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[Display omitted] • Microalga and free feeds degraded in percentages of 1.5 and 24% respectively. • No antioxidant treatment is necessary for feed storage during 1.5 year period. • First time evaluated the price of microalgae feeds in a viable manner. The rising prices of fishery derivatives limits their use in aquafeeds. Therefore, other alternatives are used to replace those ingredients. Among them, microalgae are of great interest both as an ingredient and as a potential stabilising agent against lipid oxidation. This study evaluates on the use of Nannochloropsis gaditana to prevent lipid oxidation in a set of 12 aquafeeds over 540 days of storage. Aquafeeds were formulated with/without 15 % N. gaditana combined with two antioxidants −butylhydroxytoluene (25–150 mg·kg-1) or vitamin E (500–3000 mg·kg-1). The effect of i) storage period, ii) presence of microalgae and iii) antioxidant addition on lipid oxidation was assessed. Results showed higher fatty acid degradation in diets lacking microalgae. The microalgae supplemented diets is enough for preserving feeds presenting the highest antioxidant effect at the end, without significant differences with the microalgae-supplemented feeds and those including antioxidants after 540 days of storage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimization of microalgae culture through a two-stage cultivation strategy. • Biomass accumulation was enhanced by 23.62% under optimal conditions. • Optimal dual stress enhanced lipid and SFA content by 128.38% and 56.30%. • Microalgae recycling efficiency increased under dual stress environments. In this study, a two-stage culture strategy was refined to concurrently enhance the growth and lipid accumulation of Tetradesmus obliquus. The results unveiled that, during the initial stage, the optimal conditions for biomass accumulation were achieved with 0.02 mg·L−1 Cu2+ concentration and red light. Under these conditions, biomass accumulation reached 0.628 g·L−1, marking a substantial 23.62 % increase compared to the control group. In the second stage, the optimal conditions for lipid accumulation were identified as 0.5 mg·L−1 Cu2+ concentration and red light, achieving 64.25 mg·g−1·d−1 and marking a 128.38 % increase over the control. Furthermore, the fatty acid analysis results revealed an 18.85 % increase in the saturated fatty acid content, indicating enhanced combustion performance of microalgae cultivated under the dual stress of red light and 0.5 mg·L−1 Cu2+. This study offers insights into the potential application of Tetradesmus obliquus in biofuel production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Multifactor regulation improved the biomass and lipids in Chlamydomonas reinhardtii. • The optimal cultivation conditions were 30 °C, 150 μE/m2/s, and 24/0h photoperiod. • The maximal biomass and lipid content in C. reinhardtii reached 1.92 g/L and 41.10 %. • Lipid productivity was promoted by 3.01 times under optimized culture conditions. • The biodiesel properties were enhanced by altering temperature and light regimes. This study investigated the impacts of various culture temperatures and light regimes on growth and biochemical constituents of Chlamydomonas reinhardtii under carbon-supply and nitrogen-limited conditions to improve oil production in algal cells. Results displayed that under a 30 ℃ and 150 μE/m2/s regime, there was a significant increase in biomass, total lipids, and lipid productivity. Specifically, these parameters reached 1.83 g/L, 36.25 %, and 130.73 mg/L/d, respectively. Remarkably, prolonging the photoperiod further enhanced the aforementioned three parameters, reaching peak levels of 1.92 g/L, 41.10 %, and 157.54 mg/L/d, respectively, recorded at a 24/0h photoperiod. Compared with cultures grown under normal conditions, these values displayed increments of 1.21-fold, 74.88 %, and 3.01-fold, respectively. Additionally, under optimal conditions, the soluble sugar content reached 79.72 mg/g, and the biodiesel properties were improved. These findings indicate that moderately increasing temperature, light intensity, and photoperiod could achieve the co-production of biomass, lipids, and sugars in C. reinhardtii. [ABSTRACT FROM AUTHOR]

[Display omitted] • C. sorokiniana showed superior tolerance capacity on high acetate dosage up to 30 g/L. • Heterotrophy benefits to algal growth and lipogenesis when supplying 20 g/L acetate. • Inhibition of photosynthesis led to poor mixotrophic growth under 20 g/L acetate. • Heterotrophy produced superior amino acid profiling and more linoleic acid (50%). • Heterotrophic repeat fed-batch mode resulted in 23.4 g/L biomass and 7.0 g/L lipid. The low-cost carbon source, acetate, was utilized to feed a linoleic acid-rich Chlorella sorokiniana for microalgal biomass and lipid accumulation. Remarkably high tolerance capability to high acetate dosage up to 30 g/L was observed, with heterotrophy being the preferred trophic mode for algal growth and lipogenesis when supplemented 20 g/L acetate. Transcriptome analysis revealed a marked activation of pathways involved in acetate bioconversion and lipogenesis upon exposure to high-level of acetate. However, the enhancement of photorespiration inhibited photosynthesis, which ultimately led to a decrease in biomass and lipid under mixotrophy. Heterotrophic acetate-feeding generated more superior amino acid profiling of algal biomass and a predominant linoleic acid content (50 %). Heterotrophic repeat fed-batch strategy in 5 L fermenter significantly increased the growth performance and lipid titer, with the highest levels achieved being 23.4 g/L and 7.0 g/L, respectively. This work provides a viable approach for bio-products production through acetate-based heterotrophic algal cultivation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fed-batch fermentation achieved the highest lipid and biomass reported in Mucor. • The biochemical profile of fed-batch fermentation obtained products was examined. • The expression levels of key genes involved in lipid synthesis had up-regulated. • Numerous abiotic factors thrived during the optimization of fed-batch cultivation. This study aimed to improve the lipid and biomass yields of Mucor circinelloides WJ11 by implementing four different fed-batch fermentation strategies, varied in time and glucose concentration (S1-S4). The S1 fermentation strategy yielded the highest biomass, lipid, and fatty acid content (22 ± 0.7 g/L, 53 ± 1.2 %, and 28 ± 1.6 %) after 120 and 144 h, respectively. The γ-linolenic acid titer of 0.75 ± 0.0 g/L was greatest in S3 after 48 h. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to analyze the transcription of key genes involved in lipid accumulation. The glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and ATP-citrate lyase genes showed increased expression levels. Fourier-transform infrared (FTIR) spectroscopy was used to analyze the biochemical profile during fermentation strategies. Optimal abiotic factors for production efficiency included pH 6.5, 25–26 °C, 15 % (v/v) inoculum, 500 rpm, 20 %-30 % dissolved oxygen, and 120 h fermentation. Glucose co-feeding offers valuable insights to develop effective fermentation strategies for lipid production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oleaginous yeast grown on solid lipid-rich side stream Cocoa Fatty Acid Distillate. • Adaptive Laboratory Evolution (ALE) enhanced growth and single cell oil production. • ALE improved biomass by >2-fold and lipid content by 3- to 4-fold. • Transcriptomics reveal potential mechanism which improve growth and lipid content. • Oleaginous yeast strains generated with high amounts of saturated lipid content. Single cell oil production using oleaginous yeasts is a promising alternative to animal and plant-derived lipids. But substrate costs for microbial fermentation are a major bottleneck. Using side streams as alternative to substrates like glucose, for growing yeast, is a potential cost-effective solution. By combining a previously reported process of growing yeasts on a solid cocoa fatty acid distillate side stream with adaptive evolution techniques, the growth of oleaginous yeast Yarrowia lipolytica was improved by 2-fold. The lipid titre was also boosted by more than 3-fold. Using transcriptomics, key genes were identified that are possibly involved in tailoring of lipid composition, side stream utilisation and enhancement of lipid titres. Candidate genes were also identified that might enable efficient growth and utilization of fatty acids and triacylglycerides found in cocoa fatty acid distillate. In summary, this research has improved the understanding of side stream utilisation for lipid production in oleaginous yeast. [ABSTRACT FROM AUTHOR]

