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The study aimed to apply gamma radiation as a cell pretreatment method for lipid extraction and for obtaining astaxanthin from residual biomass of Haematococcus pluvialis. Factor 1 of the two-factor experimental design was represented by cell pretreatment methods: biomass with chloroform:methanol under ultrasound (BCMU), biomass with chloroform:methanol under γ radiation (BCMR), dry biomass under γ radiation (DBR), and control (without pretreatment). Factor 2 considered the vegetative and cystic phases. Cultivation was performed in a mixotrophic system, and biomass was collected in both phases, centrifuged, lyophilized, and submitted to cell pretreatment and lipid extraction. Lipid content and FAMEs were evaluated comparing pretreatment methods and life cycle phases. Total lipid content was higher with the BCMR method in the vegetative (18% DW) and cystic (14% DW) phases. Gamma radiation combined with organic solvent was more efficient for increasing lipid yield, and DBR had a lipid yield similar to BCMU. FAME content differed between phases and pretreatments for most fatty acids, mainly C16:0, C16:1, C18:1n9c, C18:2n6c, C18:2n6t, and C18:3n3. The predominance of saturated or low unsaturated fatty acids makes H. pluvialis, in both phases, suitable for biofuel production. The preservation of astaxanthin from residual cystic biomass was observed when submitted to the DBR method, with a concentration similar to the raw biomass (1.5% DW). Gamma radiation in dry biomass has an antioxidant effect. Therefore, the lipid extraction method preceded by gamma irradiation was efficient for vegetative and cystic cells of H. pluvialis and contributed to the preservation of astaxanthin from residual cystic biomass. [ABSTRACT FROM AUTHOR]

Industrial crops are becoming increasingly relevant as raw materials for different goods and services. Although there are many oilseed crops with industrial purposes, data about their production in Chile are scarce because the definition used by the Office of Agricultural Studies and Policies places agro‐industrial and industrial crops in the same category. Here, we review the available information about 12 industrial oleaginous crops at different levels of development (four native, two adventive and six introduced crops). Most of these crops have been evaluated for or are related to biodiesel production, despite the lack of commercial biodiesel production in Chile. Jojoba was the first industrial oilseed produced commercially in Chile; however, every year its production area decreases, and currently it does not exceed 100 ha. Sunflower and rapeseed, which are the first generation of raw materials for biodiesel production, have been poorly studied in Chile despite the large number of studies available on them worldwide. Camelina and castor bean have recently been studied; the former is produced in the south, while the latter is produced on the coastline in northern Chile. Further research is needed to improve the production and adaptation of these oilseed crops to climatic conditions in Chile; moreover, a new market must be opened to produce and commercialize their oils. Oilseed species native to Chile have not been extensively studied, and they represent an interesting option suitable for production under Chilean climatic conditions; this is particularly true for guindilla and chañar, because both can grow under different abiotic stresses. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Freshwater deficiency and growing requests for renewable energy have led to increased concern about water and energy security. Therefore, the present study attempted to evaluate the feasibility of using wastewater (WW) as a culture medium for microalgal cultivation with the aim of nutrient removal and biodiesel production. The green microalga Asterarcys quadricellulare (Chlorophyta) was isolated from a wastewater treatment plant in Menoufia, Egypt, and grown for 24 days in Bold's Basal Medium as a control and at different concentrations of secondary treated WW in distilled water (25%, 50%, 75%, and 100%). The results of 75% WW treatment recorded 96.6%, 98.4%, and 89.9% removal efficiency for nitrate, ammonia, and total phosphorus, respectively. Also, it revealed high biomass yield and biomass productivity (1.44 g L−1 and 69.0 mg L−1 day−1, respectively). In addition, it showed higher lipid production (360.6 mg L−1) and lipid productivity (17.2 mg L−1 day−1). Asterarcys quadricellulare fatty acid profile estimation revealed elevated proportions of oleic (54.92%), palmitic (20.54%), and linoleic acids (13.9%). Most of the properties of biodiesel derived from the studied microalga are consistent with those recommended by the international standards. The current study concluded that A. quadricellulare could be used for wastewater bioremediation and biomass production with high potential as biodiesel feedstock. [ABSTRACT FROM AUTHOR]

