High Lipid Accumulation Research Articles

Mycelial mass, microbial lipids and γ-linolenic acid (GLA) by Cunninghamella elegans cultivated on agro-industrial residues

In the current study, the Zygomycetes fungus Cunninghamella elegans NRRL Y-1392 was evaluated for its ability to grow in extracts derived from dried and ground agricultural residues, such as mushroom stalks and roots from hydroponically cultivated lettuces and produce poly-unsaturated fatty acids (PUFA) and γ-linolenic acid (GLA) rich lipids. Initially, the compositions of stalks and lettuce roots were analysed, and the fungus was batch-flask cultivated on six different commercial semi-defined substrates containing different sugars detected in stalks and roots to evaluate its catabolic ability. C. elegans was capable to assimilate all sugars, but at a lower rate in the case of arabinose. Subsequently, C. elegans was cultivated on tailor-made semi-defined commercial substrates, resembling hydrolysates containing carbohydrates found in mushroom stalks, under both nitrogen-excess and nitrogen-limited conditions, and resembling that of hydrolysates of roots, under nitrogen-excess conditions. Based on the results, under nitrogen-excess conditions, in the case of media resembling stalks hydrolysates, higher production values for biomass, PUFAs, and GLA were observed (20.3 g/L, 1906 mg/L, 668 mg/L), accompanied by high productivity values due to short cultivation periods, while under nitrogen limitation, high lipid accumulation (lipid in dry cell weight =48%, w/w) was presented, and lipids rich in oleic acid were produced. Finally, the fungus was cultivated on a medium derived from hot water-extraction applied to mushroom stalks, enriched with organic nitrogen sources. The fungus was successfully grown on the sugar-rich water-extract derived from mushroom stalks, resulting in dry biomass of 14.5 g/L, lipids of 1.8 g/L, with 15% (w/w) of GLA in cellular lipids.

Increase in polyunsaturated fatty acids and carotenoid accumulation in the microalga Golenkinia brevispicula (Chlorophyceae) by manipulating spectral irradiance and salinity.

Microalgal biotechnology offers a promising platform for the sustainable production of diverse renewable bioactive compounds. The key distinction from other microbial bioprocesses lies in the critical role that light plays in cultures, as it serves as a source of environmental information to control metabolic processes. Therefore, we can use these criteria to design a bioprocess that aims to stimulate the accumulation of target molecules by controlling light exposure. We study the effect on biochemical and photobiological responses of Golenkinia brevispicula FAUBA-3 to the exposition of different spectral irradiances (specifically, high-fluence PAR of narrow yellow spectrum complemented with low intensity of monochromatic radiations of red, blue, and UV-A) under prestress and salinity stress conditions. High light (HL) intensity coupled to salinity stress affected the photosynthetic activity and photoprotection mechanisms as shown by maximal quantum yield (Fv/Fm) and non-photochemical quenching (NPQmax) reduction, respectively. HL treatments combined with the proper dose of UV-A radiation under salinity stress induced the highest carotenoid content (2.75 mg g dry weight [DW]- 1) composed mainly of lutein and β-carotene, and the highest lipid accumulation (35.3% DW) with the highest polyunsaturated fatty acid content (alpha-linolenic acid (C18:3) and linoleic acid (C18:2)). Our study can guide the strategies for commercial indoor production of G. brevispicula for high-value metabolites.

Responses of Dunaliella sp. AL-1 to chromium and copper: Biochemical and physiological studies

