Lipid Production Research Articles

Enhancing Escherichia coli abiotic stress resistance through ornithine lipid formation

Escherichia coli is a common host for biotechnology and synthetic biology applications. During growth and fermentation, the microbes are often exposed to stress conditions, such as variations in pH or solvent concentrations. Bacterial membranes play a key role in response to abiotic stresses. Ornithine lipids (OLs) are a group of membrane lipids whose presence and synthesis have been related to stress resistance in bacteria. We wondered if this stress resistance could be transferred to bacteria not encoding the capacity to form OLs in their genome, such as E. coli. In this study, we engineered different E. coli strains to produce unmodified OLs and hydroxylated OLs by expressing the synthetic operon olsFC. Our results showed that OL formation improved pH resistance and increased biomass under phosphate limitation. Transcriptome analysis revealed that OL-forming strains differentially expressed stress- and membrane-related genes. OL-producing strains also showed better growth in the presence of the ionophore carbonyl cyanide 3-chlorophenylhydrazone (CCCP), suggesting reduced proton leakiness in OL-producing strains. Furthermore, our engineered strains showed improved heterologous violacein production at phosphate limitation and also at low pH. Overall, this study demonstrates the potential of engineering the E. coli membrane composition for constructing robust hosts with an increased abiotic stress resistance for biotechnology and synthetic biology applications.Key points• Ornithine lipid production in E. coli increases biomass yield under phosphate limitation.• Engineered strains show an enhanced production phenotype under low pH stress.• Transcriptome analysis and CCCP experiments revealed reduced proton leakage.

Abstract LB292: Glutathione supports lipid abundance in vivo

Abstract Glutathione (GSH), the most abundant antioxidant, scavenges free radicals and prevents the detrimental effects of oxidative stress. As a result, GSH levels are associated with protection from stress-related conditions, such as aging and cancer. Given this rationale, antioxidants are routinely consumed by the public, mainly because they are viewed as “cure-alls” and almost uniformly beneficial to a range of diseases. This is an oversimplification, as the relationship between antioxidants and diseases is much more complex. Recent evidence has implicated GSH in protecting cancer cells from oxidative stress and promoting their survival. Therefore, understanding GSH metabolism in vivo and its intricate crosstalk with other cellular pathways is vital to improving the efficacy of therapies for diseases, including cancer. To interrogate this, we developed a series of in vivo models to induce Gclc deletion in adult animals. We find that GSH is essential to lipid abundance in vivo. GSH levels are reported to be highest in liver tissue, which is also a hub for lipid production. While the loss of GSH did not cause liver failure, it decreased lipogenic enzyme expression, circulating triglyceride levels, and fat stores. Mechanistically, we found that GSH promotes lipid abundance via the LXR/SREBP signaling pathway, as well as by repressing NRF2, a transcription factor induced by oxidative stress. Overall, these findings suggest an essential function for GSH in maintaining circulating lipids levels and lipid depots, possibly as a mechanism to prevent lipid peroxidation and redox imbalances. Notably, the accumulation of oxidized lipids propagates oxidative stress and associated cell death phenotypes (i.e., ferroptosis). This also highlights a potentially novel mechanism by which GSH regulates lipid production and suggests a possible link between oxidative stress (caused by GSH deficiency) and cachexia (commonly characterized by loss of fat and lean mass), a disorder linked to cancer but poorly understood. Consequently, by elucidating the contributions of GSH to lipid homeostasis, we can better understand the basic biology surrounding GSH and obtain critical insight into potentially improving the treatment of cancer-related cachexia. Citation Format: Gloria Asantewaa, Emily T. Tuttle, Nathan P. Ward, Yun P. Kang, Yumi Kim, Madeline Kavanagh, Aaron R. Huber, Joshua Munger, Benjamin Cravatt, Calvin L. Cole, Gina M. DeNicola, Isaac S. Harris. Glutathione supports lipid abundance in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB292.

Key Proteomics Tools for Fundamental and Applied Microalgal Research.

