Enhanced Lipid Production Research Articles

Genome-wide identification of XsDGAT family and their expression patterns in yellowhorn (Xanthoceras sorbifolium)

Diacylglycerol acyltransferase (DGAT) plays a pivotal role in lipid metabolism, particularly in the biosynthesis of triacylglycerols (TAGs), which are essential for energy storage and cellular membrane formation. Xanthoceras sorbifolium, commonly known as yellowhorn, is notable for the high oil content of its seeds and its potential in biodiesel production. However, its DGATs have not been thoroughly studied. In this study, we conducted the bioinformatics analysis of the XsDGAT gene family in X. sorbifolium. The XsDGAT homologs, sequence features, domain architecture, and evolutionary relationships were identified, the expression patterns across different tissues and their potential regulatory elements of XsDGATs were also displayed, providing valuable insights into their potential roles in lipid biosynthesis and accumulation. This comprehensive bioinformatics analysis offers valuable resources for further experimental investigations and potential applications aimed at enhancing lipid productivity in X. sorbifolium.

Regulating the metabolic flux of pyruvate dehydrogenase bypass to enhance lipid production in Saccharomyces cerevisiae

To achieve high efficiency in microbial cell factories, it is crucial to redesign central carbon fluxes to ensure an adequate supply of precursors for producing high-value compounds. In this study, we employed a multi-omics approach to rearrange the central carbon flux of the pyruvate dehydrogenase (PDH) bypass, thereby enhancing the supply of intermediate precursors, specifically acetyl-CoA. This enhancement aimed to improve the biosynthesis of acetyl-CoA-derived compounds, such as terpenoids and fatty acid-derived molecules, in Saccharomyces cerevisiae. Through transcriptomic and lipidomic analyses, we identified ALD4 as a key regulatory gene influencing lipid metabolism. Genetic validation demonstrated that overexpression of the mitochondrial acetaldehyde dehydrogenase (ALDH) gene ALD4 resulted in a 20.1% increase in lipid production. This study provides theoretical support for optimising the performance of S. cerevisiae as a “cell factory” for the production of commercial compounds.

Unveiling significant roles of phytohormone 6-benzylaminopurine in empowering Phaeodactylum tricornutum for high-salinity wastewater treatment and bioresource recovery

High-salinity presents significant challenges in microalgal wastewater treatment and bioresource recovery due to salinity stress. This study explored the use of salt-tolerant microalgae in conjunction with phytohormone regulation. 1 µM 6-benzylaminopurine increased the biomass of Phaeodactylum tricornutum by 38.3 % and enhanced lipid production by 36.8 %. 6-benzylaminopurine significantly improved the removal of inorganic carbon, total nitrogen, and total phosphorus by 85.2 %, 27.4 %, and 31.9 %. Specifically, 6-benzylaminopurine improved K+ transportation by 71.0 %, increased the activity of Ca2+ transport ATPase and Ca2+ sensors by 49.0 %–83.0 %, optimized osmotic balance, and alleviated salt-induced damage. The contents of proline and extracellular polymers increased by 34.8 % and 35.5 %. A 38.4 % reduction in reactive oxygen species indicated that high-salinity stress was mitigated. The analysis of Sustainable Development Goals showed a 56.2 % improvement in Affordable and Clean Energy. Overall, these findings further highlighted the promising application of the phytohormone 6-benzylaminopurine in microalgal high-salinity wastewater treatment and lipid production.

Use of plant growth regulators and their combined application to enhance lipid productivity in the filamentous microalga Tribonema sp.