Microalgae have gained recognition as versatile candidates for the remediation of heavy metals (HMs). This study investigated the biosorption potential of Dunaliella sp. AL1 for copper (Cu(II)) and hexavalent chromium (Cr(VI)) in aqueous solutions. The marine microalga Dunaliella sp. AL1 was exposed to half-sublethal concentrations of both metals in single and bimetallic systems, and responses in algal growth, oxidative stress, photosynthetic pigment production, and photosynthetic performance were evaluated. Cu and/or Cr exposure increased the generation of reactive oxygen species (ROS) in microalgae cells but did not impact algal growth. In terms of photosynthesis, there was a decrease in chlorophylls and carotenoids production in the microalgae culture treated with Cr, either alone or in combination with Cu. The study recorded promising metal removal efficiencies: 26.67%–20.11% for Cu and 94.99%–95.51% for Cr, in single and bimetallic systems, respectively. FTIR analysis revealed an affinity of Cu and Cr ions towards aliphatic/aldehyde C–H, N–H bending, and phosphate groups, suggesting the formation of complex bonds. Biochemical analysis of microalgae biomass collected after the removal of Cr alone or in combination with Cu showed a significant decrease in total carbohydrate content and soluble protein levels. Meanwhile, higher lipid accumulation was recorded and evidenced by BODIPY 505/515 staining. Fatty acid composition analysis by GC revealed a modulation in lipid composition, with a decrease in the ratio of unsaturated fatty acids (UFA) to saturated fatty acids (SFA), in response to Cu, Cr, and Cu–Cr exposure, indicating the suitability of the biomass for sustainable biofuel production.

Regulation of AreA on lipid biosynthesis under different nitrogen sources and C/N ratios in the model oleaginous fungus Mucor circinelloides

Mucor circinelloides has been exploited as model filamentous fungi for studies of genetic manipulation of lipogenesis. It is widely recognized that lipid accumulation is increased when there is a lack of nitrogen source in oleaginous microorganism. Nitrogen metabolism in filamentous fungi is a complex process that can be regulated by the global nitrogen regulator AreA. In this study, we cultivated the areA-knockout and -overexpression strains obtained in our previous study, using 20 different nitrogen sources. It emerged that the disruption of AreA in M. circinelloides reduced its sensitivity to nitrogen availability, resulting in increased lipid synthesis. Specially, the areA-knockout strain was unable to fully utilize many nitrogen sources but the ammonium and glutamate. We continued to investigate lipid production at different molar C/N ratios using glucose as sole carbon source and ammonium sulfate as sole nitrogen source, of which the high C/N ratios activate high lipid accumulation. By comparing the experimental results with transcriptional analysis, we were able to identify the optimal process conditions suitable for lipid accumulation and potential targets for future metabolic engineering.

Microalgae Isolated from Singapore Mangrove Habitat as Promising Microorganisms for the Sustainable Production of Omega-3 Docosahexaenoic Acid

Docosahexaenoic acid (DHA, C22:6n-3) is an omega-3 fatty acid with beneficial effects for human health. In view of its increasing demand, DHA traditionally produced by marine fisheries will be insufficient, and an alternative sustainable source is urgently required. Here, we report the isolation and characterization of four novel microalgae strains, PLU-A, B, C and D, with a high DHA content of up to 45% from decayed mangrove samples collected from a coastal area in Singapore. Phylogenetic analysis revealed that these isolates were clustered with Schizochytrium sp. TK6 (OK244290.1) and were identified as Schizochytrium sp. strains. A medium optimization with Schizochytrium sp. PLU-D found a glucose-to-yeast extract ratio of 4:1 to be optimal for high biomass and lipid accumulation of up to 70% in shake flasks. In fed-batch fermentation scale-up with the Schizochytrium sp. PLU-D strain, this translates to 175 g/L dry biomass, 94 g/L lipid and 36.2 g/L DHA. Accordingly, the DHA titer obtained is superior to most of the scale-up production reported thus far, while the DHA content is comparable to two other commercially available DHA algae oils. These results suggest that Schizochytrium sp. PLU-D has high potential to be applied for the sustainable production of DHA.

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.