[Display omitted] • ARTP-ethanol co-mutation for synchronous enhancement of lipid and astaxanthin. • Improved key enzyme activity, gene expression for lipid and astaxanthin biosynthesis. • Elucidated mechanisms of lipid and astaxanthin accumulation by ARTP and ethanol. • Upregulation of genes nubpl , Abcc 2, PAO related to lipid and astaxanthin accumulation. Haematococcus lacustris is a precious algal species renowned for its ability to simultaneous production of astaxanthin and lipid. However, its slow growth rate necessitates the development of appropriate mutagenesis methodologies to effectively enhance its synchronous production of both astaxanthin and lipid. This study introduced the co-mutation of Atmospheric and Room Temperature Plasma (ARTP) and ethanol. The performance and preliminary mechanisms underlying the combined accumulation of astaxanthin and lipid in H. lacustris under both mutations by ARTP and ethanol were comparatively analyzed. Combined astaxanthin and lipid contents relative to total cell mass in the 110–2 strain reached 54.4%, surpassing that of strain 0–3 and the control by 17.0% and 47.6% respectively. Transcriptome level analysis revealed how both ethanol and ARTP induction promote the expressions of carotenoid and lipid synthesis genes and related enzymatic activities. Upregulation of genes associated with cell activity contributed to lipid and astaxanthin metabolism in multi pathways. [ABSTRACT FROM AUTHOR]

• Nutrient enrichment enhanced the biomass and lipid productivity in C. gracilis. • Protein, carbohydrate and lipid content was highest in 2 f setup of T. weissflogii. • Nutrient limitation enhanced phenol and flavonoid content in T. weissflogii. Marine diatoms have high adaptability and are known to accumulate lipids under nutrient stress conditions. The present study involves determining the effect of varying macro and micronutrients on growth kinetics and metabolite production of oleaginous marine diatoms, Thalassiosira weissflogii and Chaetoceros gracilis. The results highlighted that C. gracilis and T. weissflogii showed maximum biomass yield of 0.86 ± 0.06 g/L and 0.76 ± 0.01 g/L in the 2 f and f supplemented medium respectively. A 2.5-fold increase in cellular lipid content was recorded in the 2 f culture setup of both strains ranging from 20 % to 26.7 % (w/w). The study also reveals that high eutrophic nutrient media (f , 2 f and 4 f) triggered biomass productivity as well as total protein and carbohydrate content in both strains. Thus, providing a reproducible insight of trophic flexibility of diatoms, concomitant with the increment in multiple commercially valuable products. [ABSTRACT FROM AUTHOR]

Mechanism of enhanced microalgal biomass and lipid accumulation through symbiosis between a highly succinic acid-producing strain of Escherichia coli SUC and Aurantiochytrium sp. SW1. [Display omitted] • E. coli SUC was screened to establish a symbiotic system with SW1. • E. coli SUC promoted the growth of SW1 by dual regulation mechanism. • Under optimized conditions, SW1 achieved biomass of 27.83 g/L and lipids of 4.87 g/L. Microalgae, known for rapid growth and lipid richness, hold potential in biofuels and high-value biomolecules. The symbiotic link with bacteria is crucial in large-scale open cultures. This study explores algal-bacterial interactions using a symbiotic model, evaluating acid-resistant Lactic acid bacteria (LAB), stress-resilient Bacillus subtilis and Bacillus licheniformis , and various Escherichia coli strains in the Aurantiochytrium sp. SW1 system. It was observed that E. coli SUC significantly enhanced the growth and lipid production of Aurantiochytrium sp. SW1 by increasing enzyme activity (NAD-IDH, NAD-ME, G6PDH) while maintaining sustained succinic acid release. Optimal co-culture conditions included temperature 28 °C, a 1:10 algae-to-bacteria ratio, and pH 8. Under these conditions, Aurantiochytrium sp. SW1 biomass increased 3.17-fold to 27.83 g/L, and total lipid content increased 2.63-fold to 4.87 g/L. These findings have implications for more efficient microalgal lipid production and large-scale cultivation. [ABSTRACT FROM AUTHOR]

[Display omitted] • S stress induced rapid accumulation of lipids in T. minus up to 54% of DW. • High concentration of SO 4 2− markedly increased the N uptake and biomass of T. minus. • Two-step culture is an effective method to promote lipid and POA production. • The lipid content of T. minus was negatively correlated with the cellular S content. Tribonema minus , a promising filamentous oleaginous microalga, was cultured under different nutrient concentrations and different culture modes (fed-batch culture, two-step culture) to study the method of rapid regulation of its lipid metabolism. In contrast to many other oleaginous microalgae, T. minus did not show that nitrogen stress promoted lipid accumulation; however, sulfur deficiency promoted rapid lipid accumulation with a maximum lipid content of 54% of dry weight. Increasing the MgSO 4 concentration significantly increased nitrogen uptake and biomass (10.09 g/L). Lipid productivity was significantly increased by the two-step culture using a medium with a high concentration of MgSO 4 in the first step and a sulfur-free medium in the second step. In addition, it was found that the lipid content of T. minus was negatively correlated with the intracellular sulfur content when the intracellular sulfur content was below 0.6%. This study provides a new approach for industrial lipid production in T. minus. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel self-flocculating blue-green microalga Limnothrix sp. was isolated. • High self-flocculating efficiency (>90 %) was obtained in municipal wastewater. • It showed both excellent growth and lipid production performance. • Self-flocculation is related to extracellular proteins, calcium and magnesium ions. • Blue light induced algal aggregation due to extracellular polysaccharides secretion. The present study evaluated the growth, self-flocculation, lipid content, and pollutants removal by Limnothrix sp. BASMWW-9 isolated from municipal wastewater treatment system and cultivated in municipal wastewater. The biomass yield and lipid content after 6 days of cultivation were 1.07 g dw/L and 27.34 %dw, respectively. In addition, its self-flocculating ability reached up to 90 % after harvesting time of 180 min. Moreover, COD, NH 3 -N, TN, and TP removal efficiencies were 71.65 %, 81.89 %, 74.64 %, and 80.16 %, respectively. The self-flocculation performance of Limnothrix sp. was greatly associated to its morphology and production of extracellular polymeric substances (EPS), with significant positive impact of the high calcium and magnesium content in municipal wastewater. Interestingly, blue light irradiation during harvest enhanced the aggregation and floc formation as a floating biomat, which was attributed to enhanced polysaccharides production. This study provides innovative harvest method for Limnothrix sp. BASMWW-9 cultivated in wastewater using blue light for enhanced lipid recovery. [ABSTRACT FROM AUTHOR]

