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The experimental results revealed that the 2.27-fold lipid yield was enhanced in nitrogen-depleted condition (226 mg/L) when compared to nitrogen rich condition (99.33 mg/L). Since specific growth rate (SGR) is the single most criteria to decide the biomass yield of microalgae, SGR was analyzed. SGR of 0.33 day −1 was observed with 0.47 doubling per day under nitrogen rich condition. However, low growth rate of 0.14 day −1 with a doubling of 0.20 per day was recorded under nitrogen depleted condition. In accordance with SGR, the dry biomass yield was ranged from 0.055 ± 0.005 to 1.394 ± 0.010 g/L in the presence of nitrogen, indicating the essentiality of major nutrient in the growth medium. The enhanced lipid accumulation under nitrogen starved condition by Scenedesmus quadricauda was perhaps achieved by adopting adverse environmental condition and possible increment in cell size in terms of length/breadth ratio (1.11). [ABSTRACT FROM AUTHOR]

Two fresh water microalgae, Coelastrella sp. M-60 and Micractinium sp. M-13 were investigated in this study for their potential of biodiesel production. For increasing biomass and lipid production, these microalgae were subjected to nutrient starvation (nitrogen, phosphorous, iron), salinity stress and nutrient supplementation with sugarcane industry effluent, citric acid, glucose and vitamin B 12 . The lipid productivity obtained from the isolates Coelastrella sp. M-60 (13.9 ± 0.4 mg/L/day) and Micractinium sp. M-13 (11.1 ± 0.2 mg/L/day) was maximum in salinity stress. The media supplemented with all the four nutrients yielded higher lipid productivity than the control. The response surface methodology (RSM) was employed to evaluate the effect of sugarcane industry effluent and citric acid on growth and lipid yield. Fatty acid profile of Coelastrella sp. M-60 and Micractinium sp. M-13 were composed of C-14, C-16:0, C-18:0, C-18:1 and C-18:2 and their fuel properties were also in accordance with international standards. [ABSTRACT FROM AUTHOR]

Simultaneous treatment (combining with cell disruption and lipid extraction) using hydrodynamic cavitation (HC) was applied to Nannochloropsis salina to demonstrate a simple and integrated way to produce oil from wet microalgae. A high lipid yield from the HC (25.9–99.0%) was observed compared with autoclave (16.2–66.5%) and ultrasonication (5.4–26.9%) in terms of the specific energy input (500–10,000 kJ/kg). The optimal conditions for the simultaneous treatment were established using a statistical approach. The efficiency of the simultaneous method was also demonstrated by comparing each separate treatment. The maximum lipid yield (predicted: 45.9% and experimental: 45.5%) was obtained using 0.89% sulfuric acid with a cavitation number of 1.17 for a reaction time of 25.05 min via response surface methodology. Considering its comparable extractability, energy-efficiency, and potential for scale-up, HC may be a promising method to achieve industrial-scale microalgae operation. [ABSTRACT FROM AUTHOR]

The growth, lipid production, and carbon use efficiency of two oleaginous yeasts, Rhodosporidium babjevae and Rhodosporidium diobovatum , were compared under nitrogen-limiting conditions with glycerol as the carbon source. Final biomass concentrations of R. babjevae and R. diobovatum were 9.4 ± 0.80 g/L and 12.0 ± 0.82 g/L, respectively, after 120 h of growth. Final lipid accumulation in for R. babjevae and R. diobovatum were 34.9 ± 3.0% cell dry weight (cdw) and 63.7 ± 4.5% cdw, respectively. Biomass production increased to 9.9 ± 0.2 g/L for R. babjevae and 14.1 ± 0.2 g/L for R. diobovatum in medium containing biodiesel-derived waste glycerol, but lipid accumulation decreased in both species. In a 7 L bioreactor with biodiesel-derived glycerol as carbon source, R. diobovatum produced 13.6 ± 0.4 g/L biomass and accumulated lipids to 50.7 ± 2.2% cdw, matching flask experiments. [ABSTRACT FROM AUTHOR]

The present work established an efficient staining method for fluorescence activated cell sorting (FACS) with Chlorococcum littorale maintaining cellular viability. The method was designed to detect high-lipid cells and to guarantee cellular viability. BODIPY 505/515 (BP) was more suitable to FACS when compared to Nile red. The optimum concentrations were 0.4 μg ml −1 of BP, 0.1% DMSO or 0.35% ethanol. Both ethanol and DMSO were equally efficient and assured cellular viability after the staining and sorting. Here a method is presented to rapidly screen and sort lipid rich cells of C. littorale with FACS, which can be used to produce new inoculum with increased cellular lipid content. [ABSTRACT FROM AUTHOR]