Microscopic, photosynthetic prokaryotes and eukaryotes, collectively referred to as microalgae, are widely studied to improve our understanding of key metabolic pathways (e.g., photosynthesis) and for the development of biotechnological applications. Omics technologies, which are now common tools in biological research, have been shown to be critical in microalgal research. In the past decade, significant technological advancements have allowed omics technologies to become more affordable and efficient, with huge datasets being generated. In particular, where studies focused on a single or few proteins decades ago, it is now possible to study the whole proteome of a microalgae. The development of mass spectrometry-based methods has provided this leap forward with the high-throughput identification and quantification of proteins. This review specifically provides an overview of the use of proteomics in fundamental (e.g., photosynthesis) and applied (e.g., lipid production for biofuel) microalgal research, and presents future research directions in this field.

Transcriptomic profiling of an evolved Yarrowia lipolytica strain: tackling hexanoic acid fermentation to increase lipid production from short-chain fatty acids

BackgroundShort-chain fatty acids (SCFAs) are cost-effective carbon sources for an affordable production of lipids. Hexanoic acid, the acid with the longest carbon chain in the SCFAs pool, is produced in anaerobic fermentation of organic residues and its use is very challenging, even inhibiting oleaginous yeasts growth.ResultsIn this investigation, an adaptive laboratory evolution (ALE) was performed to improve Yarrowia lipolytica ACA DC 50109 tolerance to high hexanoic acid concentrations. Following ALE, the transcriptomic analysis revealed several genetic adaptations that improved the assimilation of this carbon source in the evolved strain compared to the wild type (WT). Indeed, the evolved strain presented a high expression of the up-regulated gene YALI0 E16016g, which codes for FAT1 and is related to lipid droplets formation and responsible for mobilizing long-chain acids within the cell. Strikingly, acetic acid and other carbohydrate transporters were over-expressed in the WT strain.ConclusionsA more tolerant yeast strain able to attain higher lipid content under the presence of high concentrations of hexanoic acid has been obtained. Results provided novel information regarding the assimilation of hexanoic acid in yeasts.

Intensifying outdoor cultivation of oleaginous microalgae in photobioreactors for simultaneous wastewater bioremediation and low-cost production of renewable biodiesel feedstocks

Oleaginous microalgae are gaining increasing attention for simultaneous wastewater bioremediation and biofuel feedstock production. In this study, four oleaginous species of microalgae including Chlamydomonas sp. WWP, Scenedesmus sp. HP56, Haematococcus sp., and Nannochloropsis sp., were screened for their growth and lipid production at 30, 35, and 40 °C, under light intensity at 3, 4, and 5 klux. Among the strains screened, Haematococcus sp. grew best and gave comparable high growth at 30 °C and 35 °C (0.7–0.8 g/L) indicating its thermotolerant characteristic, and the optimal light intensity was found at 4 klux. Haematococcus sp. also grew well using unsterile secondary effluent from the seafood processing plant and produced high biomass (0.53–0.57 g/L) and lipids (0.17–0.19 g/L), especially in the column photobioreactor (CP). The repeated-batch outdoor cultivation mode showed that CP equipped with four-blade baffles was most efficient for the production of biomass (0.40–0.63 g/L) and lipids (0.15–0.30 g/L) during 4 cycles. The microalga also removed total nitrogen and total phosphorus from secondary effluent by 70.59% and 94.97%, respectively. The fatty acid compositions in microalgal lipids were C16-C18, especially palmitic acid, oleic acid, and linolenic acid, which show superior fuel properties, suggesting their promising use as biodiesel feedstocks. These strategies may have a significant impact not only on bioremediation of industrial effluent but also low-cost production of microalgae-based biodiesel feedstocks.