• Influence of phytohormones on algal biomass and lipid accumulation was investigated. • Auxin and cytokinin exihibited a synergystic effect on biomass and lipid yield. • Phytohormones influenced the activities of antioxidant enzymes SOD, CAT and APX. • Phytohormones modified the FAME contents that were desired for high-grade biofuels. Microalgae are considered as a promising resource for biodiesel. Nevertheless, their commercial exploitation necessitates considerable impetus towards the development of approaches for increased biomass and lipid production. The present work elucidates the impact of exogenously supplemented auxins, i.e., indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) and indole-3-propionic acid (IPA) and cytokinins, i.e., benzylaminopurine (BAP) and thidiazuron (TDZ) on biomass, lipid content and fatty acid profile of Desmodesmus sp. JS07. Among auxins, IBA improved the biomass and lipid content up to 1.96 ± 0.11 g/L and 34.88 ± 3.87 %, respectively while BAP among cytokinins increased the biomass and lipid content up to 1.88 ± 0.061 g/L and 31.84 ± 1.33 % respectively. Further, the cumulative impact of IBA (10 mg/L) and BAP (5 mg/L) resulted in their synergistic effect by stimulating biomass and lipid content up to 2.34 ± 0.032 g/L and 42.43 ± 1.88 % respectively. Auxins stimulated the superoxide dismutase activity, and cytokinins increased the enzymes (catalase and ascorbate peroxidase), scavenging reactive oxidative species, thereby regulating ROS homeostasis in microalgae. A significant alteration in the fatty acid profile owing to the type and dosage of phytohormones was detected. Hence, the strategy employing phytohormones could prove to be a meaningful approach for biofuel production. [ABSTRACT FROM AUTHOR]

Lipomyces starkeyi has been regarded as one of the model oleaginous yeasts. However, in this study, Lipomyces kononenkoae BF1S57 strain was found to be able to yield 60.06% (w/v) lipids (11.3 g/L lipids) from 90.0 g/L glucose, its cell mass was 18.8 ± 0.3 g/L within 96 h of a 10-L fermentation. Furthermore, the genome of L. kononenkoae has two copies of the genes encoding the β-subunit and α-subunit of fatty acid synthase, respectively. This may be related to high lipid contents in its cells. Over 94% of the fatty acids of the extracted lipids produced by L. kononenkoae BF1S57 strain was C 16:0 , C 16:1 , C 18:0 , C 18:1 and C 18:2 fatty acids. The properties of the prepared biodiesels in this study totally met the requirements of US biodiesel ASTM D6751 and EU biodiesel EN 14214. All these results demonstrated that the produced cellular lipids could be used as raw materials for biofuel production. • L. kononenkoae BF1S57 strain yielded 60.06% (w/v) lipids within 96 h of the 10-L fermentation. • Over 94% of the fatty acids of the extracted lipids was C 16:0 , C 16:1 , C 18:0 , C 18:1 and C 18:2 fatty acids. • The prepared fatty acid methyl esters could be used as biodiesels. [ABSTRACT FROM AUTHOR]