• Deep-learning-based image recognition was developed for lipid quantification of yeast culture. • The trained model detected cell and lipid droplets with high accuracy. • The trained model monitored lipid droplets in real-time using simple light microscopic images. • The image-based lipid quantification showed high accuracy comparable to GC–MS. Intracellular lipid droplets (LDs), subcellular organelles playing a role in long-term carbon storage, have immense potential in biofuel and dietary lipid production. Monitoring the state of LDs in living cells is of utmost importance for quick biomass harvest and screening promising isolates. Here, a deep-learning-based segmentation model was developed for automatic detection and segmentation of LDs using the model yeast species Lipomyces starkeyi , leading to fast and accurate quantification of lipid contents in liquid cultures. The trained model detected the yeast's cell and LDs in light microscopic images with an accuracy of 98% and 92%, respectively. Lipid content prediction using pixel numbers counted in segmented LDs showed high similarity to lipid quantification results obtained with gas chromatography-mass spectrometry. This automated quantification can highly reduce cost and time in real-time monitoring of lipid production, thereby providing an efficient tool in bio-fermentation. [ABSTRACT FROM AUTHOR]

• Seven common herbal extraction residues (HERs) were compared for lipid production. • Radix paeoniae alba residue (RPAR) was superior for sugar and lipid production. • Reuse of pretreatment liquor (PL) for RPAR pretreatment obtained 241.6 g/L sugars. • Fed-batch culture of the PL as feeding medium led to high lipid production. • Micro-biodiesel prepared from the HERs showed high-quality fuel properties. Valorization of herbal extraction residues (HERs) into value-added products is pivotal for the sustainability of Chinese medicine industry. Here, seven different enzymatic hydrolysates of dilute acid pretreated HERs were evaluated for lipid production by Cutaneotrichosporon oleaginosum. Among them, the highest sugar yield via hydrolysis and the maximum lipid production were obtained from Radix paeoniae alba residue (RPAR). More interestingly, high proportion of sugar polymers was disintegrated into fermentable sugars during the pretreatment step, allowing a cheap non-enzymatic route for producing sugars from RPAR. A repeated dilute acid pretreatment gained a high sugar concentration of 241.6 g/L through reusing the pretreatment liquor (PL) for four times. Biomass, lipid concentration, and lipid content achieved 49.5 g/L, 35.7 g/L and 72.2 %, respectively, using fed-batch culture of PL. The biodiesel parameters indicated lipids produced from HERs were suitable for biodiesel production. This study offers a cost-effective way to upgrade the HERs waste into micro-biodiesel. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two-stage fermentation process proposed for efficient bioconversion. • Engineered Y. lipolytica could convert syngas into β-carotene and lipids. • Tolerance up to 20 g/L acetic acid seen in the yeast strain. • Optimal lipid and β-carotene production were found at pH 6.0 in bioreactors. • The dominant lipid identified was C18:1, which is suited for biodiesel production. An engineered Yarrowia lipolytica strain was successfully employed to produce β-carotene and lipids from acetic acid, a product of syngas fermentation by Clostridium aceticum. The strain showed acetic acid tolerance up to concentrations of 20 g/L. Flask experiments yielded a peak lipid content of 33.7 % and β-carotene concentration of 13.6 mg/g under specific nutrient conditions. The study also investigated pH effects on production in bioreactors, revealing optimal lipid and β-carotene contents at pH 6.0, reaching 22.9 % and 44 mg/g, respectively. Lipid profiles were consistent across experiments, with C18:1 being the dominant compound at approximately 50 %. This research underscores a green revolution in bioprocessing, showing how biocatalysts can convert syngas, a potentially polluting byproduct, into valuable β-carotene and lipids with a Y. lipolytica strain. [ABSTRACT FROM AUTHOR]

[Display omitted] • C.curvatus concurrently assimilated GlcNAc and glucose for lipid production. • GlcNAc has the capacity to supply both carbon and nitrogen sources. • The co-fermentation of rice hydrolysates and chitin hydrolysate was effective. • Scaling-up experiments in a 5-L bioreactor resulted in lipid content of 60.1 %. • The fatty acid compositions of lipids were similar to that for vegetable oils. Microbial lipids were produced through a two-stage process with Cryptococcus curvatus by co-fermenting rice and shrimp shells hydrolysates. In the first stage, biomass production of glucose and N -acetylglucosamine was optimized by response surface methodology with the maximum biomass yield (17.60 g/L) under optimum conditions (43.2 g/L mixed sugar concentration, pH 5.8, 200 rpm, and 28 °C). In the second stage, according to a single-factor optimization setting (43.2 g/L sugar mixture solutions, pH 5.5, and shift time of 36 h), lipid titer of 10.08 g/L with content of 55.30 % was achieved. Scaling up to a 5-L bioreactor increased lipid content to 60.07 % with 0.233 g/g yield. When Cryptococcus curvatus was cultured in the blends of rice hydrolysates and shrimp shells hydrolysate, lipid content and yield were 52.25 % and 0.204 g/g. The fatty acid compositions of lipid were similar to those of typical vegetable oils. [ABSTRACT FROM AUTHOR]

[Display omitted] • Citricoccus sp. P2 degraded 44.63% of lignin and produced 23.96% of lipid content. • Citricoccus sp. P2 has demonstrated high effectiveness in LDCs conversion. • Genome sequencing revealed a biological funneling pathway for LDCs into lipid. • Lipid yield was 0.39 g/g LMS-treated lignin. • Non-sterilized fermentation efficiently improved lipid production from LDCs. Lignin-derived compounds (LDCs) bioconversion into lipids is a promising yet challenging task. This study focuses on the isolation of the ligninolytic bacterium Citricoccus sp. P2 and investigates its mechanism for producing lipids from LDCs. Although strain P2 exhibits a relatively low lignin degradation rate of 44.63%, it efficiently degrades various concentrations of LDCs. The highest degradation rate is observed when incubated with 0.6 g/L vanillic acid, 0.6 g/L syringic acid, 0.8 g/L p-coumaric acid, and 0.4 g/L phenol, resulting in respective lipid yields of 0.16 g/L, 0.13 g/L, 0.24 g/L, and 0.13 g/L. The genome of strain P2 provides insights into LDCs bioconversion into lipids and stress tolerance. Moreover, Citricoccus sp. P2 has been successfully developed a non-sterilized lipid production using its native alkali-halophilic characteristics, which significantly enhances the lipid yield. This study presents a promising platform for lipids production from LDCs and has potential to promote valorization of lignin. [ABSTRACT FROM AUTHOR]