Microalgal biofilms grown to evaluate potential nutrient removal options for wastewaters and feedstock for biofuels production were studied to determine the influence of bicarbonate amendment on their growth, nutrient uptake capacity, and lipid accumulation after nitrogen starvation. No significant differences in growth rates, nutrient removal, or lipid accumulation were observed in the algal biofilms with or without bicarbonate amendment. The biofilms possibly did not experience carbon-limited conditions because of the large reservoir of dissolved inorganic carbon in the medium. However, an increase in photosynthetic rates was observed in algal biofilms amended with bicarbonate. The influence of bicarbonate on photosynthetic and respiration rates was especially noticeable in biofilms that experienced nitrogen stress. Medium nitrogen depletion was not a suitable stimulant for lipid production in the algal biofilms and as such, focus should be directed toward optimizing growth and biomass productivities to compensate for the low lipid yields and increase nutrient uptake. [ABSTRACT FROM AUTHOR]

In this research, a two-stage process consisting of cultivation in nutrient rich and nitrogen starvation conditions was employed to enhance lipid production in Chlorella vulgaris algal biomass. The effect of supplying different organic and inorganic carbon sources on cultivation behavior was investigated. During nutrient sufficient condition (stage I), the highest biomass productivity of 0.158 ± 0.011 g/L/d was achieved by using sodium bicarbonate followed by 0.130 ± 0.013, 0.111 ± 0.005 and 0.098 ± 0.003 g/L/d for sodium acetate, carbon dioxide and molasses, respectively. Cultivation under nitrogen starvation process (stage II) indicated that the lipid and fatty acid content increased continuously to a maximum value at day 2. Using carbon dioxide resulted in highest cell density, while using sodium acetate led to the highest fatty acid content. Molasses was not as effective as other carbon sources, but by taking into account its lower price, it can be considered as a suitable carbon source for algal lipid productivity. [ABSTRACT FROM AUTHOR]

Microalgae have attracted growing attention due to their potential in biofuel feedstock production. However, current understanding of the regulatory mechanisms for lipid biosynthesis and storage in microalgae is still limited. This study revealed that the microalga Chlorella sorokiniana showed sequential accumulation of starch and lipids. When nitrogen was replete and/or depleted over a short period, starch was the predominant carbon storage form with basal levels of lipid accumulation. After prolonged nitrogen depletion, lipid accumulation increased considerably, which was partially due to starch degradation, as well as the turnover of primary metabolites. Lipid accumulation is also strongly dependent on the linear electron flow of photosynthesis, peaking at lower light intensities. Collectively, this study reveals a relatively clear regulation pattern of starch and lipid accumulation that is basically controlled by nitrogen levels. The mixotrophic growth of C. sorokiniana shows promise for biofuel production in terms of lipid accumulation in the final biomass. [ABSTRACT FROM AUTHOR]

The effects of fluctuating intensity of solar radiation on biomass and lipid in oleaginous microalgae are important. However, this topic has not been the subject of studies for a long time. In this study, four oleaginous microalgae from semi-arid areas were screened and cultivated outdoors under different fluctuating intensities. Results showed that the highest lipid productivities and neutral lipid (NL) contents occurred under high fluctuating intensity (HFI), in which 13–20% of the increased NL came from glycolipid transformation without phospholipid conversion. Chlorella sp. L1 and Monoraphidium dybowskii Y2 obtained from biological soil crusts in desert had the largest biomass (137.13, 106.61 mg L −1 d −1 ) and lipid yields (35.06, 32.45 mg L −1 d −1 ) under HFI. The highest areal lipid productivities of 9.06 and 8.95 g m −2 d −1 and better biodiesel quality were observed under HFI. Accordingly, sufficiently adopting fluctuating light intensity outdoors to culture microalgae was an economic and effective approach. [ABSTRACT FROM AUTHOR]

Nannochloropsis has emerged as a promising alga for biodiesel production. However, the genus consists of 6 species and hundreds of strains making strain selection a challenge. Furthermore, oil productivity is instrumental to economic viability of any algal strain for industrial production, which is dependent on growth rate and oil content. In most cases, these two parameters have been studied independently. Thus, the goal of this study is to provide a combined method for evaluating strain performance in specially designed photobioreactors together with an in-depth lipidomic analyses. The nine strains of Nannochloropsis tested showed considerable variations in productivity and lipidomics highlighting the importance of strain selection. Finally, Nannochloropsis gaditana CCMP527 and Nannochloropsis salina CCMP537 emerged as the two most promising strains, with an oil content of 37 and 27 dry wt% after 11-day nitrogen starvation, respectively, resulting in TAG productivity of 13 × 10 −3 and 18 × 10 −3 kg m −3 d −1 , respectively. [ABSTRACT FROM AUTHOR]

Biodiesel with improved yield was produced from microalgae biomass under simultaneous cooling and microwave heating (SCMH). Nannochloropsis sp. and Tetraselmis sp. which were known to contain higher lipid species were used. The yield obtained using this novel technique was compared with the conventional heating (CH) and microwave heating (MWH) as the control method. The results revealed that the yields obtained using the novel SCMH were higher; Nannochloropsis sp. (83.33%) and Tetraselmis sp. (77.14%) than the control methods. Maximum yields were obtained using SCMH when the microwave was set at 50 °C, 800 W, 16 h of reaction with simultaneous cooling at 15 °C; and water content and lipid to methanol ratio in reaction mixture was kept to 0 and 1:12 respectively. GC analysis depicted that the biodiesel produced from this technique has lower carbon components (<19 C) and has both reasonable CN and IV reflecting good ignition and lubricating properties. [ABSTRACT FROM AUTHOR]