To elucidate the potential of Chlorococcum oleofaciens KF584224.1, the effects of different ferric ion concentrations (0, 10−7, 10−6, 10−5, 10−4 mol L−1) on growth, lipid accumulation, and fatty acid profile has been studied. The quantity and quality of extracted lipid was also analyzed by gravimetric and gas chromatographic methods, respectively, to evaluate their suitability according to the international standards for biodiesel (ASTM D6751 and EN 14214). An increase in ferric ion concentration up to 10−6 mol L−1 was associated with an increased specific growth rate by 1.83 folds and expanded exponential growth rate by 10 days compared with that in 0 mol L−1 ferric ion concentration. The highest biomass productivity (310.17 ± 2.19 mg L−1 d−1) and lipid productivity (138.81 ± 3.57 mg L−1 d−1) were achieved in culture medium supplemented with 10−6 and 10−5 mol L−1 ferric ion. The proportion of PUFAs and SFAs tends to decrease and increase by enhancing the ferric ion concentration, respectively. Although the quality of biodiesel produced form C. oleofaciens was found to be in accordance with the specifications in the American (ASTM D6751) and European (EN 14214) biodiesel standards, ferric ion supplementation enhanced the lipid characteristics obtained from C. oleofaciens for biodiesel production. • C. oleofaciens grew up 2.19-fold faster at 10−6 mol L−1 ferric ion concentration. • Maximum lipid productivity was obtained under 10−5 mol L−1 ferric ion concentration. • Enhancing in ferric ion supply played a positive role in SFAs accumulation. • The produced FAMEs met the biodiesel specifications of international standards. • Ferric ion concentration up to 10−5 mol L−1 improved the biodiesel quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • Studied effect of bacterial quorum sensing precursors (QSP) on algal lipidomic. • QSP promoted biomass (1.96–4.2X) and lipid productivity (2–4.5X) of Chlorella sp. • N-(3-Oxododecanoyl)-L-homoserine lactone increased biomass and neutral lipids. • N-(3-Hydroxyoctanoyl)-DL-homoserine lactone increased biomass and phospholipids. • QSP mediated oxidative stress coping mechanism and lipid accumulation of alga. Quorum sensing precursors of bacteria interact with microalgae in cultures and indirectly affect the algal physiology but their profound effect on the lipid and biomass in relation to improving the biofuel competence is one of the potential unexplored areas. The knowledge on the effect of phycospheric bacterial quorum sensing (QS) precursors on the lipid metabolism of microalgae under axenic and xenic conditions is highly restricted. This study endeavored to investigate an independent effect of QS precursors on the selected potential alga Chlorella sp. and unraveled the hidden prospect of QS for improvement of the lipids and identified the differences between the xenic and axenic conditions in the presence and absence of the QS precursors. Results revealed that N-(3-Oxododecanoyl)-L-homoserine lactone and N-(3-Hydroxyoctanoyl)-DL-homoserine lactone changed lipid composition, increased lipid productivity (2–4.5- folds) and biomass productivity (1.96–4.2- folds) under both xenic and axenic conditions of Chlorella sp. Further, selected QS precursors ameliorated fatty acid composition of the biomass that affected the resultant biodiesel properties at the end. N-(3-Hydroxyoctanoyl)-DL-homoserine promoted synthesis of PUFA and phospholipids with higher C18:2n6 compare to control. In contrast, N-(3-Oxododecanoyl)-L-homoserine lactone promoted SFA and neutral lipids with higher C18:00. Upon investigation of the stress physiology of Chlorella sp., it was revealed that the above QS precursors mediate the antioxidant levels and accumulate lipids, while also encourage biomass amelioration. [ABSTRACT FROM AUTHOR]

Acetate and ammonium were used as organic carbon and nitrogen sources, respectively, during mixotrophic cultivation of Chlorella pyrenoidosa . Cell growth, content of neutral lipid (NL), productivity of biomass and total lipid, and fatty acid profiles were investigated. Results showed that C. pyrenoidosa could endure high concentrations of NH 4 + -N (100–200 mg/L) and immediately entered logarithmic growth, when the culture media contained 2.0–10.0 g/L NaAc. The 2.0–10.0 g/L NaAc in the media also resulted in the NL content of 1.87–3.05 mg/10 9 cells, much higher than 0.5 mg/10 9 cells of the controls. The maximum productivities of biomass and total lipid were achieved under 50 and 10 mg/L NH 4 + -N respectively when the 2.0 g/L NaAc was dosed. The fatty acids were mainly composed of C16:0, C16:1, C18:0, and C18:1 under the mixotrophic cultivation, with the higher saturation compared to the controls. [ABSTRACT FROM AUTHOR]