[Display omitted] • 20 K-lux light/3x-nutrients exhibited max. astaxanthin 54.4 mg/L by C. zofingiensis. • 4–8 K-lux successive light increase and 5% CO 2 exhibited the best biomass yield. • The maximum lipid 37% accumulation was obtained at 5% CO 2 and 20 k-lux light. • 20 K-lux light/3x-nutrients exhibited max. astaxanthin content 16.7 mg/g DCW. • Two-stage designed bioprocess boosts astaxanthin yield of C. zofingiensis. Microalgal astaxanthin possesses numerous bioactivities and has several health applications. The current research focuses on designing and optimizing the two-stage mixotrophic bioprocess by Chlorella zofingiensis for astaxanthin production. Gradual increase in light intensity (4-8k-lux) and 3x micronutrient concentration were the key parameters for maximizing biomass yield of 2.5 g/L during 15 days of stage I. Furthermore, stress conditions (excessive CO 2, light, salinity, etc.) enhanced astaxanthin yield at stage II. 20k lux light, 3x nutrients, and 5% CO 2 were the best ranges for maximum astaxanthin production. Maximum biomass yield and astaxanthin content were 3.3 g/L and 16.7 mg/g, respectively, after 29 days of bioprocess. Astaxanthin biosynthesis was also affected by salinity, but less than other parameters. Astaxanthin bioprocess resulted in enhanced lipid yields of 35–37%, which could be used for biodiesel. This study shows promising scale-up potential with attractive sustainability features of Chlorella zofingiensis model for commercial astaxanthin-lipid biorefinery. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3x-nutrients resulted in maximum lutein 71.13 mg/L from Chlorella sorokiniana C16. • 10 k lux light exhibited the best microalgae growth, biomass, and lutein yields. • The maximum 27% lipid accumulation was obtained at 75% salinity. • 32 °C temperature was determined for the maximum lutein content 17.4 mg/g DCW. • Two-stage optimized bioprocess boosts lutein production with minimal biomass loss. The current work aims to isolate high lutein-producing microalgae and maximize lutein production under a sustainable lutein-lipid biorefinery scheme. Lutein reduces retinitis, macular degeneration risk and improves eye health. An effective bioprocess design optimized nutrients, temperature, light, and salinity for biomass and lutein yield enhancement. 3X macro/micronutrients maximally enhanced biomass and lutein yields, 5.2 g/Land 71.13 mg/L. Temperature 32 °C exhibited maximum 17.4 mg/g lutein content and 10 k lux was most favorable for growth and lutein yield (15.47 mg/g). A 25% seawater addition led maximum of 21–27% lipid that could be used for biodiesel. Isolate was identified as Chlorella sorokiniana C16, which exhibited one of the highest lutein yields reported among recent studies, positioning it as a promising candidate for commercial lutein production. This study provides valuable insights into an effective bioprocess design and highlights the C16 strain potential as a sustainable platform for high-value lutein production under a biorefinery scheme. [ABSTRACT FROM AUTHOR]

[Display omitted] • SCP and lipid were coproduced from wheat straw and (NH 4) 2 SO 4 by oleaginous yeast. • Engineered Trichosporon cutaneum MP11 with excellent adaptability was employed. • The cellulosic SCP and lipid titer reached 24.4 ± 1.5 g/L and 11.8 ± 1.2 g/L at 48 h. • Residual (NH 4) 2 SO 4 in wastewater was recycled with stable fermentation performance. Co-production of single cell protein (SCP) and lipid from lignocellulose-derived carbohydrates and inorganic ammonia offers a promising alternative for poultry or aquaculture feeds. An engineered oleaginous yeast Trichosporon cutaneum MP11 showed great potential for producing SCP and lipid from wheat straw and ammonia sulfate with minimum nutrient input. Trichosporon cutaneum MP11 showed stronger SCP and lipid fermentability using dry acid pretreated and biodetoxified wheat straw than using pure sugars. The residual ammonium sulfate in fermentation broth was recycled up to five times, resulting in ∼70% of nitrogen fixation into SCP. The overall yield of SCP and lipid from lignocellulose-derived sugars was 0.15 g/g and 0.11 g/g, respectively. This translates to the production of one ton of SCP (0.56 ton) and lipid (0.44 ton) from 6.6 tons of wheat straw, or one ton of SCP and lipid containing yeast cells (dry) from 4.8 tons of wheat straw. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chaperone and CRISPRi were first applied in algae under thermophilic condition. • Transcriptional result depicts temperature and CRISPRi effects on algal metabolism. • PGi strain showed 2.56 g/L, 23.5 and 893 mg/L of biomass, lutein and lipid at 35°C. • Thermophilic conditions affect the biomass, lipid, and CO 2 uptake in microalgae. • PGi strain had 1.08 g-CO 2 /g-DCW of CO 2 assimilation ability in mixotrophic culture. Microalgae are widely recognized as a promising bioresource for producing renewable fuels and chemicals. Microalgal biorefinery has tremendous potential for incorporation into circular bioeconomy, including sustainability, cascading use, and waste reduction. In this study, genetic engineering was used to enhance the growth, lipid and lutein productivity of Chlamydomonas reinhardtii including strains of CC400, PY9, pCHS, and PG. Notably, CRISPRi mediated on phosphoenolpyruvate carboxylase (PEPC 1) gene to down-regulate the branch pathway from glycolysis to partitioning more carbon flux to lipid was explored under meso -thermophilic condition. The best chassis PGi, which has overexpressed chaperone GroELS and applied CRISPRi resulting in the highest biomass of 2.56 g/L and also boosted the lipids and lutein with 893 and 23.5 mg/L, respectively at 35°C. Finally, all strains with CRISPRi exhibited higher transcriptional levels of the crucial genes from photosynthesis, starch, lipid and lutein metabolism, thus reaching a CO 2 assimilation of 1.087 g-CO 2 /g-DCW in mixotrophic condition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnesium aminoclay (MgA) induces CO 2 absorption and oxidative stress. • The effect of MgA on growth and lipid accumulation is Chlorella strain-dependent. • MgA improved the total lipid content and hexane extractability of Chlorella KR-1. • MgA promoted triacylglycerol biosynthesis but reduced cell wall thickness. Magnesium aminoclay nanoparticles (MgANs) exert opposing effects on photosynthetic microalgae by promoting carbon dioxide (CO 2) uptake and inducing oxidative stress. This study explored the potential application of MgAN in the production of algal lipids under high CO 2 concentrations. The impact of MgAN (0.05–1.0 g/L) on cell growth, lipid accumulation, and solvent extractability varied among three tested oleaginous Chlorella strains (N113, KR-1, and M082). Among them, only KR-1 exhibited significant improvement in both total lipid content (379.4 mg/g cell) and hexane lipid extraction efficiency (54.5%) in the presence of MgAN compared to those of controls (320.3 mg/g cell and 46.1%, respectively). This improvement was attributed to the increased biosynthesis of triacylglycerols and a thinner cell wall based on thin-layer chromatography and electronic microscopy, respectively. These findings suggest that using MgAN with robust algal strains can enhance the efficiency of cost-intensive extraction processes while simultaneously increasing the algal lipid content. [ABSTRACT FROM AUTHOR]