Characterization of GPAT gene family in Euphorbia lathyris L. and elucidating the role of ElGPAT9 in the biosynthesis of oils and pollen viability

Caper spurge (Euphorbia lathyris L.), known for its high content of oleic acid-enriched seed oils, has gained recognition as a valuable non-edible feedstock for biodiesel production. However, there is limited understanding of the biosynthesis and regulation of these desirable seed oils. In this study, an omics-based approach and genetic transformation were employed to investigate the glycerol-3-phosphate acyltransferase (GPAT) enzyme, which catalyzes the initial acylation reaction in triacylglycerol (TAG) biosynthesis, in caper spurge. Ten genes encoding ElGPAT, identified from the E. lathyris genome, were classified into three phylogenetic groups, exhibiting similar protein motifs and gene structures. RNA-seq data revealed distinct expression patterns of these ElGPAT genes in various tissues and different stages of seed development. Notably, ElGPAT9 showed the highest expression in flowers and developing seeds, with its encoded protein localized in the endoplasmic reticulum. Experiments using a yeast (Saccharomyces cerevisiae) expression system demonstrated that ElGPAT9 exhibited strong GPAT enzyme activity, crucial for TAG assembly, and preference for oleic acid (C18:1), as confirmed by feeding tests with exogenous fatty acids (FA). Similarly, stable transgenic lines of Nicotiana tabacum over-expressing ElGPAT9 showed increased levels of total oil and oleic acid, as well as improved pollen viability, without any growth penalty compared to wild-type and empty-vector controls. The transcriptome based WGCNA also identified genes related to lipid synthesis that are co-expressed with ElGPAT9. These findings provide a foundation for further understanding the roles of ElGPAT family members in E. lathyris and suggest the potential of ElGPAT9 as a desirable target for genetic engineering to enhance the production of vegetable oils enriched with C18:1 in caper spurge and other oil crops, contributing to sustainable biodiesel and lipid product production.

Milk lipid and milk fat globule membrane production

The formation of the mammary secretion, proteins, lipids and ions is of fundamental importance to the dairy industry. The cellular interactions which allow secretion of protein and especially milk fat globules are still controversial. However, electron microscopy provides a basis for a straightforward scheme of secretion presented as a diagram. Each step in the process can then be defined, the published evidence for each assessed and areas which need further work clearly recognised. We also hope that the diagram will act as a way of combining global approaches such as proteomics or protein knockouts with the detail of electron microscopy.

Effect of geometrical modifications on the mixing and enzymatic conversion of structured lipids in internal-loop airlift bioreactors

Airlift bioreactors present a compelling alternative for reactions utilizing immobilized enzymes, offering advantages over stirred tank and packed-bed reactors. This study proposed a new configuration for an internal-loop airlift bioreactor (1 L working volume) to produce structured triglycerides using immobilized lipases in a viscous fluid. Different internal tube configurations were studied, which varied in diameter (17.5–78.6 mm), angle (-2,0,5,10 and 12°), and the addition of a rounded bottom to the bioreactor, which improved the three-phase mixture flow. The hydrodynamic effect caused by these modifications was evaluated by studying the mixing time. The best internal tube configuration, featuring a truncated cone-shaped, exhibited a 5° angle and a 64.5-mm diameter, resulting in a mixing time of 54 s. This value was about three times less than the mixing time obtained by the standard tube (171 s) at 2 vvm. Sequentially, grape seed oil acidolysis reactions with capric acid (C10) catalyzed by the Lipozyme RM IM were performed, obtaining structured MLM triglycerides with an incorporation degree of 32.32% ± 1.01%. These results indicated good biocatalyst operational stability, with a half-life of 14.13 days. Thus, this work unveils a new configuration for an airlift bioreactor collectively driving promising advancements in structured lipid production.

The Potential of Mucor irregularis Isolated From Fruits in Producing Microbial Lipid

In this present study, potential oleaginous Mucorales fungi that have been isolated from fruits from local markets in Sleman, Indonesia, were screened for lipid production. A total of six fungal cultures were isolated and screened using a semisynthetic medium with glucose as a carbon source and a limited nitrogen supply. The highest lipid content was observed in isolate JR 1.1, up to 43.46% and 3.28 g/L lipid yield. Therefore, it was selected for molecular identification and fatty acid analysis. The result showed that JR 1.1 was identified as Mucor irregularis. The fatty acid profile of JR 1.1 showed 16.89% palmitoleic acid, 4.85% oleic acid, 45.22% linolenic acid, 30.79% gamma-linolenic acid, and 2.25% other fatty acids. It can be concluded that M. irregularis JR 1.1 is a potential strain to be used as a lipid producer for biodiesel feedstock. Further studies are recommended to optimize lipid productivity and improve fatty acid composition.