Abstract: As promising alternatives to fossil‐derived oils, microbial lipids are important as industrial feedstocks for biofuels and oleochemicals. Our broad aim is to increase lipid content in oleaginous yeast through expression of lipid accumulation genes and use Saccharomyces cerevisiae to functionally assess genes obtained from oil‐producing plants and microalgae. Lipid accumulation genes DGAT (diacylglycerol acyltransferase), PDAT (phospholipid: diacylglycerol acyltransferase), and ROD1 (phosphatidylcholine: diacylglycerol choline‐phosphotransferase) were separately expressed in yeast and lipid production measured by fluorescence, solvent extraction, thin layer chromatography, and gas chromatography (GC) of fatty acid methyl esters. Expression of DGAT1 from Arabidopsis thaliana effectively increased total fatty acids by 1.81‐fold above control, and ROD1 led to increased unsaturated fatty acid content of yeast lipid. The functional assessment approach enabled the fast selection of candidate genes for metabolic engineering of yeast for production of lipid feedstocks. [ABSTRACT FROM AUTHOR]

In the present investigation, the application of NMR spectroscopic techniques was extensively used with an objective to explore the biodiesel potential of biomass cultivated on a lab scale using strains of Chlorella vulgaris and Scenedesmus ecornis. The effect of variation in the composition of culturing medium on the neutral and polar lipids productivity, and fatty acid profile of solvent extracts of microalgae biomass was studied. Determination of unsaturated fatty acid composition (C18:N = 1-3, ω3 C20:5, ω3 C22:6), polyunsaturated fatty esters (PUFEs), saturated fatty acids (SFAs), unsaturated fatty acids (UFAs), free fatty acids (FFAs), and iodine value were achieved from a single H NMR spectral analysis. The results were validated by C NMR and GC-MS analyses. It was demonstrated that newly developed methods based on H and C NMR techniques are direct, rapid, and convenient for monitoring the microalgae cultivation process for enhancement of lipid productivity and their quality aspects in the solvent extracts of microalgal biomasses without any sample treatment and prior separation compared to other methods. The fatty acid composition of algae extracts was found to be similar to vegetable and fish oils, mostly rich in C16:0, C18:N (N = 0 to 3), and n-3 omega polyunsaturated fatty acids (PUFAs). The lipid content, particularly neutral lipids, as well as most of the quality parameters were found to be medium specific by both the strains. The newly developed methods based on NMR and ultrasonic procedure developed for efficient extraction of neutral lipids are cost economic and can be an effective aid for rapid screening of algae strains for modulation of lipid productivity with desired biodiesel quality and value-added products including fatty acid profile. [ABSTRACT FROM AUTHOR]

Highlights: [•] Thermal hydrolysis–pyrolysis was used to produce hydrocarbon from inedible lipids. [•] Feedstock fatty acid composition did not influence organic liquid product yield. [•] Organic liquid product had compounds in the gasoline and diesel boiling range. [•] The organic liquid product mostly met the CGSB specification for diesel fuel. [ABSTRACT FROM AUTHOR]

Abstract: Rapid turnover of stored triacylglycerol occurs after seed germination, releasing fatty acids that provide carbon and energy for seedling establishment. Glycerolipid and fatty acid turnover that occurs at other times in the plant life cycle, including senescence is less studied. Although the entire pathway of β-oxidation is induced during senescence, Arabidopsis leaf fatty acids turnover at rates 50 fold lower than in seedlings. Major unknowns in lipid turnover include the identity of lipases responsible for degradation of the wide diversity of galactolipid, phospholipid, and other lipid class structures. Also unknown is the relative flux of the acetyl-CoA product of β-oxidation into alternative metabolic pathways. We present an overview of senescence-related glycerolipid turnover and discuss its function(s) and speculate about how it might be controlled to increase the energy density and nutritional content of crops. To better understand regulation of lipid turnover, we developed a database that compiles and plots transcript expression of lipid-related genes during natural leaf senescence of Arabidopsis. The database allowed identification of coordinated patterns of down-regulation of lipid biosynthesis genes and the contrasting groups of genes that increase, including 68 putative lipases. [Copyright &y& Elsevier]