Chloroform and methanol are superior solvents for lipid extraction from photosynthetic microorganisms, because they can overcome the resistance offered by the cell walls and membranes, but they are too toxic and expensive to use for large-scale fuel production. Biomass from the photosynthetic microalga Scenedesmus , subjected to a commercially available pre-treatment technology called Focused-Pulsed® (FP), yielded 3.1-fold more crude lipid and fatty acid methyl ester (FAME) after extraction with a range of solvents. FP treatment increased the FAME-to-crude-lipid ratio for all solvents, which means that the extraction of non-lipid materials was minimized, while the FAME profile itself was unchanged compared to the control. FP treatment also made it possible to use only a small proportion of chloroform and methanol, along with isopropanol, to obtain equivalent yields of lipid and FAME as with 100% chloroform plus methanol. [ABSTRACT FROM AUTHOR]

In this study, the culture medium components screening and filtering were undertaken in order to set up efficient and cost effective minimal culture media for lipid production from Yarrowia lipolytica DSM3286. The basal minimal culture medium (S2) designed yielded lipid content up to 35% of the microbial dry cell weight. A set of fermentation strategies based on this minimal medium was developed and the lipid content was raised to 51%. The scale-up under different fermentation conditions based on S2 medium led to a maximum lipid content of 65%. The produced microbial oils displayed interesting properties to be used as a feedstock for high quality biodiesel production. The minimal media and operable cultivation strategies devised in this study, in association with the works done so far by other authors, could enable fast, massive, viable and more economical production of single cell oils and smooth biodiesel manufacture. [ABSTRACT FROM AUTHOR]

The study explores on upstream and downstream process in Microcystis aeruginosa for biodiesel production. The alga was isolated from temple tank, acclimatized and successfully mass cultivated in open raceway pond at semi-continuous mode. A two step combined process was designed and harvested 99.3% of biomass, the daily dry biomass productivity was recorded up to 28 g m –2 day −1 . The lipid extraction was optimized and achieved 21.3%; physicochemical properties were characterized and found 11.7% of FFA, iodine value 72% and 99.2% of ester content. The lipid was transesterified by a two step simultaneous process and produced 90.1% of biodiesel; the calorific value of the biodiesel was 38.8 MJ/kg. Further, the physicochemical properties of biodiesel was characterized and found to be within the limits of American ASTM D6751. Based on the areal and volumetric biomass productivity estimation, M. aeruginosa can yield 84.1 tons of dry biomass ha −1 year −1 . [ABSTRACT FROM AUTHOR]

The types of microalgae strains and the method used in lipid extraction have become crucial factors which influence the productivity of crude oil. In this paper, Nannochloropsis sp. and Tetraselmis sp. were chosen as the strains and four different methods were used to extract the lipids: Hara and Radin, Folch, Chen and Bligh and Dyer. These methods were performed by using conventional heating and microwave irradiation methods. Results revealed that highest lipid yield from the different species was obtained using different extraction methods; both under microwave irradiation. The lipid yield for Tetraselmis sp. and Nannochloropsis sp. was highest when Hara and Radin (8.19%), and Folch (8.47%) methods were used respectively under microwave irradiation. The lipids extracted were then transesterified to biodiesel and the quality of the biodiesel was analyzed using the gas chromatography. [ABSTRACT FROM AUTHOR]

Supplementing proper nutrients could be a strategy for enhancing algal biomass, nutrients uptake and lipid accumulation in the coupling system of biodiesel production and municipal wastewater treatment. However, there is scant information reporting systematic studies on screening and optimization of key supplemented components in the coupling system. The main factors were scientifically screened and optimized using statistical methods. Plackett–Burman design (PBD) was used to explore the roles of added nutrient factors, whereas response surface methodology (RSM) was employed for optimization. Based on the statistic analysis, the optimum added TP and FeCl 3 ·6H 2 O concentrations for Scenedesmus obliquus -like microalgae growth, nutrients uptake and lipid accumulation were 4.41 mg L −1 and 6.48 mg L −1 , respectively. The corresponding biomass, lipid content and TN/TP removal efficiency were 1.46 g L −1 , 36.26% and >99%. The predicted value agreed well with the experimental value, as determined by validation experiments, which confirmed the availability and accuracy of the model. [ABSTRACT FROM AUTHOR]