Effect of organic carbon sources on growth, lipid production and fatty acid profile in mixotrophic culture of Scenedesmus dimorphus (Turpin) Kützing

Due to non-renewability of fossil fuels and various environmental problems associated with their use, there is a growing interest in producing biodiesel from microalgae. Finding novel microalgal strains with desired characteristics such as rapid growth rates, high lipid productivity, and suitable fatty acid compositions is important for the production of biodiesel. Comparatively, photoautotrophic cultivation of microalgae results in low biomass yields and lipid productivities. Mixotrophic and heterotrophic cultures, in contrast, lead to higher biomass and lipid productivities but their productivities are species specific and depend a lot on the organic carbon source and culture conditions. In the present study, the potential of Scenedesmus dimorphus for biodiesel oil production under mixotrophic culture was investigated. The effects of organic carbon sources (glucose, ethanol and glycerol) on growth, biomass yields, lipid contents, lipid productivities and fatty acids compositions of Scenedesmus dimorphus in mixotrophic cultures were investigated. In comparison to photoautotrophic cultures, mixotrophic cultures produced significantly higher biomass concentration, lipid content, and lipid productivities (P≤0.05) under all the cultivation conditions investigated. The maximum biomass and lipid productivities achieved by mixotrophic culture were 83.88±0.05 and 17.11±0.04 mg L−1 day−1 respectively which are more than 2.6 and 3.1 folds higher than those obtained under photoautotrophic condition. Using glucose as the organic carbon source was better than ethanol and glycerol in terms of biomass and lipid productivities (glucose > ethanol > glycerol). The majority of the produced fatty acids were composed of C16 and C18 fatty acids. The two most abundant fatty acids in all the cultures were linolenic and palmitic acids. The values of biodiesel properties of oil obtained from S. dimorphus are within the American (ASTM D6751) and European (EN 14214) biodiesel specifications. The results show that S. dimorphus has good potentials for biodiesel oil production and that the productivity can be enhanced by mixotrophic cultivation.

Towards Lipid from Microalgae: Products, Biosynthesis, and Genetic Engineering.

Microalgae can convert carbon dioxide into organic matter through photosynthesis. Thus, they are considered as an environment-friendly and efficient cell chassis for biologically active metabolites. Microalgal lipids are a class of organic compounds that can be used as raw materials for food, feed, cosmetics, healthcare products, bioenergy, etc., with tremendous potential for commercialization. In this review, we summarized the commercial lipid products from eukaryotic microalgae, and updated the mechanisms of lipid synthesis in microalgae. Moreover, we reviewed the enhancement of lipids, triglycerides, polyunsaturated fatty acids, pigments, and terpenes in microalgae via environmental induction and/or metabolic engineering in the past five years. Collectively, we provided a comprehensive overview of the products, biosynthesis, induced strategies and genetic engineering in microalgal lipids. Meanwhile, the outlook has been presented for the development of microalgal lipids industries, emphasizing the significance of the accurate analysis of lipid bioactivity, as well as the high-throughput screening of microalgae with specific lipids.

Sequential co-processing of olive mill wastewater and organic residues by anaerobic co-digestion and pyrolysis for the generation of bioadsorbent and low-cost media for microalgae cultivation

This investigation aims to evaluate the co-valorization of olive mill wastewater with other organic residues involving acid pretreatment, co-digestion, pyrolysis, and microalgae cultivation. Phosphoric acid pretreatment (5%, 60°C for 1 h) was used to solubilize the organic matter in a mixture of coffee grounds, orange peel, olive mill wastewater, and cardboard. The acidic treatment led to the production of 328 Nml of biogas/gVS, while the untreated mixture provided 257 Nml of biogas/gVS. The solid digestates were subjected to pyrolysis (500°C for 1 h), providing a biochar yield of approximately 44% for both digestates. Adsorption tests using methylene blue revealed an adsorption capacity of the biochar generated from the digestate of the acid pre-treated mixture of 4 mg/g, which was higher than that of the biochar from the untreated mixture (3.5 mg/g). The liquid digestates were also used as growth media for microalgae. Compared to the reference media (BG11), the use of the digestates-based media resulted in a lower growth rate (0.04 d-1) and biomass (247 mg/L) but significantly higher lipid content (49%). The study shows, therefore, that the use of acid pretreatment had a positive effect on biogas production (solubilization of sugars), on the adsorption efficiency of the biochar (improvement of the porosity of the material), and on the production of lipids from the microalgae which can be destined to biodiesel.