Oleaginous Tribonema sp. has shown great potential in biodiesel production. However, effective strategies are still needed to increase overall lipid productivity for cost-effectiveness. Although the effects of plant growth regulators (PGRs) on enhancing microalgal growth and lipid content have been widely demonstrated, the synergistic effects of their combinations on improving lipid productivity in Tribonema sp. remain unclear. In this study, we investigated the comparative effects of five PGRs (e.g., fulvic acid, melatonin, gibberellin, γ-aminobutyric acid [GABA], and indoleacetic-3-acid [IAA]) at different concentrations (0.1–10 mg/L) on the growth, nitrogen uptake, and lipid content of Tribonema sp. The results showed that 10 mg/L GABA and 0.1 mg/L IAA were optimal conditions, contributing to an approximately 33.00 % increase in lipid productivity compared with the control (without PGRs). Based on these findings, the combination of optimized concentrations of GABA and IAA, especially in equal proportions, resulted in a more desirable fatty acid profile and produced the highest biomass, lipid content, and lipid productivity, with increases of 23.55 %, 25.62 %, and 54.95 %, respectively, over the control. This combination also significantly increased nitrogen removal efficiency in the medium, which was 46.24 % higher that of the control. These results were attributed to the significant upregulation of genes associated with nitrogen metabolism mediated by the synergy of IAA and GABA, promoting nitrate uptake by algal cells in the medium. Genes involved in photosynthesis and lipid synthesis were also upregulated, facilitating simultaneous biomass and lipid accumulation to maximize lipid productivity. Overall, this study is the first to report the combined application of GABA and IAA as an effective strategy to enhance lipid productivity in Tribonema sp., providing insights into the underlying mechanisms. These findings offer a promising solution for economically improving microalgal lipid production.

Enhanced lipid production of Auxenochlorella pyrenoidosa using biochar-pretreated tobacco industry wastewater

Tobacco industry wastewater, containing high levels of nicotine, organic carbon, dyes, and other pollutants, presents significant environmental and health challenges. This study evaluates the combined application of wood-derived biochar and microalgal biorefineries for effective treatment of this wastewater. A 3 % biochar dosage was determined to be optimal, achieving complete nicotine removal, enhancing wastewater transmittance from 12.29 % to 88.8 %, and reducing chemical oxygen demand (COD) levels by 87.7 % to 1757.3 mg/L, creating conditions favorable for the growth of Auxenochlorella pyrenoidosa. The pretreatment preserved key nutrients, such as sugars, total nitrogen (TN), and total phosphorus (TP), which supported enhanced microalgal photosynthesis and led to significant increases in biomass and lipid accumulation, particularly in unsaturated fatty acids. This shift in lipid composition contributed to a significant reduction in the cold filter plugging point value, improving the suitability of microalgae-derived biodiesel for use in cold climates. Transcriptomic analysis revealed upregulation of pathways involved in photosynthesis, carbon fixation, and fatty acid biosynthesis, while downregulation of the tricarboxylic acid (TCA) cycle minimized acetyl-CoA consumption, further promoting lipid synthesis. This integrated approach not only effectively detoxifies tobacco industry wastewater but also converts it into valuable biofuels, offering a promising and sustainable strategy for waste management and biofuel production.

Model development and process evaluation for algal growth and lipid production

Microalgae grabbed the attention worldwide because of their application in renewable energy with a number of environmental benefits such as carbon dioxide assimilation to produce biofuel. In this study, a kinetic model aiming to analyze algae growth and lipid production was developed. Biomass was divided into two parts, algae residual cell and lipid, to analyze their kinetics distinctively and to find out the inside process mechanism. The model was calibrated and validated with different experimental datasets, varying carbon sources, and phosphate concentrations. The capability of the model to predict the dynamics of algal culture over a broad range of growth conditions was investigated. The presence of acetate reduced the bicarbonate uptake for algal growth and growth on organic carbon was higher compared to that of carbon dioxide. The presence of ammonium showed a very strong inhibition effect on algae and lipid production rate but enhanced lipid content. Phosphate caused both limitation and inhibition effects on algae growth and lipid production rate. The maximum growth was found at 12 mg/L PO43- concentration and 3.10 mg/L NO3--N concentration. Lipid content was enhanced by limiting phosphate. Overall, the developed model allows optimizing of nutrient concentrations and operating conditions specifically to enhance lipid productivity.