This study presents experimental measurements of the biochemical methane production for whole and lipid extracted Nannochloropsis salina . Results show whole microalgae produced 430 cm 3 -CH 4 g-volatile solids −1 (g-VS) ( σ = 60), 3 times more methane than was produced by the LEA, 140 cm 3 -CH 4 g-VS −1 ( σ = 30). Results illustrate current anaerobic modeling efforts in microalgae to biofuel assessments are not reflecting the impact of lipid removal. On a systems level, the overestimation of methane production is shown to positively skew the environmental impact of the microalgae to biofuels process. Discussion focuses on a comparison results to those of previous anaerobic digestion studies and quantifies the corresponding change in greenhouse gas emissions of the microalgae to biofuels process based on results from this study. [ABSTRACT FROM AUTHOR]

Industrial CO 2 -rich flue-gases, owing to their eco-toxicity, have yet to be practically exploited for microalgal biomass and lipid production. In this study, various autotrophic and mixotrophic culture modes for an oleaginous microalga, Chlorella sp. KR-1 were compared for the use in actual coal-fired flue-gas. Among the mixotrophic conditions tested, the fed-batch feedings of glucose and the supply of air in dark cycles showed the highest biomass (561 mg/L d) and fatty-acid methyl-ester (168 mg/L d) productivities. This growth condition also resulted in the maximal population of microalgae and the minimal population and types of KR-1-associated-bacterial species as confirmed by particle-volume-distribution and denaturing-gradient-gel-electrophoresis (DGGE) analyses. Furthermore, microalgal lipid produced was assessed, based on its fatty acid profile, to meet key biodiesel standards such as saponification, iodine, and cetane numbers. [ABSTRACT FROM AUTHOR]

The effects of ultrasonic treatment on fractal microstructures of wet microalgal cells were investigated for lipid extraction. Fractal dimension of cells with distorted surfaces increased with power and ultrasonication time. Microalgal cells shrank owing to dehydration and cytomembranes were reduced to debris, but cell walls were not fragmented. When ultrasonication power increased from 0 to 500 W for 30 min, the fractal dimension of cells increased from 1.21 to 1.51, cell sizes decreased from 2.78 to 1.68 μm and cell wall thickness decreased from 0.08 to 0.05 μm. When ultrasonication time increased from 5 to 30 min with a power of 150 W, the fractal dimension of cells increased from 1.24 to 1.37, cell sizes decreased from 2.72 to 2.38 μm and cell wall thickness first increased to a peak of 0.22 μm and then decreased. Long-chain and unsaturated lipids were degraded into short-chain and saturated lipids with ultrasonic cavitation. [ABSTRACT FROM AUTHOR]

Heterotrophic cultivation of Chlorella vulgaris was investigated in food waste hydrolysate. The highest exponential growth rate in terms of biomass of 0.8 day −1 was obtained in a hydrolysate consisting of 17.9 g L −1 glucose, 0.1 g L −1 free amino nitrogen, 0.3 g L −1 phosphate and 4.8 mg L −1 nitrate, while the growth rate was reduced in higher concentrated hydrolysates. C. vulgaris utilized the nutrients recovered from food waste for the formation of biomass and 0.9 g biomass was produced per gram glucose consumed. The microalgal biomass produced in nutrient sufficient batch cultures consisted of around 400 mg g −1 carbohydrates, 200 mg g −1 proteins and 200 mg g −1 lipids. The conversion of nutrients derived from food waste and the balanced biomass composition make C. vulgaris a promising strain for the recycling of food waste in food, feed and fuel productions. [ABSTRACT FROM AUTHOR]

Renewable fuels and energy are of major concern worldwide and new raw materials and processes for its generation are being investigated. Among these raw materials, algae are a promising source of lipids and energy. Thus, in this work four different algae have been used for lipid extraction and biogas generation. Lipids were obtained by supercritical CO 2 extraction (SCCO 2 ), while anaerobic digestion of the lipid-exhausted algae biomass was used for biogas production. The extracted oil composition was analyzed (saturated, monounsaturated and polyunsaturated fatty acids) and quantified. The highest lipid yields were obtained from Tetraselmis sp. (11%) and Scenedesmus almeriensis (10%), while the highest methane production from the lipid-exhausted algae biomass corresponded to Tetraselmis sp . (236 mL CH 4 /g VS added ). [ABSTRACT FROM AUTHOR]

Increasing energy demand and depleting fossil fuel sources have intensified the focus on biofuel production. Microalgae have emerged as a desirable source for biofuel production because of high biomass and lipid production from waste water source. In this study, five microalgae were isolated from effluents of Nisargruna biogas plants. These isolates were identified based on morphology and partial 18S and 23S rRNA gene sequences. Growth and lipid accumulation potential of these microalgae were investigated. One isolate, Chlorella sp. KMN3, accumulated high biomass (1.59 ± 0.05 g L −1 ) with moderate lipid content (20%), while another isolate Monoraphidium sp. KMN5 showed moderate biomass accumulation of 0.65 ± 0.05 g L −1 with a very high (35%) lipid content. The fatty acid methyl esters mainly composed of C-16:0, C-18:0, C-18:1 and C-18:2. This observation makes these microalgae immensely potential candidate for biodiesel production using the effluent of a biogas plant as feed stock. [ABSTRACT FROM AUTHOR]