[Display omitted] • Exogenous GAs promoted the metabolism of SMX by C. vulgaris. • When the GAs dose reached 50 mg/L, 91.8 % of SMX was removed. • GAs promoted the production of lipid by microalgae under antibiotic stress. • GAs promoted C. vulgaris to increase antioxidant enzyme activity under SMX stress. • Transcriptome analysis revealed the molecular mechanism of GAs action. In this study, the phytohormone gibberellins (GAs) were used to enhance sulfamethoxazole (SMX) removal and lipid accumulation in the microalgae Chlorella vulgaris. At the concentration of 50 mg/L GAs, the SMX removal achieved by C. vulgaris was 91.8 % while the lipid productivity of microalga was at 11.05 mg/L d-1, which were much higher than that without GAs (3.5 % for SMX removal and 0.52 mg/L d-1 for lipid productivity). Supplementation of GAs enhanced the expression of antioxidase-related genes in C. vulgaris as a direct response towards the toxicity of SMX. In addition, GAs increased lipid production of C. vulgaris by up-regulating the expression of genes related to carbon cycle of microalgal cells. In summary, exogenous GAs promoted the stress tolerance and lipid accumulation of microalgae at the same time, which is conducive to improving the economic benefits of microalgae-based antibiotics removal as well as biofuel production potential. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stable performance was achieved in treating 10% to 14% high-solid lipids and FW. • High lipid removal owing to over 95% degradation and 100% membrane rejection. • The co-digestion of lipid and FW achieved significant biogas production. • The membrane fouling rate was decreasing with lipids ratio increasing. The co-digestion performance of mesophilic (37℃) hollow fiber anaerobic membrane bioreactor (HF-AnMBR) in treating high-solid lipids and food waste (FW) for 180 days was investigated. The organic loading rate (OLR) was increased from 2.33 to 14.64 g-chemical oxygen demand (COD) /L/d by increasing the lipids/FW from 10%, 30%, and 50% on dry based. The COD conversion efficiency for methane was 83.13%, 84.85%, 82.63%, and 84.30%, and the sludge growth rate was 0.001, 0.097, 0.065, 0.016 g TS/g COD at OLR of 2.33, 9.36, 12.76 and 14.64 g-COD/L/d, respectively. The COD, proteins, and carbohydrates concentrations in permeate were stable, with an average of 2.25, 0.50, and 0.18 g/L, respectively. The long-term stable performance of the HF-AnMBR indicated that this study will help guide application of the co-digestion of lipids and food waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrasound (US) effects during P. marina and C. zofingiensis growth were evaluated. • For P. marina , US treatment did not result in an increase of cell proliferation. • For C. zofingiensis , discontinuous US increased biomass concentration in 64 %. • Distinct behaviors may be related to differences in microalgae cell wall structures. • Carotenoid, chlorophyll, lipid, and protein contents were affected by US treatment. The present work evaluated the ultrasound (US) effects on the growth of Pseudoneochloris marina and Chlorella zofingiensis. For P. marina , US treatment did not increase cell proliferation and reduced cell density when used for 60 min (exponential phase, for 5 days), indicating a possible occurrence of cell damage. For C. zofingiensis , the application of discontinuous US for 10 min resulted in an increase of 65 % in biomass concentration compared to the control. These distinct behaviors indicate that microalgae species react differently to physical stimuli. After US treatment, a reduction of carotenoid, chlorophyll, lipid and protein concentrations was observed, which may be related to changes in the metabolic pathways to produce these compounds. Overall, the results of the present study show the potential of discontinuous US to enhance microalgae cell proliferation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Soy hulls are a significant source of cellulose and hemicellulose. • Lipomyces starkeyi LPB 53 consumed 65% of the xylose and 99% of the glucose. • Maximum accumulation of lipids by the yeast was 42.5% • Microbial oil was composed of fatty acids with 16 and 18 carbons chains. Soybean hulls are lignocellulosic residues generated in the industrial processing of soybean, representing about 5 % of the mass of the whole bean. This by-product is an important source of polymers such as cellulose (34 %) and hemicellulose (11 %), which could be valorized via biotechnology to improve the economic return of the oilseed chain. In the present work, soybean hulls were evaluated as a carbon source for biolipid production by Lipomyces starkeyi LPB 53. Initially the hulls were treated physicochemically and enzymatically to obtain fermentable sugars. Subsequently, biomass growth was evaluated using different nitrogen sources and the lipid production was optimized, reaching a maximum cell biomass concentration of 26.5 g/L with 42.5 % of lipids. Around 65 % of the xylose content was consumed. The obtained oil was majorly composed of oleic, palmitic, palmitoleic, linoleic and stearic fatty acids in a proportion of 54 %, 32 %, 4 %, 3 % and 2 %, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • 91.51 % of DFS was removed by C. sorokiniana within 9 days. • DFS promoted microalgal growth by 12.83% (DCW). • DFS enhanced chlorophylls (28.6%), carotenoids (27.6%), and lipids (30.2%). • Increased level of SFA and MUFA upon DFS removal. • Metabolomics & enzyme assays elucidated the mechanism of DFS removal. The aim of this work was to assess the efficiency of freshwater green microalga, Chlorella sorokiniana for diclofenac sodium (DFS) removal, and metabolic response of alga to comprehend the metabolic pathways involved/affected during DFS decontamination. Results showed 91.51 % removal of DFS could be achieved within 9 days of algal treatment along with recovery of enhanced value-added bioresources i.e. chlorophyll, carotenoids, and lipids from the spent biomass. DFS also had an effect on enzyme activity including superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation (MDA). Furthermore, metabolomics profiling provided an in-depth insight into changes in the metabolic response of C. sorokiniana wherein DFS induced 32 metabolites in microalgae compared to unexposed-control. This study offers microalgae as a green option for DFS removal, and the metabolomics study complemented with DFS could be an approach to understand the stress-induced strategies of C. sorokiniana for concomitant value-added products recovery in presence of DFS. [ABSTRACT FROM AUTHOR]