Regulation of carbon metabolic fluxes to enhance lipid and succinate production in oleaginous fungus Mortierella alpina.

Mortierella alpina is popular for lipid production, but the low carbon conversion rate and lipid yield are major obstacles for its economic performance. Here, external addition of organic acids involved in tricarboxylic acid cycle was used to tune carbon flux and improve lipid production. Citrate was determined to be the best organic acid that can be used for enhancing lipid production. By the addition of citrate, the lipid titer and content were approximately 1.24 and 1.34 times higher, respectively. Meanwhile, citrate supplement also promoted the accumulation of succinate, an important value-added platform chemical. Owing to the improved lipid and succinate production through adding citrate, the carbon conversion rate of M. alpina reached up to 52.17%, much higher than that of the control group (14.11%). The addition of citrate could redistribute carbon flux by regulating the expression level of genes related to tricarboxylic acid cycle metabolism. More carbon fluxes flow to lipid and succinate synthesis, which greatly improved the carbon conversion efficiency of M. alpina. This study provides an effective and straightforward strategy with potential economic benefits to improve carbon conversion efficiency in M. alpina.

Oleaginous fungi: a promising source of biofuels and nutraceuticals with enhanced lipid production strategies.

Oleaginous fungi have attracted a great deal of interest for their potency to accumulate high amounts of lipids (more than 20% of biomass dry weight) and polyunsaturated fatty acids (PUFAs), which have a variety of industrial and biological applications. Lipids of plant and animal origin are related to some restrictions and thus lead to attention towards oleaginous microorganisms as reliable substitute resources. Lipids are traditionally biosynthesized intra-cellularly and involved in the building structure of a variety of cellular compartments. In oleaginous fungi, under certain conditions of elevated carbon ratio and decreased nitrogen in the growth medium, a change in metabolic pathway occurred by switching the whole central carbon metabolism to fatty acid anabolism, which subsequently resulted in high lipid accumulation. The present review illustrates the bio-lipid structure, fatty acid classes and biosynthesis within oleaginous fungi with certain key enzymes, and the advantages of oleaginous fungi over other lipid bio-sources. Qualitative and quantitative techniques for detecting the lipid accumulation capability of oleaginous microbes including visual, and analytical (convenient and non-convenient) were debated. Factors affecting lipid production, and different approaches followed to enhance the lipid content in oleaginous yeasts and fungi, including optimization, utilization of cost-effective wastes, co-culturing, as well as metabolic and genetic engineering, were discussed. A better understanding of the oleaginous fungi regarding screening, detection, and maximization of lipid content using different strategies could help to discover new potent oleaginous isolates, exploit and recycle low-cost wastes, and improve the efficiency of bio-lipids cumulation with biotechnological significance.

Integrated lipidomic and transcriptomic analyses provide insights into the positive effect of hydrogen peroxide treatment on lipid synthesis in oleaginous red yeast Sporobolomyces pararoseus

Microbial lipids are a group of promising renewable sources that are highly demanded by the food, feed, pharmaceutical, and biofuel industries. Sporobolomyces pararoseus is a well-studied oleaginous yeast that is usually considered superior for the industrial production of microbial lipids over other conventional microorganisms. The objective of this study was to investigate the specific effect of hydrogen peroxide treatment on the biosynthesis of microbial lipids in S. pararoseus via lipidomics and transcriptomics technologies. These results showed that hydrogen peroxide treatment significantly enhanced lipid production in S. pararoseus CJR, especially the triacylglycerols. The up-regulation of several key lipogenic genes might be one of the main reasons for this enhancement. Integrative analysis of the lipidome and transcriptome revealed that some key protein-encoding genes and transcription factors might play a crucial regulatory role in lipid biosynthesis under hydrogen peroxide stress. Together, the results presented herein not only provided a feasible fermentation process for boosting the yield of certain lipids but also deepened our understanding of the lipid biosynthesis in S. pararoseus CJR. This could serve as a molecular cornerstone for enhancing their yield through genetic engineering and then further facilitate commercial applications of microbial lipids synthesized by S. pararoseus in more industrial sectors.