Identifying Residues for Substrate Recognition in Human GPAT4 by Molecular Dynamics Simulations.

Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the first step in triacylglycerol synthesis. Understanding its substrate recognition mechanism may help to design drugs to regulate the production of glycerol lipids in cells. In this work, we investigate how the native substrate, glycerol-3-phosphate (G3P), and palmitoyl-coenzyme A (CoA) bind to the human GPAT isoform GPAT4 via molecular dynamics simulations (MD). As no experimentally resolved GPAT4 structure is available, the AlphaFold model is employed to construct the GPAT4-substrate complex model. Using another isoform, GPAT1, we demonstrate that once the ligand binding is properly addressed, the AlphaFold complex model can deliver similar results to the experimentally resolved structure in MD simulations. Following the validated protocol of complex construction, we perform MD simulations using the GPAT4-substrate complex. Our simulations reveal that R427 is an important residue in recognizing G3P via a stable salt bridge, but its motion can bring the ligand to different binding hotspots on GPAT4. Such high flexibility can be attributed to the flexible region that exists only on GPAT4 and not on GPAT1. Our study reveals the substrate recognition mechanism of GPAT4 and hence paves the way towards designing GPAT4 inhibitors.

Changes in lipid metabolism track with the progression of neurofibrillary pathology in tauopathies

BackgroundAccumulation of tau leads to neuroinflammation and neuronal cell death in tauopathies, including Alzheimer’s disease. As the disease progresses, there is a decline in brain energy metabolism. However, the role of tau protein in regulating lipid metabolism remains less characterized and poorly understood.MethodsWe used a transgenic rat model for tauopathy to reveal metabolic alterations induced by neurofibrillary pathology. Transgenic rats express a tau fragment truncated at the N- and C-terminals. For phenotypic profiling, we performed targeted metabolomic and lipidomic analysis of brain tissue, CSF, and plasma, based on the LC-MS platform. To monitor disease progression, we employed samples from transgenic and control rats aged 4, 6, 8, 10, 12, and 14 months. To study neuron-glia interplay in lipidome changes induced by pathological tau we used well well-established multicomponent cell model system. Univariate and multivariate statistical approaches were used for data evaluation.ResultsWe showed that tau has an important role in the deregulation of lipid metabolism. In the lipidomic study, pathological tau was associated with higher production of lipids participating in protein fibrillization, membrane reorganization, and inflammation. Interestingly, significant changes have been found in the early stages of tauopathy before the formation of high-molecular-weight tau aggregates and neurofibrillary pathology. Increased secretion of pathological tau protein in vivo and in vitro induced upregulated production of phospholipids and sphingolipids and accumulation of lipid droplets in microglia. We also found that this process depended on the amount of extracellular tau. During the later stages of tauopathy, we found a connection between the transition of tau into an insoluble fraction and changes in brain metabolism.ConclusionOur results revealed that lipid metabolism is significantly affected during different stages of tau pathology. Thus, our results demonstrate that the dysregulation of lipid composition by pathological tau disrupts the microenvironment, further contributing to the propagation of pathology.