High-throughput screening of non-conventional yeasts for conversion of organic waste to microbial oils via carboxylate platform

Converting waste into high-value products promotes sustainability by reducing waste and creating new revenue streams. This study investigates the potential of diverse yeasts for microbial oil production by utilizing short-chain fatty acids (SCFAs) that can be produced from organic waste and focuses on identifying strains with the best SCFA utilisation, tolerance and lipid production. A collection of 1434 yeast strains was cultivated with SCFAs as the sole carbon source. Eleven strains emerged as candidates with promising growth rates and high lipid accumulation. Subsequent fermentation experiments in liquid SCFA-rich media, which focused on optimizing lipid accumulation by adjusting the carbon to nitrogen (C/N) ratio, showed an increase in lipid content at a C/N ratio of 200:1, but with a concurrent reduction in biomass. Two strains were characterized by their superior ability to produce lipids compared to the reference strain Yarrowia lipolytica CECT124: Y. lipolytica EXF-17398 and Pichia manshurica EXF-7849. Characterization of these two strains indicated that they exhibit a biotechnologically relevant balance between maximizing lipid yield and maintaining growth at high SCFA concentrations. These results emphasize the potential of using SCFAs as a sustainable feedstock for oleochemical production, offering a dual benefit of waste valorisation and microbial oil production.

Diosgenin intervention: targeting lipophagy to counter high glucose diet-induced lipid accumulation and lifespan reduction.

The online version contains supplementary material available at 10.1007/s13205-024-04017-3.

Mitochondrial players as novel therapeutic options in arrhythmogenic cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Joint Project Südtirol- FWF (grant number 23623; Italy-Austria) and the Department of Innovation, Research and University of the Autonomous Province of Bolzano-South Tyrol (Italy) Background Mitochondria are dynamic organelles that sense and respond to environmental, nutritional, and pathological changes. These organelles can smartly adapt to different stressful conditions, by changing the way they network or the energy sources they use. Over the past years, numerous disorders have been associated with mitochondrial dysfunction, including cardiomyopathies. Arrhythmogenic Cardiomyopathy (ACM) is a cardiac disease characterized by the progressive replacement of the myocardium with fibro-fatty tissue. The current treatment primarily focuses on managing the symptoms rather than addressing the underlying issue of tissue substitution. Purpose: Therefore, in this study, we explored the mitochondrial and metabolic phenotype in ACM and tested the efficacy of a mitochondria-targeting library to rescue the fibro-fatty phenotype in ACM Methods: Human primary cardiac stromal cells (CStCs) were cultured in adipogenic medium (AM), a condition used to model the ACM fibro-fatty phenotype. Mitochondria-related analyses of ultrastructure, membrane potential, network connection, respiratory capacity, ROS production and redox system were performed at day (d) d0, d3, d7, d15 of AM exposure. A mitochondria-targeting library (MedChem Express) was tested on ACM-CStCs exposed to AM for 7 days. The extent of lipid accumulation was determined using the neutral lipid staining dye BODIPY 493/503, cell numbers were measured using Hoechst counterstaining, and images acquired using a high-content imaging system Results: At d0, the mitochondrial network was more fragmented in ACM compared to healthy CStCs (CTR). This result was in line with the observation of a decrease in mitochondrial respiratory capacity and an increase in ROS production. In addition, AM exposure led to faster and higher lipid accumulation in ACM CStCs, which was associated with higher mitochondrial oxygen consumption rates observed in ACM CStCs after 7 days of AM exposure. When ACM CStCs were simultaneously exposed to AM and 407 mitochondrial-directed compounds, about 25% of the compounds demonstrated the ability to reduce lipid accumulation Conclusion: ACM CStCs demonstrate an increased risk for mitochondrial network impairment. Moreover, prolonged exposure of ACM CStCs cells to AM negatively affects lipid deposition as well as mitochondrial and metabolic parameters. This highlights the potential for using specific mitochondria-targeting compounds to reduce lipid accumulation.