Contaminant removal performance and lipid productivity of a cyanobacteria-bacteria consortium containing exogenous phytohormones during the treatment of antibiotic-polluted wastewater

In this study, a cyanobacteria-bacteria consortium containing native wastewater bacteria and immobilized Synechococcus sp. was constructed. The cyanobacterial cellular responses (including growth, biomass and lipid productivity) and contaminant removal ability (for TN, TP, COD and antibiotics) in the consortium were evaluated during the advanced treatment of wastewater containing 10–50 μg/L of mixed antibiotics (amoxicillin, tetracycline, erythromycin, sulfadiazine and ciprofloxacin) with the addition of a certain phytohormone (indole-3-acetic acid, gibberellin A3 or 6-benzylaminopurine) at trace level within a period of four days. Each phytohormone promoted the growth of Synechococcus sp. and increased the tolerance of Synechococcus sp. to mixed antibiotics. Indole-3-acetic acid coupled to moderate antibiotic stress could elevate lipid productivity and lipid content of Synechococcus sp. to 33.50 mg/L/day and 43.75%, respectively. Phytohormones increased the pollutant removal performance of the cyanobacteria-bacteria consortium through the stimulation of cyanobacterial growth and the regulation of cyanobacteria-bacteria interaction, which increased the abundances of microalgae-associated bacteria including Flavobacterium, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Bosea, Sphingomonas and Emticicia. Up to 80.83%, 98.06%, 83.26%, 99.84%, 99.50%, 89.41%, 65.61% and 60.65% of TN, TP, COD, amoxicillin, tetracycline, erythromycin, sulfadiazine and ciprofloxacin were removed by the consortium with the addition of phytohormones. In general, indole-3-acetic acid was the optimal phytohormone for enhancing lipid production and contaminant removal performance of the cyanobacteria-bacteria consortium.

Elucidating the adaptive response and enhanced lipid production of Chlorella minutissima under Cr (VI) stress

The exponential surge in industrialization and urbanization witnessed in recent decades has alarmingly escalated the levels of hazardous pollutants, instigating profound apprehensions regarding environmental safety. In particular, the bioamplification of heavy metals like hexavalent chromium [Cr (VI)] being a prominent example, has not only imposed severe repercussions on human health but has also wrought havoc within the intricate balance of the ecological framework. Rectifying Cr (VI) via bioremediation agents exemplified as microalgae, emerges as an environmentally harmonious strategy. The present study delves into the intricate mechanisms underpinning the adaptive responses of a freshwater microalga, Chlorella minutissima, in the face of Cr (VI) stress. Evidencing exceptional tolerance to Cr (VI) induced stress, this microalga manifested an IC50 value of ~10 ppm while evidencing an astounding removal efficiency of ~89 %. This heightened assimilation of Cr (VI) by the microalgal cells concomitantly accompanied ~1.6 fold rise in total lipid content. The fostered levels of stress metabolites and antioxidant enzymes indicate the activation of defense mechanism to mitigate Cr (VI) induced oxidative damage. Microalgae employ reduction mechanism converting toxic Cr (VI) into the less deleterious Cr (III) where Cr2O3 and CrO (OH) were found to be the prominent species; while Cr (VI) primarily existed as CrO42−. The present study provided a detailed understanding of C. minutissima towards stress tolerance and enhanced lipid production mechanisms incited by chromium exposure.

Engineering Fatty Acid Biosynthesis in Microalgae: Recent Progress and Perspectives.