Exploring microalgal nutrient-light synergy to enhance CO2 utilization and lipid productivity in sustainable long-term water recycling cultivation

In this work the effects of nutrient availability and light conditions on CO2 utilization and lipid production in Micractinium pusillum KMC8 is reported. The study investigated the ideal nitrogen concentrations for growth and nitrogen utilization in a 15% CO2 environment. Logistic and Gompertz models were employed to analyze the kinetics of KMC8 cell growth. Compared to 17.6 mmol L−1 control nitrogen, which generated 1.6 g L−1 growth, doubling and quadrupling nitrogen concentrations boosted biomass growth by 12.5% and 28.78%. At 8.6 mmol L−1 nitrogen, the growth decreased but lipid productivity increased to 18.62 mg L−1 day−1. At 70.6 mmol L−1 nitrogen, elevated nitrogen levels maintained an alkaline pH above 7 and enhanced CO2 mitigation, achieving 2.27% CO2 utilization efficiency. Nitrogen shows a positive correlation with higher rates of carbon and nitrogen fixation. The investigation extends to find out the influence of phosphorus and light conditions on microalgae. Increasing light intensity incrementally from 150 to 1200 μmol m−2 s−1 with more phosphorus increased biomass productivity by 85% (255 mg L-1 day−1) and lipid productivity by 2.5-fold (84.76 mg L-1 day−1), with 3.3% CO2 utilization efficiency compared to directly using 1200 μmol m−2 s−1. This study suggests a water recycling-fed batch cycle with gradual light feeding, which results in high CO2 fixation (1.1 g L−1 day−1), 7% CO2 utilization, and significant biomass and lipid productivity (577.23 and 150 mg L−1 day−1). This approach promotes lipid synthesis, maintains carbon fixation, and minimizes biomass loss, thus supporting sustainable bioenergy development in a circular bio-economy framework.

Potential use of sludge from El Ferrol Bay (Chimbote, Peru) for the production of lipids in the culture of Scenedesmus acutus (Meyen, 1829)

Despite the extensive development of microalgae biotechnology, it still requires new methodologies to lower production costs, especially in the field of biofuel production. Therefore, innovative methods that facilitate operations and enable cost-effective production are important in driving this industry. In this study, we propose a new low-cost and easy-to-use procedure, addressed to the generation of a culture medium for Scenedesmus acutus. The medium was obtained by thermal reduction of a sludge sample from El Ferrol Bay (Chimbote, Peru), whereby we obtained an aqueous medium. Our results indicated that the aqueous medium incorporates all necessary nutrients for microalgae production; allowing a maximum biomass of 0.75 ± 0.07 g/L with 60% of the medium; while high lipids production (59.42 ± 6.16%) was achieved with 20%. Besides, we quantified, in the experimental medium and at the end of the cultures, the levels of inorganic nutrients such as ammonium, nitrites, nitrates, and phosphates; in addition to COD and TOC, which were significantly reduced (p<\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p<$$\\end{document} 0.05) after 7 days of culture, mainly in the treatment with 20%. These results suggest tremendous potential for sludge reuse, which also entails a cost reduction in microalgae biomass production, with additional positive impacts on large-scale application over highly polluted environments.

Oxidative modification products of lipids in the intraocular fluid of patients with cataracts associated with chronic non-infectious diseases

