Microbial valorization of waste cooking oils for valuable compounds production a review

Waste cooking oils (WCO) are vegetable oils discarded after food frying and great amounts are produced worldwide. Its management is a challenge, due to the environmental risk of illegally disposal into rivers and landfills. The main approaches for WCO valorization included their incorporation as component of animal feed and biodiesel manufacturing. Yet, the development of new feasible approaches is attractive from an economic and ecological standpoint. Due to their composition in triglycerides, untreated WCO can be used as feedstock for microbial growth (several species are able to use them as carbon source) and production of added-value compounds. In this way, microbial valorization of WCO is a sustainable biotechnological approach to upgrade a waste into a renewable feedstock for bio-based industry, favoring the circular economy concept. The objective of this review is to highlight the potential use of WCO in bioprocesses as an alternative to other physicochemical treatments. Firstly, an introduction to WCO problematic is presented, describing most common applications used currently. Then, an extensive review on the use of WCO by microorganisms is shown, focusing on bacterial and fungi species and its exploitation for bioprocesses development to produce metabolites of industrial interest, such as biopolymers, biosurfactants, lipases and microbial lipids.This study was supported by the Portuguese Foundation for Science and Technology (FCT)under the scope of the project TUBITAK 2014 (TUBITAK/0009/2014), the strategic fund-ing of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope ofNorte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Biotechnological valorization of waste cooking oils: lipase and microbial lipids production by Yarrowia lipolytica

[Excerpt] Waste cooking oils (WCO) generated from vegetable oils used at high temperatures in food frying, cause environmental problems and must be reutilized. New strategies to valorize these wastes are attracting a great scientific interest due to the important advantages offered from an economic and environmental point of view. A microbial platform can be established to convert low-value hydrophobic substrates, such as waste cooking oils, to microbial lipids (single cell oil, SCO) and other value-added bioproducts, such as lipase. (...

Selection of yeast species for hydrocarbons and phenolic compounds degradation

[Excerpt] 1. Introduction. Large amounts of pollutant compounds are present in industrial effluents and, often, they are not totally degraded by physical and/or chemical methods before the discharge into the environment. Hydrocarbons and phenolic compounds are two examples of pollutants present in agro-industrial effluents, respectively in petroleum refinery effluents and olive mill wastewater (OMW). Biodegradation strategies involving microorganisms to simultaneously degrade these wastes and obtain high added-value products become an interesting approach, since the abundance of these compounds ensures the economic viability of bioprocesses while prevents major environmental problems. This work address the study of the ability of yeast species to grow on hydrocarbons and phenolic compounds as sole carbon and energy source. Moreover, the production of valuable compounds from these wastes was also assessed. [...]info:eu-repo/semantics/publishedVersio

Dissolved oxygen effect on microbial lipids production by Yarrowia lipolytica from volatile fatty acids

Volatile fatty acids (VFAs) can be obtained from organic wastes through acidogenic fermentation and the yeast Yarrowia lipolytica can use those VFAs for the biosynthesis of lipids. Oxygen is an important factor of the bioconversion process of VFAs into microbial lipids by Y. lipolytica, thus the effect of oxygenation was evaluated in batch cultures of the yeast for two different strains, varying the stirring and air flow rates. The increase of dissolved oxygen concentration improved lipid production by Y. lipolytica W29 and Y. lipolytica NCYC 2904 in glucose and VFAs (acetate, propionate and butyrate) medium. The strain NCYC 2904 accumulated higher intracellular lipids (22%, w/w) than strain W29 (12%, w/w) with differences in lipids composition. Lipids of strain W29 were mainly composed by linoleic acid (up to 47%) and oleic acid (up to 31%) and NCYC 2904 accumulated predominantly oleic acid (around 56%). For both strains, the unsaturated fraction (> 70%) exceeded the saturated one. Since fatty acid composition in Y. lipolytica are similar to common vegetable oils (usually used for biodiesel production), these lipids are a potential feedstock for biofuels production.Projects TUBITAK/0009/2014; UID/BIO/04469/2019, grant SFRH/BD/129592/2017. BioTecNorte (NORTE-01-0145-FEDER000004).info:eu-repo/semantics/publishedVersio

Bioconversion of volatile fatty acids into microbial lipids by Yarrowia lipolytica