[Display omitted] • Significant differences in cultivable yeast diversity between different honeycombs. • R. toruloides was isolated from honeybee-related products for the first time. • Lipid concentration and biomass reached 24.41 g/L and 36.78 g/L from 120 g/L glucose. • Biodiesel yield achieved as high as 93.15% from R. toruloides C23. • Transcriptome revealed hub genes involved in high biomass and high lipid production. Oleaginous yeasts-derived microbial lipids provide a promising alternative feedstock for the biodiesel industry. However, hyperosmotic stress caused by high sugar concentration during fermentation significantly prevents high cell density and productivity. Isolation of new robust osmophilic oleaginous species from specific environment possibly resolves this issue to some extent. In this study, the cultivable yeast composition of honeycombs was investigated. Totally, 11 species of honeycomb-associated cultivable yeast were identified and characterized. Among them, an osmophilic yeast strain, designated as Rhodotorula toruloides C23 was featured with excellent lipogenic and carotenogenic capacity and remarkable cell growth using glucose, xylose or glycerol as feedstock, with simultaneous production of 24.41 g/L of lipids and 15.50 mg/L of carotenoids from 120 g/L glucose in 6.7-L fermentation. Comparative transcriptomic analysis showed that C23 had evolved a dedicated molecular regulation mechanism to maintain their high simultaneous accumulation of intracellular lipids and carotenoids and cell growth under high sugar concentration. [ABSTRACT FROM AUTHOR]

[Display omitted] • It is the very first-time that a pilot was used to accumulate lipids from sewage. • Microthrix parvicella can be used to enhance the lipid accumulation in urban sewage. • 3rd generation biofuels can be produced from accumulated lipids in urban sewage. • Lipid-pilot is a promising technology for biodiesel production from urban sewage. Wastewater treatment plants (WWTPs) may play a crucial role in shifting to a zero-emission future by becoming more sustainable and contributing to the circular economy (CE). Recovered lipids from urban sewage can serve as a raw material for biofuel production contributing to a waste reduction, mitigation of natural resources depletion and reinforcing security and energy independence. A novel, pilot-scale lipid accumulation technology (LAT) employing parameters to select M. parvicella for the biofuel/biodiesel production was implemented on a side stream of an urban WWTP. The LAT proved its concept as the average amount of extracted lipids accumulated in the bioreactors was three-fold higher when compared to the lipids existing in activated sludge. The average transesterification of extracted lipids to biodiesel resulted in a 1.6 % yield, meaning that from 1 kg of dried sludge, 16 g of biodiesel could be formed. The biodiesel produced complies with European standard specifications (EN14214). [ABSTRACT FROM AUTHOR]

[Display omitted] • Microalgal represents 3G feedstock for renewable fuels, chemical and energy production. • Green pretreatment/ extraction processes for sugars, lipids and proteins have been outlined. • Aqueous biphasic systems with suitable cations/ anions may promote high extraction yield. • Integrated microalgal biorefinery development will enhance bioresource recovery. • Biodegradability and recyclability are core areas that need to explore for scale-up activity. Microalgae enable fixation of CO 2 into carbohydrates, lipids, and proteins through inter and intracellularly biochemical pathways. These cellular components can be extracted and transformed into renewable energy, chemicals, and materials through biochemical and thermochemical transformation processes. However, recalcitrant cell wall and lack of environmentally benign efficient pretreatment processes are key obstacles in the commercialization of microalgal biorefineries. Thus, current article describes the microalgal chemical structure, type, and structural rigidity and summarizes the traditional pretreatment methods to extract cell wall constituents. Green solvents such as ionic liquid (ILs), deep eutectic solvents (DES), and natural deep eutectic solvents (NDESs) have shown interesting solvent characteristics to pretreat biomass with selective biocomponent extraction from microalgae. Further research is needed in task-specific IL/DES design, cation–anion organization, structural activity understanding of ILs-biocomponents, environmental toxicity, biodegradability, and recyclability for deployment of carbon–neutral technologies. Additionally, coupling the microalgal industry with biorefineries may facilitate waste management, sustainability, and gross revenue. [ABSTRACT FROM AUTHOR]