Microalgal lipids hold significant potential for the production of biodiesel and dietary supplements. To enhance their cost-effectiveness and commercial competitiveness, it is imperative to improve microalgal lipid productivity. Metabolic engineering that targets the key enzymes of the fatty acid synthesis pathway, along with transcription factor engineering, are effective strategies for improving lipid productivity in microalgae. This review provides a summary of the advancements made in the past 5 years in engineering the fatty acid biosynthetic pathway in eukaryotic microalgae. Furthermore, this review offers insights into transcriptional regulatory mechanisms and transcription factor engineering aimed at enhancing lipid production in eukaryotic microalgae. Finally, the review discusses the challenges and future perspectives associated with utilizing microalgae for the efficient production of lipids.

Enhancing lipid production in Chlorella under successive stresses of periodic micro-current and salinity: Performance and contribution

Two-stage cultivation of Chlorella with periodic micro-current coupled with NaCl stress was investigated to analyze the performance and contribution of increased lipid production. In the growth stage, periodic micro-current of 3 mA resulted in an escalation of 290.06 mg/L of Chlorella’s biomass by 61.25 % in comparison to the control. During the induction stage, under a NaCl concentration of 8 g/L, the highest lipid content and yield attained were 42.11 % and 199.32 mg/L, revealing an increment of 53.13 % and 39.11 % respectively when compared to the control. Additionally, the polyunsaturated fatty acids content (PUFA) decreased from 30.11 % to 23.09 %, while the saturated fatty acids content (SFA) increased from 31.86 % to 42.39 %. Chlorella demonstrated adaptability to the alterations in the cultivation environment by an initial upsurge and later a reduction in SOD and CAT enzyme activities, and concurrently facilitated lipid synthesis by similar changes in the activities of ACCase and DGAT. The above cultivation enabled a synergistic effect of swift growth and efficient lipid accumulation in Chlorella, providing groundwork for large-scale biofuel production.

Enhancing lipid production and sedimentation of Chlorella pyrenoidosa in saline wastewater through the addition of agricultural phytohormones

In this study, the effect of external agricultural phytohormones (mixed phytohormones) addition (1.0, 5.0, 10.0, and 20.0 mg L−1) on the growth performance, lipid productivity, and sedimentation efficiency of Chlorella pyrenoidosa cultivated in saline wastewater was investigated. Among the different concentrations evaluated, the highest biomass (1.00 g L−1) and lipid productivity (11.11 mg L−1 d−1) of microalgae were obtained at 10.0 mg L−1 agricultural phytohormones addition. Moreover, exogenous agricultural phytohormones also improved the sedimentation performance of C. pyrenoidosa, which was conducive to the harvest of microalgae resources, and the improvement of sedimentation performance was positively correlated with the amount of agricultural phytohormones used. The promotion of extracellular polymeric substances synthesis by phytohormones in microalgal cells could be considered as the reason for its promotion of microalgal sedimentation. Transcriptome analysis revealed that the addition of phytohormones upregulated the expression of genes related to the mitogen-activated protein kinase (MAPK)-mediated phytohormone signaling pathway and lipid synthesis, thereby improving salinity tolerance and lipid production in C. pyrenoidosa. Overall, agricultural phytohormones provide an effective and inexpensive strategy for increasing the lipid productivity and sedimentation efficiency of microalgae cultured in saline wastewater.

Optimization of stage conversion time and modification of cell metabolism to enhance lipid production of Auxenochlorella pyrenoidosa in two-stage cultivation

Traditionally, the time of maximum biomass concentration in stage I is the widely adopted stage conversion time in two-stage microalgae culture. This study challenges this conventional approach, demonstrating that the optimal stage conversion time in stage I is 72 h rather than 120 h for achieving maximum biomass concentration. A comparison of cell characteristics revealed that algal cells at 72 h exhibited better growth potential, leading to a higher biomass concentration after transfer to stage II and, consequently, increased lipid productivity. Moreover, the use of phosphorus repletion (5-fold) in stage II directed carbon flux toward biomass growth and lipid accumulation, thereby enhancing lipid productivity. By optimizing the stage conversion time and implementing phosphorus repletion, the mean lipid productivity of Auxenochlorella pyrenoidosa cultured under autotrophy-nitrogen starvation and autotrophy-high light conditions increased by 31 % and 60 %, respectively. This study underscores the importance of reevaluating the currently widely used stage conversion time.