Abstract: Quantification of total lipids is a necessity for any study of lipid production by microalgae, especially given the current interest in microalgal carbon capture and biofuels. In this study, we employed a simple yet sensitive method to indirectly measure the lipids in microalgae by measuring the fatty acids (FA) after saponification. The fatty acids were reacted with triethanolamine–copper salts (TEA–Cu) and the ternary TEA–Cu–FA complex was detected at 260nm using a UV–visible spectrometer without any colour developer. The results showed that this method could be used to analyse low levels of lipids in the range of nano-moles from as little as 1mL of microalgal culture. Furthermore, the structure of the TEA–Cu–FA complex and related reaction process are proposed to better understand this assay. There is no special instrument required and the method is very reproducible. To the best of our knowledge, this is the first report of the use of UV absorbance of copper salts with FA as a method to estimate lipids in algal cultures. It will pave the way for a more convenient assay of lipids in microalgae and can readily be expanded for estimating lipids in other biological systems. [Copyright &y& Elsevier]

A huge amount of a mixture of unreacted fatty acids and mono/di/triglycerides, namely bio-heavy oil, is generated as a waste from biodiesel industry. Considering that the lipid (i.e., triglycerides) accounts for 80% of the total biodiesel production cost, valorization of bio-heavy oil into biodiesel can be a viable route for enhancing the economic/environmental benefits. Nonetheless, the high contents of free fatty acids and impurities have restricted practical valorization of bio-heavy oil into biodiesel because conventional acid/base catalyzed transesterification suffers from the presence of the impurities. To overcome the technical challenge, this study suggested a direct valorization platform for the conversion of bio-heavy oil into biodiesel via thermally induced transesterification. Prior to biodiesel production, the properties of bio-heavy oil, such as acid value (105 mg KOH g−1 bio-heavy oil), its elemental compositions and thermal stability were characterized. Acid-catalyzed transesterification with a H 2 SO 4 catalyst showed the 31.1 wt% of biodiesel yield after 24 h of reaction at 60 °C. However, thermally induced transesterification exhibited 59.3 wt% of biodiesel yield after 1 min of reaction at 400 °C using a porous medium (SiO 2) with no presence of a catalyst. The porous SiO 2 (pore size: 6 nm) provided confined spaces for lipids and methanol, allowing the rapid transesterification reactions between them at high temperature. The biodiesel yield from thermally induced transesterification was proportionate to reaction temperature by 360 °C, but it decreased at > 400 °C due to the chemical bond scissions of unsaturated hydrocarbons. C 6-22 fatty acid methyl esters (FAMEs) were produced from thermally induced (non-catalytic) transesterifications, and weight fractions of each FAMEs were constant, regardless of the reaction conditions at ≤ 400 °C. All experimental findings offer a new recycle platform for BHO into biodiesel. [Display omitted] • Bio-heavy oil was converted into biodiesel via thermally induced reaction. • Thermally induced reaction doubled biodiesel yield (59%) than acid catalyzed one. • Thermally induced transesterification was tolerant to high contents of impurities. [ABSTRACT FROM AUTHOR]

Advancement of microalgae for use as biofuel feedstock depends on bioprospecting novel strains and then applying classical strain improvement techniques to enhance desirable traits. Here we successfully demonstrate this approach using two novel strains of green algae, identified as Desmodesmus armatus and Chlorella vulgaris, to improve biomass and lipid yields. UV irradiation was utilized to generate random mutations and the resulting populations were analyzed via flow cytometry to quantify lipid fluorescence while enriching for high lipid variants using fluorescence activated cell sorting. Secondary screening was performed via in situ fluorescence staining to identify the single highest lipid producing mutants from each strain. This approach produced a Desmodesmus armatus mutant that exhibited both increased biomass productivity and higher lipid content, which doubled lipid yield from the culture. The resulting Chlorella vulgaris mutant exhibited an increase in growth only, resulting in a 33% increase in lipid yield. • Generated novel UV-mutants of Desmodesmus armatus and Chlorella vulgaris. • Mutants displayed increased biomass and fatty acid productivities and yields. • Characterized growth and lipid composition of wild type and mutant strains. • Nile Red fluorescence did not consistently correlate with lipid content in mutants. [ABSTRACT FROM AUTHOR]