera and species were discovered herein as oil-producing resources. These findings serve as a foundation for further research on microbial oil production. [ABSTRACT FROM AUTHOR]

Oleaginous yeasts utilize renewable resources to produce lipids, which benefits sustainable development, and it is of great interest to screen robust lipid producers. Curvibasidium sp. belongs to nonconventional yeast that are very limitedly studied. Here, two cold-adaptive strains of Curvibasidium sp., namely, Y230 and Y231, isolated from the medicinal lichen Usnea diffracta were investigated for their potential in lipid production. Genome mining of Curvibasidium sp. Y231 was performed, and the special features related to fatty acid biosynthesis were revealed. Glucose, xylose, and glycerol were tested as sole carbon sources for yeast cell growth and lipid production. The total lipid contents of Curvibasidium sp. Y230 and Y231 range from 38.43% to 54.62% of the cell dry cell weight at 20°C, and glucose is the optimal carbon source. These results indicate that the Curvibasidium sp. strains are promising for sustainable lipid production. Our study provides basis for exploration of lichen-derived strains for biotechnological applications, and also benefits utilization of other nonconventional yeasts for sustainable production based on genome-based studies., (© The Author(s) 2023. Published by Oxford University Press on behalf of FEMS.)

Diverse health benefits are associated with dietary consumption of omega-3 long-chain polyunsaturated fatty acids (ω-3 LC-PUFA), particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Traditionally, these fatty acids have been obtained from fish oil, but limited supply, variably quality, and an inability to sustainably increase production for a rapidly growing market, are driving the quest for alternative sources. DHA derived from certain marine protists (heterotrophic thraustochytrids) already has an established history of commercial production for high-value dietary use, but is too expensive for use in aquaculture feeds, a much larger potential market for ω-3 LC-PUFA. Sustainable expansion of aquaculture is prevented by its current dependence on wild-caught fish oil as the source of ω-3 LC-PUFA nutrients required in the diet of aquacultured animals. Although several thraustochytrids have been shown to produce DHA and EPA, there is a particular interest in Schizochytrium spp. (now Aurantiochytrium spp.), as some of the better producers. The need for larger scale production has resulted in development of many strategies for improving productivity and production economics of ω-3 PUFA in Schizochytrium spp. Developments in fermentation technology and metabolic engineering for enhancing LC-PUFA production in Schizochytrium spp. are reviewed. [ABSTRACT FROM AUTHOR]