Effects of Fe 3+ (0–0.12 g/L), Mg 2+ (0–0.73 g/L) and Ca 2+ (0–0.98 g/L) on the biomass and lipid accumulation of heterotrophic microalgae were investigated in dark environment. The biomass and lipid production exhibited an increasing trend with increasing the concentrations of metal ions. In cultures with 1.2 × 10 −3 g/L Fe 3+ , 7.3 × 10 −3 g/L Mg 2+ and 9.8 × 10 −4 g/L Ca 2+ , the maximum biomass, total lipid content and lipid productivity reached 3.49 g/L, 47.4% and 275.7 mg/L/d, respectively. More importantly, EDTA addition (1.0 × 10 −3 g/L) could enhance the solubility of metal ions (iron and calcium) and increase their availability by microalgae, which evidently promote the lipid accumulation. Compared with the control, the total lipid content and lipid productivity increased 28.2% and 29.7%, respectively. These show that appropriate concentrations of metal ions and EDTA in the culture medium were beneficial to lipid accumulation of heterotrophic Scenedesmus sp. cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • Water-plasma was first employed to disrupt microalgae cell walls. • Water-plasma was extremely effective at disrupting cell walls. • Combined water-plasma and TPP were able to recover 74.34% lipid within 10 min. • Proposed process prevented drying step of biomass and reduced energy consumption. Traditional methods for lipid extraction from microalgal biomass usually involve harsh reaction conditions or the use of contaminant reagents, which lead to enormous energy consumption and wastage. Hence, a novel strategy was presented, which combined water-plasma and three-phase partitioning (TPP) techniques. Benefiting from its unique advantages such as rapid and low cost, water-plasma strategy can disrupt microalgal cell wall and can thus greatly affect lipid extraction. As a result, assisted with the TPP method, excellent performance lipid recovery (74.34%) was obtained at 200 W in 10 min. The performance was superior to that achieved through cell disruption via water-plasma pretreatment. Importantly, the whole process of lipid extraction prevented the drying of microalgal biomass, contributing to reduced energy consumption in large-scale biodiesel production. Moreover, the high fatty acids content suggested that the extracted lipids are great potential candidate for biodiesel production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Distillery spentwash (SW) was used to produce lipids and VFAs by oleaginous yeasts. • Trichosporon cutaneum produced 29.8% and 0.89 g/L lipids with acid hydrolysed SW. • Dual-stage fermentation enhanced lipid productivity by 15% in Tc. • Effect of sulphates and ammonium on lipid biosynthesis was elucidated. • A biorefinery framework was elucidated to enable circular chemistry using yeast. Yeast lipids from low-cost renewable feedstock are valuable resources for oleochemicals thus enabling circular chemistry. Current study focuses on lipid and volatile fatty acid (VFA) production through dual-stage fermentation of spentwash in a biorefinery framework with Trichosporon cutaneum (Tc) and Yarrowia lipolytica (Yl). During cell proliferation phase, Tc and Yl accumulated 2.9 and 2.5 g/L of dry biomass respectively in acid-hydrolysed spentwash (AHSW) and produced 16 and 5.5 g/L of total VFA respectively. Lipid yields (29.8%) and lipid titres (0.89 g/L) were higher in Tc /AHSW, when compared to Yl indicating the efficacy of Tc in spentwash bioremediation. Lipid accumulation was enhanced to 35% in Tc /AHSW, in presence of 0.05% NH 4 Cl due to oxidative stress of ammonium ions. Analysis of fatty acid composition revealed the presence of higher oleic acid, which is ideal for biodiesel production. The results demonstrate a sustainable biorefinery model for bioremediation of spentwash and its value addition. [ABSTRACT FROM AUTHOR]

• Lipid content was improved by GABA coupled with Cu2+ stress. • GABA regulated reactive oxidative species (ROS) signalling under Cu2+ stress. • GABA coupled with Cu2+ stress upregulated the levels of lipid-related genes and atg8. • Autophagy activation influenced lipid synthesis in alga under GABA and Cu2+ stress. Induction of copper ion (Cu2+) stress is a method used to increase lipid accumulation in microalgae, but it decreases cell growth. In this work, the impacts of gamma-aminobutyric acid (GABA) coupled with Cu2+ stress on the biomass and oil yield in Monoraphidium sp. QLY-1 were investigated. Results suggested that the combined treatment of GABA and Cu2+ resulted in a higher lipid content (55.13%) than Cu2+ treatment (48.43%). Furthermore, GABA addition upregulated the levels of lipid-relevant genes, cellular GABA, ethylene (ETH), and antioxidant enzyme activities and alleviated oxidative damage caused by Cu2+ stress. The autophagy-relevant gene atg8 was also upregulated by GABA treatment. Further exploration indicated that cell autophagy induced the lipid content up to 58.09% with GABA and Cu2+ stress treatment. This investigation demonstrates that the coupling strategy can stimulate lipid production and shed light on the underlying mechanisms in lipid biosynthesis, cell autophagy, and stress response of microalgae. [ABSTRACT FROM AUTHOR]