• VFA accumulation peaked at 1.5 day SRT (0.48 ± 0.01 g COD VFA /g TCOD FED) • VFA yield improved but solids destruction efficiency declined with shortened SRT. • VFA accumulation peaked at 20 % lipid content (0.39 ± 0.06 g COD VFA /g TCOD FED) • Lipid content >20 % DS led to major process instability and raised biogas production. • VFA accumulation and solids destruction depends on particulate matrix of the feed. • OLR and variability in food waste composition largely caused high VFA accumulation. The bioconversion of food waste to renewable products has an important role in alleviating the environmental burden of food wastage. This study evaluates the effect of solids retention time (1.5, 4, and 7 days) and lipid content (up to 30 % DS) on the solid's destruction efficiency and VFA yield from food waste fermentation. Although SRT below 4 days and lipid content beyond 20 % reduced the solids destruction efficiency (SRT −12 %, lipids −13 %), the VFA yield improved (SRT 0.36 to 0.48 g COD VFA /TCOD FED ; lipids 0.17 to 0.39 g COD VFA /TCOD FED). This appeared to be a mechanism of improved acidification which doubled to 0.77 g COD VFA /g SCOD at 1.5-day SRT. The introduction of easily degradable organics in waste oils and methanogen inhibition by LCFAs were likely causes of process instability when lipids >20 %. Further research is needed considering the COD fractionation of the feed to maximize recoverable products on a commercial scale. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phytohormones increased the growth rate of microalgae under salt stress. • Phytohormones further increased the microalgal lipid content based on salt stress. • 2 g/L salt and ABA increased lipid productivity to 3.7 times that of control. • DEGs of microalgae were mainly up-regulated under phytohormones except BL. • The regulation of different phytohormones is related to homologous recombination. In this study, a novel method of coupling phytohormones with saline wastewater was proposed to drive efficient microalgal lipid production. All the six phytohormones effectively promoted microalgae growth in saline wastewater, and further increased the microalgal lipid content based on salt stress, so as to achieve a large increase in microalgal lipid productivity. Among the phytohormones used, abscisic acid had the most significant promoting effect. Under the synergistic effect of 20 g/L salt and 20 mg/L abscisic acid, the microalgal lipid productivity reached 3.7 times that of the control. Transcriptome analysis showed that differentially expressed genes (DEGs) of microalgae in saline wastewater were mainly up-regulated under the effects of phytohormones except brassinolide. Common DEGs analysis showed that phytohormones all regulated the expression of genes related to DNA repair and substance synthesis. In conclusion, synergistic effect of salt stress and phytohormones can greatly improve the microalgal lipid production efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Myo -inositol (MI) application promotes astaxanthin and lipid coaccumulation. • MI upregulated carotenogenesis- and lipogenesis-associated genes and ethylene levels. • MI alleviated oxidative stress by increasing the levels of antioxidant enzymes. • Ethylene signalling had a positive effect on astaxanthin synthesis under MI induction. In the present study, exogenous myo -inositol (MI) was applied to induce natural astaxanthin and biolipid accumulation in Haematococcus pluvialis. Under 200 μM MI, algal cells exhibited 62.11 % and 34.67 % increases in astaxanthin and lipid content, respectively, compared to the control. The carotenogenesis and lipogenesis genes were upregulated by induction of MI. Interestingly, MI addition elevated the ethylene (ETH) content and activated antioxidant enzyme-associated gene levels, which could be involved in alleviating oxidative stress. Further data showed that the ETH signal played a positive function in stimulating astaxanthin biosynthesis under MI induction. Supplementation with ethephon plus MI boosted the astaxanthin content to 33.08 ± 0.03 mg g−1 by further upregulating astaxanthin biosynthesis genes and blocking reactive oxidative species (ROS) levels, and vice versa under ETH inhibition. This study provides a potential induction approach for natural astaxanthin production and explains the role of ethylene signalling in regulating astaxanthin synthesis by H. pluvialis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chlorella is an excellent lipid resource for biofuels and biorefineries. • Recent advances in cell disruption and lipid extraction methods updated. • Synergistic combination of physicochemical and biological methods is promising. • One-pot multiproduct extraction using green chemicals at low energy is required. Chlorella is a promising microalga for CO 2 -neutral biorefinery that co-produces drop-in biofuels and multiple biochemicals. Cell disruption and selective lipid extraction steps are major technical bottlenecks in biorefinement because of the inherent robustness and complexity of algal cell walls. This review focuses on the state-of-the-art achievements in cell disruption and lipid extraction methods for Chlorella species within the last five years. Various chemical, physical, and biological approaches have been detailed theoretically, compared, and discussed in terms of the degree of cell wall disruption, lipid extractability, chemical toxicity, cost-effectiveness, energy use, scalability, customer preferences, environment friendliness, and synergistic combinations of different methods. Future challenges and prospects of environmental-friendly and efficient extraction technologies are also outlined for practical applications in sustainable Chlorella biorefineries. Given the diverse industrial applications of Chlorella , this review may provide useful information for downstream processing of the advanced biorefineries of other algae genera. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of carbohydrates ratios on Rhodosporidium toruloides -1588 was studied. • Hydrolysate to crude glycerol ratio of 60:40 resulted in 49% lipid accumulation. • Scale-up to bench scale fermenter led to 56.3% lipid accumulation in 50% less time. • Fatty acids can be used as feedstock for food, pharmaceutical, biofuel industries. • Wood hydrolysate and glycerol are sustainable alternative substrates. Wood hydrolysate has been regarded as sustainable and renewable substrate to produce microbial lipids, a potential feedstock for the biodiesel industry. Moreover, the major by-product of biofuel industries is crude glycerol but its implementation as a carbon source is still constrained due to the presence of impurities resulting in low biomass production and low lipid titer. Thus, this study investigates the effect of different carbon ratios of hydrolysate and crude glycerol on R. toruloides -1588. Hydrolysate to crude glycerol ratio of 60:40 resulted in maximum lipid accumulation of 49% (w/w), more than 90% of sugars and glycerol consumption. Further, scale-up to bench-scale fermenter resulted in 12% higher lipid accumulation (56.3% w/w , 0.15 g/L∙h) in 50% less time than flask fermentation. Hence, the ability of R. toruloides -1588 to flourish on different carbohydrates and accumulate high lipid content will be beneficial for the further development of biorefinery industries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phaffia rhodozyma was evaluated as a potential source of bioproducts. • Recovery and fractionation of astaxanthin, β-carotene, proteins and lipids. • Integration of a sequential operations in a biorefinery approach. • Carotenoids to produce sustainable bioactive plastics. Carotenoids over-producing yeast has become a focus of interest of the biorefineries, in which the integration of the bioproduction with the following downstream processing units for the recovery and purification of carotenoids and other value-added byproducts is crucial to improve the sustainability and profitability of the overall bioprocess. Aiming the future implementation of Phaffia rhodozyma -based biorefineries, in this work, an integrative process for fractionation of intracellular compounds from P. rhodozyma biomass using non-hazardous bio-based solvents was developed. After one-extraction step, the total amount of astaxanthin, β-carotene, lipids and proteins recovered was 63.11 µg/g DCW , 42.81 µg/g DCW , 53.75 mg/g DCW and 10.93 mg/g, respectively. The implementation of sequential back-extraction processes and integration with saponification and precipitation operations allowed the efficient fractionation and recovery (% w/w) of astaxanthin (∼72.5 %), β-carotene ∼90.17 %), proteins (21.04 %) and lipids (23.72 %). After fractionation, the manufacture of carotenoids-based products was demonstrated, through the mixture of carotenoids-rich extracts with bacterial cellulose to obtain biologically active bioplastics. [ABSTRACT FROM AUTHOR]

• pH and Si variations have strong impact on metabolite production in marine diatoms. • Chlorophyll and carotenoid content increased with increasing silicate concentration. • Metabolites enhanced with increased in silica concentrations and decreased in pH. Diatom algae are increasingly explored as an alternative sustainable source for functional biomolecules likes fucoxanthin, and eicosapentaenoic acid. But biomolecule quantity and quantity are influenced by growth conditions. So, effect of differential silica concentration (0–120 mg L-1) and medium pH (5.5–9.5) on growth and cellular biochemical composition of commercially important marine diatom species were studied. Growth rate of Thalassiosira sp., Skeletonema sp., and Chaetoceros sp. , was higher with 30 mg L-1 Si at a pH of 7.5–8.5. Highest carbohydrate (153.71 mg g−1) and protein (17.34 mg g−1) content was found in Skeletonema sp. Silica concentration positively influenced chlorophyll and carotenoid content in a dose dependent manner. A medium pH of 8.5 and Si concentration between 60 and 120 mg L-1 was ideal for lipid production. The optimum concentration of Si and pH for maximum biomolecule production have been reported with further scope of utilizing these conditions in commercial scale systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lipid synthesis by oleaginous yeasts is a promising alternative to vegetable oils. • Y. lipolytica can bioconvert mixed C 2 -C 6 VFAs from gas fermentation into lipids. • Yarrowia lipolytica shows preference for acetic acid over butyric and caproic acids. • Y. lipolytica used the VFA mixture at a rate of 0.664 g/L·h with lipid accumulation. • The lipid profile obtained shows its high suitability for biodiesel production. Volatile fatty acids (VFAs) can be considered as low-cost carbon substrates for lipid accumulation by oleaginous yeasts. This study demonstrates that a common mixture of VFAs, typically obtained from the anaerobic fermentation of C1-gases by some acetogenic bacteria, can be used in a second aerobic fermentation with the yeast Yarrowia lipolytica to obtain lipids as precursors of biodiesel. In the batch experiments, the preference of Yarrowia lipolytica W29 for acetic acid over butyric and caproic acids was demonstrated, with the highest consumption rate reaching 0.664 g/L·h. In the bioreactor experiments, the amount initial biomass inoculated, as well as the initial acid concentration, were found to have a significant influence on the process. Though the lipid content was relatively low, it can be optimized and further improved. Oleic, linoleic and palmitic acids accounted for about 80 % of the fatty acids in the lipids, which makes them suitable for biodiesel. [ABSTRACT FROM AUTHOR]