Volatile fatty acids (VFAs) are short chain fatty acids that can be obtained from organic wastes through acidogenic fermentation and can be used as carbon source for microbial lipids production. The bioconversion of acetate, propionate and butyrate into microbial lipids by Yarrowia lipolytica W29 was evaluated, and the yeast shown the ability to grow using VFA as carbon source and accumulate lipids intracellularly (around 5 % of dry cell mass). The addition of a co-substrate (glucose or glycerol) to VFA-based medium led to an enhancement of cellular growth and lipid content of the cells. The highest lipids concentration of around 1 g/L was obtained in batch cultures carried out with a mixture of VFAs and glycerol. Notwithstanding the low lipid content obtained in this work, Y. lipolytica demonstrated the ability to metabolize VFAs and convert them to microbial lipids, which can be used for biodiesel production.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the project TÜBITAK 2014 (TUBITAK/0009/2014) and of the strategic funding of UID/BIO/04469 unit and COMPETE 2020 (POCI-01-0145-FEDER006684), Post-Doctoral grant (SFRH/BPD/101034/2014), Doctoral grant (SFRH/BD/129592/2017) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Yarrowia lipolytica is a promising oleaginous yeast for bio-oils production from volatile fatty acids

Every year, approximately 931 million tons of food waste (FW) are generated worldwide. The discharge of FW in the landfill has a negative environmental impact due to water and soil pollution and GHG emission. Volatile fatty acids (VFAs), produced by anaerobic fermentation of FW, can be used as a substrate by oleaginous yeasts to produce bio-oils. The bioconversion of pure VFAs into Y. lipolytica biomass and bio-oils was affected by oxygenation conditions in batch cultures carried out in a stirred-tank bioreactor. Approximately 3-fold enhancement in lipids concentration was obtained by increasing the agitation and aeration rates. Two-stage batch cultures (1st stage growth in glucose; 2nd stage bio-oils production in VFAs) proved to be an effective approach to improve lipids accumulation from pure VFAs. The highest lipid content was attained in conditions of dissolved oxygen concentration of 45% of saturation during the lipogenic phase. Y. lipolytica also accumulated lipids in food waste-derived VFAs, particularly in two-stage batch cultures (1st stage growth in VFAs; 2nd stage bio-oils production in crude glycerol). These bio-oils are promising feedstock for the biodiesel industry and the estimated fuel properties of biodiesel are in accordance with international standards.info:eu-repo/semantics/publishedVersio

Trick or Treat?

Funding Information: Funding: AC and FOM were supported by grants and contracts from the Portuguese Foundation for Science and Technology, PD/BD/136863/2018 and CEECIND/04266/2017, respectively.Accumulating evidence suggests the existence of a strong link between metabolic syndrome and neurodegeneration. Indeed, epidemiologic studies have described solid associations between metabolic syndrome and neurodegeneration, whereas animal models contributed for the clarification of the mechanistic underlying the complex relationships between these conditions, having the development of an insulin resistance state a pivotal role in this relationship. Herein, we review in a concise manner the association between metabolic syndrome and neurodegeneration. We start by providing concepts regarding the role of insulin and insulin signaling pathways as well as the pathophysiological mechanisms that are in the genesis of metabolic diseases. Then, we focus on the role of insulin in the brain, with special attention to its function in the regulation of brain glucose metabolism, feeding, and cognition. Moreover, we extensively report on the association between neurodegeneration and metabolic diseases, with a particular emphasis on the evidence observed in animal models of dysmetabolism induced by hypercaloric diets. We also debate on strategies to prevent and/or delay neurodegeneration through the normalization of whole-body glucose homeostasis, particularly via the modulation of the carotid bodies, organs known to be key in connecting the periphery with the brain.publishersversionpublishe