[Display omitted] • Intrinsic interactions between lipid feedstocks and lipid-based biofuels. • Advancements in lipid-associated biofuel technology. • Properties and applicability of various lipid sources for biofuel production. • Biotechnology and progress in lipid production for advanced biofuels. The expanding use of fossil fuels has caused concern in terms of both energy security and environmental issues. Therefore, attempts have been made worldwide to promote the development of renewable energy sources, among which biofuel is especially attractive. Compared to other biofuels, lipid-derived biofuels have a higher energy density and better compatibility with existing infrastructure, and their performance can be readily improved by adjusting the chemical composition of lipid feedstocks. This review thus addresses the intrinsic interactions between lipid feedstocks and lipid-based biofuels, including biodiesel, and renewable equivalents to conventional gasoline, diesel, and jet fuel. Advancements in lipid-associated biofuel technology, as well as the properties and applicability of various lipid sources in terms of biofuel production, are also discussed. Furthermore, current progress in lipid production and profile optimization in the context of plant lipids, microbial lipids, and animal fats are presented to provide a wider context of lipid-based biofuel technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • The opportunity of heterologous carbonic anhydrase in CC-400 was evaluated. • This is the first attempt to cultivate CC-400 strain under autotrophic condition. • The carbon capture was achieved to 2.75 g-CO 2 /g-DCW in the optimal condition. • The biomass, lutein, and lipid were increased 2-, 4- and 8-folds in modified CC-400. • Transcriptional levels of major genes in the pathway decipher CA effect in CC-400. Chlamydomonas reinhardtii is a model microalga that has a higher growth rate and produces high levels of lutein and lipids, but biomass production is limited. Carbonic anhydrase (CA) converts atmospheric CO 2 to bicarbonate which is crucial for carbon‐concentrating mechanism (CCM) in microalgae and boosts cell density. Therefore, C. reinhardtii harboring the heterologous CA from Mesorhizobium loti (MlCA) and Sulfurihydrogenibium yellowstonense (SyCA) were explored to increase CO 2 capture and utilization (CCU) through different culture devices. Genetically modified C. reinhardtii was able to grow from mixotrophic to autotrophic conditions. Subsequently, biomass, lutein, and lipid were maximized to OD 680 of 4.56, 21.32 mg/L and 672 mg/L using photo-bioreactor (PBR) with 5% CO 2. Moreover, CO 2 assimilation rate was 2.748 g-CO 2 /g-DCW and 2.792 g-CO 2 /g-DCW under mixotrophic and autotrophic conditions, respectively. The biomass accumulation correlated with CA activity. In addition, the transcript levels of major genes in metabolic pathways of lutein and lipid were dramatically increased. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biomass production of microalgae in river water as a medium. • Microalgae removed a high rate of organic and inorganic pollutants. • FAME derived from biomass showed suitable applications as feed and green fuel. • River water phycoremediation is essential for a healthy environment. The present study evaluated polluted river water as a medium for the growth of oleaginous microalgae under mixotrophic conditions. Microalgae grow in the medium and produce biomass, pigments, and lipids with the removal of pollution loads from wastewater. Selenastrum sp. SL7 produced maximum biomass and lipids of 660 mg L-1 and 194.5 mg L-1, respectively. Fatty acid profiling data showed that elevated saturated fatty acid production and major fatty acids found in lipid from these algae were palmitic acids, oleic acid, stearic acid, linolenic acid, and linoleic acid. The low percentage of polyunsaturated fatty acids of EPA was also detected. Water quality in terms of pH, DO, TDS, COD, and BOD was significantly improved. The use of this medium for microalgae cultivation not only improves the biomass and lipid yields but also serves as an excellent means of phycoremediation of pollutants in waste streams with value addition and environmental benefits. [ABSTRACT FROM AUTHOR]

[Display omitted] • A potential lutein-producing isolate identified as Chlorella sorokiniana Kh12. • A 2X-HT-9 k condition offered the maximum lutein yield (47.36 mg l−1) under mixotrophy. • It has yielded maximum lutein 13.69 mg g−1, one of the best yields reported so far. • Bead milling was most effective to disrupt algal cell wall and lutein extraction. • Seven minutes bead milling was most efficient for maximum lutein extraction. A bioprospecting study was conducted from Seawater samples collected at Kaohsiung Seacoast, Taiwan. The current research was aimed to isolate potential lutein-producing strain, evaluate and optimize the best cultivation mode, lutein accumulation stage, lutein-extraction method, and condition to recover maximum lutein (main product) and lipid (byproduct). Biorefinery is the latest approach worldwide to extract multi-products for cost-effectiveness. Selected isolate among several isolates, identified as Chlorella sorokiniana Kh12 and exploited under biorefinery concept for lutein and lipid extraction. Kh12 cultivated under mixotrophy: 2X-(HT)-9k yielded maximum biomass (3.46 g L−1) and lutein (13.69 mg g−1) which is among the higher yields reported so far. Among various tested solvents, methanol was the best extractor. Bead milling was most effective to disrupt algal cell walls, seven minutes of milling was best for maximum lutein (7.56 mg g−1) extraction. Kh12 could be a promising candidate for commercial lutein and lipid co-production based on the outcome. [ABSTRACT FROM AUTHOR]