Introduction. To clarify the role of oxidative stress in the development of cataracts, it is necessary to determine the content of oxidative modification products directly in the eye tissue, but such studies are scarce, which is due to the difficulty of obtaining a sufficient amount of biomaterial for analysis and the need to use highly sensitive research methods as a result. Therefore, to assess the pathological changes in the lens, intraocular or tear fluid is used.Aim. To elucidate the role of oxidative stress in the development of cataracts by determining the content of lipid oxidation products and their comparative characteristics in intraocular fluid and in blood plasma in patients with cataracts associated with chronic non-infectious diseases.Materials and methods. The study involved 83 patients with cataracts associated with non-infectious diseases, who underwent surgical treatment. Of these, 30 patients had chronic obstructive pulmonary disease (COPD) as a comorbid condition, 45 had cardiovascular diseases (CVD), and 13 had diabetes mellitus (DM). The control group consisted of 30 practically healthy individuals without clinical signs of acute or chronic diseases. Lipid oxidation products were determined by ultraviolet spectroscopy. Absorption spectra of non-oxidized lipids (E204), diene conjugates (E233), conjugated trienes, and ketodiene (E278) were recorded. Additionally, the ratios of absorption spectra of diene conjugates to non-oxidized lipids (E233/E204), as well as conjugated dienes and ketodienes to non-oxidized lipids (E278/E204), were calculated. Tear and intraocular fluids, as well as blood plasma, served as materials for the study.Results. In the group of patients with cataracts associated with non-infectious diseases, the content of diene conjugates, conjugated trienes, and ketodienes was increased relative to similar indicators in the tear fluid of people in the control group. Moreover, more pronounced changes were observed in the group of patients with cataracts associated with COPD relative to those with CVD and DM. A comparative analysis confirmed that in the group of patients with cataracts associated with COPD, the content of oxidized lipids in intraocular fluid and in blood plasma was increased. Correlation-regression analysis showed a positive relationship between the indicators of diene conjugates in intraocular fluid and in blood plasma.Conclusions. The significant direct linear relationship between the indicators of oxidized lipids in intraocular fluid and in blood plasma in patients with cataracts and non-infectious diseases may indicate the possibility of using blood plasma for studying oxidative processes in the lens and its pathological changes for the purpose of selecting therapy and evaluating treatment efficacy. The results obtained confirm the role of oxidative stress in the development of cataracts in patients with chronic non-infectious diseases.

Production of docosahexaenoic acid by a novel isolated Aurantiochytrium sp. 6-2 using fermented defatted soybean as a nitrogen source for sustainable fish feed development.

We focused on the production of docosahexaenoic acid (DHA)-containing microbial lipids by Aurantiochytrium sp. using of defatted soybean (DS) as a nitrogen source. Defatted soybean is a plant biomass that could provide a sustainable supply at a low cost. Results showed that Aurantiochytrium sp. could not directly assimilate the DS as a nitrogen source but could grow well in a medium containing DS fermented with rice malt. When cultivated in a fermented DS (FDS) medium, Aurantiochytrium sp. showed vigorous growth with the addition of sufficient sulfate and chloride ions as inorganic nutrients without seawater salt. A novel isolated Aurantiochytrium sp. 6-2 showed 15.8±3.4g/L DHA productivity (in 54.8±12.1g/L total fatty acid production) in 1L of the FDS medium. Therefore, DHA produced by Aurantiochytrium sp. using FDS enables a stable and sustainable DHA supply and could be an alternative source of natural DHA derived from fish oil.

Abstract 396: Effects of hypoxia on cell proliferation and lipidome profile in treatment-resistant prostate cancer cells

Abstract Background: Low tissue content of oxygen i.e. hypoxia is typical in prostate cancer (PCa) tumor microenvironment. Hypoxia is also associated with PCa progression and treatment resistance. Modulation of lipid and cholesterol metabolism seems to be one way how tumor cells adapt to hypoxia. However, not much is known about lipidomic profiles in hypoxic condition in advanced PCa and treatment resistance. Aim: The aim of this study was to evaluate the impact of hypoxia on treatment-resistant PCa cells and investigate alterations in the lipidome under hypoxic conditions. Material and Methods: Testosterone (T)-sensitive, T-independent (castration-resistant), and enzalutamide (enza)-resistant VCaP PCa cells were cultured for three days under hypoxia (1% O2) and compared with cells grown under normoxia (21% O2). Additionally, cells were treated with the drugs SREBP-inhibitor fatostatin and mevalonate-pathway inhibitor simvastatin to examine the effects of modulating lipid and cholesterol production on hypoxia responses. Relative cell growth by crystal violet staining and live/dead cell ratio were evaluated after each treatment. Intracellular lipidome was measured using liquid chromatography coupled with MS/MS method. Random forest classification was used of the selection of the lipids. Based on the classification, concentration differences between the groups were calculated. Results: Growth of the T-sensitive and castration-resistant cells was decreased under hypoxia compared to normoxia. However, enza-resistant cells tolerated hypoxic conditions. Lipid-modifying drugs exhibited similar inhibitory effects on cell growth in both normoxia and hypoxia. Based on live/dead cell ratio, hypoxia induced cell death. Lipidome profiles varied markedly by oxygen content and cellular treatment resistance profile. Simvastatin treatment also influenced lipidome profiles. Conclusions: Enza-resistant advanced PCa cells tolerated hypoxic conditions better compared to T-sensitive and T-independent cells. Lipidome was different between cell lines but also in hypoxia compared to normoxia, supporting its importance for PCa cells under varying conditions. Interference with lipid metabolism leads to growth inhibition regardless of hypoxia. These findings could be used in identifying potential markers for predicting or delaying disease progression in advanced PCa. Future studies should explore the efficacy of various lipidome-modulating drugs in delaying disease progression in PCa. Citation Format: Aino Siltari, Kalle Välitalo, Tomas Laamanen, Kaisa Tornberg, Alvar Saarinen, Joose Kreuzer, Heimo Syvälä, Teuvo L. Tammela, Pauliina Ilmonen, Pasi Kallio, Teemu J. Murtola. Effects of hypoxia on cell proliferation and lipidome profile in treatment-resistant prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 396.