Yarrowia lipolytica as a cell factory to produce valuable compounds

Book of Abstracts of CEB Annual Meeting 2017Yarrowia lipolytica, a strictly aerobic yeast, with GRAS status, has an intense secretory activity and can metabolize a wide range of substrates that guaranteed a spot as an interesting industrial organism. Recently, food supplements derived from this yeast were approved for commercialization, which is particularly important for broadening the range of possible applications of the compounds produced by Y. lipolytica [1]. Within “Bioprocess Development and Optimization” research team, Y. lipolytica has been used as a cell model and exploited applying the biorefinery concept for the production of enzymes, microbial lipids, aroma and organic acids, using low-cost renewable substrates. A yeast-based integrated system was developed to valorize agro-industrial wastes, namely waste cooking oils and lard (used as a model of animal fat), by producing microbial lipids and lipase. The yeast oil content accumulated by Y. lipolytica from these inexpensive wastes was one of the higher ever reported for a non-genetically modified Yarrowia strain. Moreover, the simultaneous production of lipase may reduce the production cost of the microbial lipids and demonstrates that a biorefinery approach may be designed based on fat raw materials, allowing at the same time the reduction of fatty wastes surplus. Lipids accumulation on Y. lipolytica may also occur from non-oily substrates such as glucose or glycerol that can also lead to citric acid (CA) production under nitrogen-limitation conditions. Crude glycerol, byproduct from Biodiesel industry, has been used for CA production. Optimization of CA has been carried out by enhancing oxygen transfer rate at different types of bioreactors, such as STR, pressurized and airlift, as well as by mutagenesis strategies for strains improvement. Yarrowia lipolytica is a model microorganism for lipids metabolism. It can produce several compounds from fatty acids catabolism, mainly aromatic compounds, such as lactones. This species is able to transform ricinoleic acid into γ-decalactone, a peach-like aroma compound of great importance for flavoring industry. The production of γ-decalactone has been intensively studied in order to better understand all process and optimize it. The role of lipases in substrate hydrolysis, the effect of substrate concentration, dissolved oxygen concentration and different fermentation strategies - batch and stepwise fed-batch – and bioreactor designs (STR and airlift) in the γ-decalactone production was investigated [2]. The characterization of γ-decalactone production by genetic modified strains at labscale bioreactor was also performed. Yarrowia lipolytica potential to produce other aromatic compounds, such as 2-phenylethanol, is been now explored.info:eu-repo/semantics/publishedVersio

Simultaneous degradation of hydrocarbons and production of valuable compounds by Yarrowia lipolytica

Hydrocarbons are dangerous pollutants and great amounts of these compounds are released to the environment, due to the inadequate handling in the petroleum extraction or in the effluents of industries that use petroleum or its derivatives. The ability of Yarrowia lipolytica to efficiently degrade hydrocarbons (herein demonstrated with hexadecane and hexadecene) and use them as carbon source to grow and produce valuable compounds was demonstrated. In hexadecane-based medium, Y. lipolytica W29 cells were able to accumulate up to 16 % of their cellular dry weight as intracellular lipids. Due to its composition, similar to that of vegetable oils, these microbial lipids can be used as feedstock for biodiesel production. Moreover, the simultaneous production of lipase (2730 U·L-1), which market demand is increasing due to its application in the field of bioenergy, represents an economic advantage. Thus, it is possible to valorize wastes contaminated with hydrocarbons with this bioprocess.This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the project TÜBITAK 2014 (TUBITAK/0009/2014) and of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145- FEDER-006684), Post-Doctoral grant (SFRH/BPD/101034/2014) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020 – Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Lipofactory: Yarrowia lipolytica as a cell factory to produce microbial oils from hydrophobic substrates

Yarrowia lipolytica, an oleaginous yeast, is an adequate cell factory platform to convert low-value hydrophobic substrates into microbial oils and other important metabolites. The ability of Y. lipolytica W29 to produce microbial oils and other compounds (lipase and citric acid) from waste cooking oils (WCO) and animal fat (lard) was evaluated and the effect of several factors were assessed by an experimental design. OTR and pH was by far the most influential parameters for microbial oils production by Y. lipolytica W29 from lard and from WCO, respectively. Regardless of hydrophobic substrate used, the yeast oil content obtained (58% from lard and 53% from WCO) was one of the higher ever reported for a non-genetically modified Y. lipolytica strain. The unsaturated-to-saturated fatty acids ratio of these microbial oils is higher than in initial substrate, which indicates that they can be interesting as a potential source to food supplements. Besides intracellular lipids accumulation, a simultaneous production of lipase (from WCO) and citric acid and lipase (from lard) was observed, demonstrating that a biorefinery approach may be designed based on fat raw materials, allowing at the same time the reduction of fatty wastes surplus.info:eu-repo/semantics/publishedVersio