The potential of nitrogen sources supplementing domestic wastewater for the cultivation of microalgae was assessed. Urea, potassium nitrate, sodium nitrate and ammonium nitrate were evaluated for their effect on cultivation and lipid production of Chlorella sorokiniana . Urea showed the highest biomass yield of 0.220 g L -1 and was selected for further experimentation. Urea concentrations (0-10 g L -1 ) were assessed for their effect on growth and microalgal physiology using pulse amplitude modulated fluorometry. A concentration of 1.5 g L -1 urea produced 0.218 g L -1 biomass and 61.52% lipid by relative fluorescence. Physiological stress was evident by the decrease in relative Electron Transport Rate from 10.45 to 6.77 and quantum efficiency of photosystem II charge separation from 0.665 to 0.131. Gas chromatography analysis revealed that C16:0, C18:0, C18:1, C18:2 and C18:3 were the major fatty acids produced by C. sorokiniana . Urea proved to be an effective nitrogen supplement for cultivation of C. sorokiniana in wastewater. [ABSTRACT FROM AUTHOR]

Nannochloropsis have attracted sustained interest from algal biodiesel researchers due to their high biomass accumulation rate and high lipid content. There are six recognized species in the Nannochloropsis genus that are phylogenetically divided into Nannochloropsis gaditana, Nannochloropsis salina, Nannochloropsis granulata, Nannochloropsis limnetica, Nannochloropsis oceanica and Nannochloropsis oculata. In this study, the potential of 9 Nannochloropsis species from the 6 genus for biodiesel production was evaluated by determining their growth rate, biomass accumulation, lipid productivity, lipid composition, fatty acid profiles and biodiesel properties. The results showed that the best strain was N. oceanica IMET1, with lipid productivity of 158.76 ± 13.83 mg L-1 day-1, TAG production of 1.67 ± 0.20 g/L, favorable fatty acid profiles of C16-C18 (56.62 ± 1.96%) as well as suitable biodiesel properties of higher cetane number (54.61 ± 0.25), lower iodine number (104.85 ± 2.80 gI2/100 g) and relative low cloud point (3.45 ± 0.50 °C). N. oceanica IMET1 could be consider as valuable feedstock for microalgal biodiesel production. [ABSTRACT FROM AUTHOR]

Improvement on electron shuttle-mediated extracellular electron transfer (EET) is of great potential to enhance the power output of MFCs. In this study, sophorolipid was added to enhance the performance of Pseudomonas aeruginosa-inoculated MFC by improving the electron shuttle-mediated EET. Upon sophorolipid addition, the current density and power density increased ∼1.7 times and ∼2.6 times, respectively. In accordance, significant enhancement on pyocyanin production (the electron shuttle) and membrane permeability were observed. Furthermore, the conditions for sophorolipid addition were optimized to achieve maximum pyocyanin production (14.47 ± 0.23 μ/mL), and 4 times higher power output was obtained compared to the control. The results substantiated that enhanced membrane permeability and pyocyanin production by sophorolipid, which promoted the electron shuttle-mediated EET, underlies the improvement of the energy output in the P. aeruginosa-inoculated MFC. It suggested that addition of biosurfactant could be a promising way to enhance the energy generation in MFCs. [ABSTRACT FROM AUTHOR]

Lipid and protein rich solid slaughterhouse wastes are attractive co-substrates to increase volumetric biogas production in co-digestion with dairy manure. Addition of decanter sludge (DS), containing 42.2% of lipids and 35.8% of proteins (total solids basis), up to 5% of feed mixture resulted in a stable process without any indication of long chain fatty acids (LCFA) or free ammonia (NH3) inhibition and in 3.5-fold increase of volumetric biogas production. Contrary, only lipids addition as technical fat (TF) at over 2% of feed mixture resulted in formation of floating granules (FG) and process efficiency decrease. Formed FG had low biodegradability and its organic part was composed of lipids and calcium salts of LCFAs. Anaerobic digestion process intentionally directed to FG formation, could be a viable option for mitigation and control of lipids overload and derived LCFA inhibition. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mixotrophic mode of cultivation induces higher biomass and lipid productivities. [•] Maintenance of light:dark cycle is crucial for efficient glucose uptake. [•] Low carbon is needed for growth whereas high carbon for lipid synthesis. [•] High nutrient removal was achieved and process can be easily scaled-up. [•] Increasing glucose concentrations affects FAME composition of lipids. [ABSTRACT FROM AUTHOR]