Abstract 4451: Regulation of lipid metabolism and ferroptosis by DAXX

Abstract Intracellular lipid production in cancer cells supplies lipids to synthesize cell membranes and signaling molecules during rapid cell proliferation and tumor growth. Cancer cells also utilize fatty acid oxidation (FAO) to generate ATP to meet their energy demand. Notably, lipid metabolites can inhibit and trigger ferroptosis due to iron-dependent oxidation of polyunsaturated fatty acids (PUFAs). Therefore, identifying regulators that maintain the intricate balance of lipid biosynthesis required for cell proliferation and survival is critical in cancer biology and therapy. Lipid metabolism is regulated by two oncogenic signaling pathways: the RAS-RAF-MEK-MAPK and the mammalian target of rapamycin (mTOR) pathways. About 30% of all cancers harbor constitutively active mutations in KRAS, HRAS, or NRAS, resulting in hyperactive RAS-RAF-MEK-MAPK signaling to drive tumorigenesis, metastatic progression, immune evasion, and resistance to therapy. KRAS regulates lipid uptake, lipid synthesis, and FAO. mTOR is a serine/threonine kinase acting as a key intracellular signaling hub to regulate nutrient homeostasis, metabolism, protein synthesis, and autophagy. The mTORC1 complex promotes lipogenesis. The RAS and mTOR signaling pathways exhibit both positive and negative cross-regulation. The coordinated activity of both pathways is critical to sustained tumor growth. Notably, mTORC1 signaling inhibition enhances RAS-RAF-MEK-MAPK signaling to promote cancer cell survival and proliferation. Furthermore, constitutive mTORC1 signaling induces cell death when the supply of unsaturated FAs is limited. However, the molecular link for coordinating the activity of the RAS and mTOR signaling pathways remains poorly defined. Death domain-associated protein (DAXX) is essential for mouse embryonic development and has ill-defined pro-cell survival functions. Our lab has a long-standing interest in deciphering DAXX’s complex biological functions. Our recent study shows that DAXX drives tumorigenesis by promoting lipogenic gene expression and lipid synthesis through interacting with sterol regulatory element-binding proteins SREBP1 and SREBP2 (SREBP1/2) (Mahmud et al., 2023, PMID 37045819). Unexpectedly, our new data reveal that DAXX inhibits ferroptosis. Significantly, phosphorylation via RAS signaling appears to regulate DAXX’s activity in lipid synthesis and resistance to ferroptosis. Remarkably, disruption of DAXX-mediated lipid synthesis potentiates ferroptosis due to mTORC1 activity. Based on these observations, we propose that stimulated by the RAS-RAF-MEK-MAPK oncogenic signaling, DAXX promotes tumorigenesis through upregulating genes for lipid synthesis and resistance to ferroptosis, and that the lack of DAXX-mediated lipid synthesis leads to sensitization of cells to ferroptosis due to mTORC1’s proliferative effects. (Supported by FDOH grant 23K03). Citation Format: Wenlin Yang, Nikee Awasthee, Qi Chen, Seth Hale, Daiqing Liao. Regulation of lipid metabolism and ferroptosis by DAXX [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4451.