Enhancing biomass and lipid production in marine microalga Dunaliella tertiolecta with physico-chemical modulation and using cheap fertilizer substrate

Enhancing biomass and lipid production in marine microalga Dunaliella tertiolecta with physico-chemical modulation and using cheap fertilizer substrate

Metabolic engineering and genome editing strategies for enhanced lipid production in microalgae

Metabolic engineering and genome editing strategies for enhanced lipid production in microalgae

Theoretical Models Constructed by Artificial Intelligence Algorithms for Enhanced Lipid Production: Decision Support Tools

Theoretical models that predict the lipid content of microalgae are an important tool for increasing lipid productivity. In this study, response surface methodology (RSM), RSM combined with artificial neural network (ANN), and RSM combined with ensemble learning algorithms (ELA) for regression were used to calculate the maximum lipid percentage (%) from Chlorella minutissima (C. minutissima). We defined one set of rules to achieve the highest lipid content and used trees.RandomTree (tRT) to simulate the process parameters under various conditions. Among the various models, results showed the optimum values of the root mean squared error (0.2156), mean absolute error (0.1167), and correlation coefficient (0.9961) in the tRT model. RSM combined with tRT estimated that the lipid percentage was 30.3% in wastewater (< 35%), lysozyme (≥ 3.5 U/mL), and chitinase (< 15 U/mL) concentrations, achieving the best model based on experimental data. The optimal values of wastewater concentration, chitinase, and lysozyme were 20% (v/v), 5 U/mL, and 10 U/mL, respectively. Also, the if-then rules obtained from tRT were also used to test the process parameters. The tRT model served as a powerful tool to obtain maximum lipid content. The final rankings of the performance of various algorithms were determined. Furthermore, the models developed can be used by the fuel industry to achieve cost-effective, large-scale production of lipid content and biodiesel.

Installing xylose assimilation and cellodextrin phosphorolysis pathways in obese Yarrowia lipolytica facilitates cost-effective lipid production from lignocellulosic hydrolysates

BackgroundYarrowia lipolytica, one of the most charming chassis cells in synthetic biology, is unable to use xylose and cellodextrins.ResultsHerein, we present work to tackle for the first time the engineering of Y. lipolytica to produce lipids from cellodextrins and xylose by employing rational and combinatorial strategies. This includes constructing a cellodextrin-phosphorolytic Y. lipolytica by overexpressing Neurospora crassa cellodextrin transporter, Clostridium thermocellum cellobiose/cellodextrin phosphorylase and Saccharomyces cerevisiae phosphoglucomutase. The effect of glucose repression on xylose consumption was relieved by installing a xylose uptake facilitator combined with enhanced PPP pathway and increased cytoplasmic NADPH supply. Further enhancing lipid production and interrupting its consumption conferred the obese phenotype to the engineered yeast. The strain is able to co-ferment glucose, xylose and cellodextrins efficiently, achieving a similar μmax of 0.19 h−1, a qs of 0.34 g-s/g-DCW/h and a YX/S of 0.54 DCW-g/g-s on these substrates, and an accumulation of up to 40% of lipids on the sugar mixture and on wheat straw hydrolysate.ConclusionsTherefore, engineering Y. lipolytica capable of assimilating xylose and cellodextrins is a vital step towards a simultaneous saccharification and fermentation (SSF) process of LC biomass, allowing improved substrate conversion rate and reduced production cost due to low demand of external glucosidase.

Enhancing lipid productivity in Nannochloropsis salina by overexpression of endogenous glycerol-3-phosphate dehydrogenase

Enhancing lipid productivity in Nannochloropsis salina by overexpression of endogenous glycerol-3-phosphate dehydrogenase