Highlights: [•] Target temperature and algae concentration have effect on cell wall disruption. [•] Best lipid yields are obtained at high temperatures and low biomass concentrations. [•] Low temperatures and low or high algae concentrations are suited for glucose yield. [•] The FAMEs found in larger amount after thermal extraction had 16–18 carbons. [Copyright &y& Elsevier]

Highlights: [•] Biomass and lipid yields achieved a theoretical model of 1+1>2 by mixed culture. [•] A double system bubble column photo-bioreactor was designed for mixing cultivation. [•] Growth curves of yeast and alga were confirmed in mixing cultivation system. [•] Real-time online detection of off-gas showed synergistic effects on O2/CO2 balance. [•] Analysis of metabolite variations proved synergistic effects on substance exchange. [Copyright &y& Elsevier]

Highlights: [•] Nutrient from algal hydrolysate showed excellent growth profile in Ettlia sp. [•] Organic carbon from SFW significantly increased lipid content. [•] Cells cultivated under AH and SFW showed improvement in FAME profile. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel combined hydrolysis was developed for fungal lipid fermentation. [•] Detoxification and pH adjustment were minimized for lignocellulosic biofuel production. [•] Lipid accumulation on hydrolysate had a comparable performance with the control. [ABSTRACT FROM AUTHOR]

Highlights: [•] Acid-catalyzed hot-water treatment for lipid extraction from wet microalgae. [•] The optimal lipid-extraction condition of 1.00% sulfuric acid concentration. [•] Extraction of docosahexaenoic acid (DHA)-rich lipids from Aurantiochytrium sp. [Copyright &y& Elsevier]

Highlights: [•] R. toruloides 2F5 produced high amount of oil from inulin and larger lipid bodies. [•] 70.4% (w/w) of lipid based on cell dry weight was produced from 6.0% (w/v) inulin. [•] Over 99.09% of the fatty acids was C16:0, C18:0, C18:1 and C18:2. [•] The biodiesel prepared from the lipid could be burned well. [Copyright &y& Elsevier]

Highlights: [•] Strain PD630 can tolerate low concentration of five model inhibitory compounds. [•] Strain PD630 can use vanillic acid and TPCA for cell growth and TAG accumulation. [•] Vanillin can be used as a carbon source, but TAGs are not accumulated. [•] Strain PD630 can grow on three lignocellulosic hydrolysates and accumulate TAGs. [Copyright &y& Elsevier]

Highlights: [•] Marine diatom Chaetoceros muelleri grow well under high CO2 levels (10–20%). [•] The highest biomass, total and neutral lipid contents were all found under 10% CO2. [•] Total lipid content is 43.40% DW under 10% CO2 with highest biomass productivity. [•] Fatty acid composition of C. muelleri is very ideal for biofuels production. [•] C. muelleri have great potential to biodiesel produce using the flue gases. [Copyright &y& Elsevier]

Highlights: [•] Structural correlation between cellular development and lipid body accumulation. [•] HTP screening of thraustochytrid using FACS with different fluorescent dyes. [•] Found that BODIPY 505/515 with less concentration of DMSO effective for FACS. [•] Established a quantitative baseline for lipids accumulation and/or microalgal growth. [Copyright &y& Elsevier]

Highlights: [•] Chlorella pyrenoidosa XQ-20044 is able to accumulate lipids in growing cells. [•] One step production of algal lipid was achieved in chemostat culture. [•] Proper SNI was the key for simultaneous algal growth and lipid accumulation. [•] Lipid productivity was significantly enhanced by continuous culture. [Copyright &y& Elsevier]

Highlights: [•] SMP for whole microalgae were better than lipid-extracted microalgae residues. [•] The control of I/S ratio during BMP could overcome pH drop and LCFA inhibition. [•] No signs of VFA or ammonia inhibition occurred when digested at I/S⩾1.0 ratio. [•] Higher methane production was not related to species but to lipid content of biomass. [Copyright &y& Elsevier]

Highlights: [•] A dual strategy for wastewater treatment and biofuel feedstock production. [•] Mine wastewater increased the nutrient removal efficiency of M. reisseri. [•] Mine wastewater improved the growth and lipid productivity of M. reisseri. [•] Concentrated municipal wastewater supported the algal autoflocculation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Lipomyces starkeyi exhibited the highest productivities using undetoxified H-H. [•] The simultaneous utilization of glucose and xylose for lipid production was observed. [•] High cell mass and lipid concentrations were obtained at repeated fed-batch strategy. [•] Highest cell mass and lipid yields were obtained at a low dilution rate of 0.03h−1. [•] The fatty acid composition profile was notably similar to that of palm oil. [ABSTRACT FROM AUTHOR]

Highlights: [•] Investigated the effects of temperature and irradiation on biomass and production. [•] The optimum C/N ratio for lipid and carotenoid synthesis was ∼90. [•] Concentrated broth enhanced products yields and reduced the residual sugar. [•] A new two-stage cultivation method significantly improved the yields of products. [ABSTRACT FROM AUTHOR]