[Display omitted] • Algal growth was boosted by various forms of sulfur with different dose dependent. • Effect of nitrogen on carbon assimilation in cells was regulated by sulfur form. • Sulfate was more beneficial to increase lipid productivity than other form. • Sulfur induced changes in expression of genes encoding lipid-related enzymes. Algal biodiesel has been becoming a focus in the field of bioenergy worldwide. In this study, effects of heterogeneous sulfur (SO 4 2-, SO 3 2- and S2-) on growth and lipid accumulation of Scenedesmus obliquus cultured in wastewater with a C/N ratio of 30 were investigated, respectively. The results shown that SO 4 2-, the optimal sulfur source, could trigger cell growth in a concentration-dependent manner. However, SO 3 2- was superior to the others in boosting carbon uptake of cells, which was subject to NH 4 +-N concentration. Only SO 4 2- could simultaneously increase lipid content and productivity of cells with a dominant component of oleic acid (C18:1n9c) occupying approximately 40% in fatty acid profile. Additionally, the genes encoding enzymes such as CDIPT, ADPRM, DPP1, pmtA and BTA1 involved in the uppermost lipid-related pathway (glycerophospholipid metabolism) were identified facing different sulfur source regardless of the concentration changes. These findings may facilitate nutrition management efforts to enhance microalgae-based biofuel production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chlorella sorokiniana cultivation under photoautotrophic or heterotrophic conditions. • Higher lipids (3.19 ± 0.23 g/L) at C/N 60 after 72 h growth on heterotrophic mode. • Autotrophic cultivation favored proteins (416.66 mg/g CDW) & lutein (6.40 mg/g CDW) • Total Carbohydrates for photoautotrophic (6.39 %) and heterotrophic (8.66 %) modes. • The lipid profile was suitable for its application in biodiesel production. Biorefineries enable the circular, sustainable, and economic use of waste resources if value-added products can be recovered from all the generated fractions at a large-scale. In the present studies the comparison and assessment for the production of value-added compounds (e.g., proteins, lutein, and lipids) by the microalga Chlorella sorokiniana grown under photoautotrophic or heterotrophic conditions was performed. Photoautotrophic cultivation generated little biomass and lipids, but abundant proteins (416.66 mg/g CDW) and lutein (6.40 mg/g CDW). Heterotrophic conditions using spruce hydrolysate as a carbon source favored biomass (8.71 g/L at C/N 20 and 8.28 g/L at C/N 60) and lipid synthesis (2.79 g/L at C/N 20 and 3.61 g/L at C/N 60) after 72 h of cultivation. Therefore, heterotrophic cultivation of microalgae using spruce hydrolysate instead of glucose offers a suitable biorefinery concept at large-scale for biodiesel-grade lipids production, whereas photoautotrophic bioreactors are recommended for sustainable protein and lutein biosynthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nordic microalgae produce compounds of high value when exposed to abiotic stress. • Light stress stimulates carotenoid production up to 44 mg L−1 in Desmodesmus sp. • Combined light and salt stress enhanced the lipid content by 43% of DW. • Nordic microalgae grown in various wastewaters can produce carotenoids and lipids. Nordic Desmodesmus microalgal strains (2–6) and (RUC-2) were exposed to abiotic stress (light and salt) to enhance lipids and carotenoids. The biomass output of both strains increased by more than 50% during light stress of 800 μmol m−2 s−1 compared to control light. The biomass of Desmodesmus sp. (2–6) contained most lipids (15% of dry weight) and total carotenoids (16.6 mg g−1) when grown at moderate light stress (400 μmol m−2 s−1), which further could be enhanced up to 2.5-fold by salinity stress. Desmodesmus sp. (RUC-2) exhibited maximal lipid (26.5%) and carotenoid (43.8 mg L−1) content at light intensities of 400 and 100 μmol m−2 s−1, respectively. Salinity stress stimulated lipid accumulation by 39%. Nordic Desmodesmus strains therefore are not only able to tolerate stress conditions, but their biomass considerably improves under stress. These strains have high potential to be used in algal bio-factories on low-cost medium like Baltic seawater. [ABSTRACT FROM AUTHOR]

[Display omitted] • The combined application of SA and NaSH heightened astaxanthin and lipid yields. • SA and NaSH induction upregulated growth and carotenogenesis gene expression levels. • Cellular H 2 S mediated ROS signal transduction and enzymatic antioxidant levels. To obtain higher yield of natural astaxanthin, the present study aims to develop a viable and economic induction strategy for astaxanthin production comprising succinic acid (SA) combined with sodium hydrosulfide (NaHS). The biomass (1.33 g L-1), astaxanthin concentration (44.96 mg L-1), astaxanthin content (163.55 pg cell−1), and lipid content (55.34%) were achieved under 1.0 mM SA and 100 μM NaHS treatment. These results were concomitant with enhanced hydrogen sulfide (H 2 S) but diminished reactive oxide species (ROS). Further study discovered that endogenous H 2 S could improve astaxanthin and lipid coproduction under SA induction by mediating related gene transcript levels and ROS signalling. Additionally, the concentrations of biomass and astaxanthin increased to 2.14 g L-1 and 66.25 mg L-1, respectively, under the induction of SA and NaHS in a scaled-up bioreactor. Briefly, the work proposed a novel feasible strategy for high yields of biomass and astaxanthin by H. pluvialis. [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]

[Display omitted] • High antioxidant activity hydrolysates were obtained by enzymatic hydrolysis. • Radical scavenging activities were: DPPH 33.5%; OH• 46.8%; ORAC 7.4 µmol TE/µmol. • Enzymatic treatment reduces the amount of lipid leaching reagent by 35.34–45.49%. • Modified methods help to increase the amount and variety of extracted lipids. • Comprehensive utilization of algae can be achieved through enzymatic hydrolysis. Chlorella can produce large amounts of lipids and therefore has great potential for biodiesel production. In this study, Chlorella protothecoides was hydrolyzed by several kinds of extracellular bacterial proteases produced by Pseudoalteromonas sp. ZB23-2, B27-3 and JS4-1 before lipid extraction. Hydrolysates with high antioxidant activity were obtained. The scavenging activities of 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydrogen peroxide, and hydroxyl free radicals reached 33.47 ± 0.68%, 46.81 ± 2.38%, and 7.35 ± 0.37 µmol·TE/µmol, respectively. Likewise, proteolysis reduced biomass, which resulted in a reduction in lipid leaching reagents by 35.34–45.49%. Compared to the commonly used Kates and Paradis method (171.77 ± 2.50 mg/g), the modified ethanol lipid extraction combined with JS4-1 enzyme pretreatment (291.06 ± 1.70 mg/g) and acetone-ethanol lipid extraction combined with B27-3 protease pretreatment (277.20 ± 3.30 mg/g) resulted in a larger and more diverse lipid extraction. Protease pretreatment combined with less toxic solvents for lipid extraction improved microalgal biorefinery and reduced environmental pollution. [ABSTRACT FROM AUTHOR]