β-sitosterol alleviates high fatty acid-induced lipid accumulation in calf hepatocytes by regulating cholesterol metabolism

A significant reduction in plasma concentration of cholesterol during early lactation is a common occurrence in high-yielding dairy cows. An insufficient synthesis of cholesterol in the liver has been linked to lipid accumulation caused by high concentrations of fatty acids during negative energy balance (NEB). As ruminant diets do not provide quantitative amounts of cholesterol for absorption, phytosterols such as β-sitosterol may serve to mitigate the shortfall in cholesterol within the liver during NEB. To gain mechanistic insights, primary hepatocytes were isolated from healthy female 1-day old calves for in vitro studies with or without 1.2 mM fatty acids (FA) to induce metabolic stress. Furthermore, hepatocytes were treated with 50 μM β-sitosterol with or without FA. Data were analyzed by one-way ANOVA with subsequent Bonferroni correction. Results revealed that calf hepatocytes treated with FA had greater content of non-esterified fatty acids (NEFA) and triacylglycerol (TAG), and greater mRNA and protein abundance of the lipid synthesis-related SREBF1 and FASN. In contrast, mRNA and protein of CPT1A (fatty acid oxidation) and the cholesterol metabolism-related targets SREBF2, HMGCR, ACAT2, APOA1, ABCA1 and ABCG5 was lower. Content of the antioxidant-related glutathione (GSH) and activities of superoxide dismutase (SOD) also was lower. Compared with FA challenge alone, 50 μM β-sitosterol led to greater mRNA and protein abundance of SREBF2, HMGCR, ACAT2 and ABCG5, and greater content of GSH and activity of SOD. In contrast, compared with the FA group, the mRNA and protein abundance of SREBF1 and ACC1 and the content of TAG and NEFA in the β-sitosterol + FA group were lower. Overall, β-sitosterol can promote cholesterol metabolism and reduce oxidative stress while reducing lipid accumulation in hepatocytes challenged with high concentrations of fatty acids.

Regulation of Myocardial Lipid Accumulation in the Development of Obesity

Energy metabolism is important in the development of heart disease, which is the leading cause of death worldwide. The importance of energy metabolism in disease is becoming even more clear with the rise in obesity, metabolic diseases, and the recognition that they all fit together as with the recent offcial report of a new syndrome named Cardiovascular-Kidney-Metabolic (CKM) Syndrome. A complete understanding of myocardial lipid storage and subsequent utilization of lipids is essential to understanding the impact of these metabolic diseases in the heart and on the development of cardiac dysfunction and hypertrophy. In this study we investigate how the heart controls fuel storage by taking advantage of the impact of the transcription factor peroxisome proliferator activated receptor α (PPARα) on 1) fatty acid metabolism and lipid accumulation, 2) its key role in sex differences in cardiac hypertrophy which we previously reported, and 3) the regulation of lipid droplets. It is controversial whether a decline in myocardial PPARα mediates cardiac hypertrophy and whether it increases or reduces lipid accumulation. Using our tamoxifen inducible cardiac-specific PPARα knockout mouse (cPPAR−/−) we see less cardiac lipid accumulation in response to a 5 week high fat diet. Our data indicate that this difference in triglyceride levels is present in both males and females. Importantly, this is not driven by a difference in fatty acid supply to these hearts. Serum fatty acid levels are not lower in cPPAR−/− vs Control mice fed a high fat diet. Further, we have not observed a difference in high fat diet induced body weight gain between cPPAR−/− and Control mice. We have begun to examine how these differences in high fat diet-induced lipid accumulation correlate with cardiac hypertrophy by looking at heart weight normalized to tibia length. While we did not expect 5 weeks of a high fat diet to induce cardiac hypertrophy, it is possible that the difference in cardiac lipid storage in the cPPAR−/− hearts could impact this. This measurement did not indicate a difference in cardiac hypertrophy between high fat diet fed cPPAR−/− and Control mice. We are utilizing this mouse as a model to investigate the regulation of lipid droplets and the lipid droplet proteome. So far, our results are indicating that the regulation of lipid droplet proteins is not affected in a uniform manner. For example, our data is suggesting that the expression of different members of the perilipin family are affected in distinct ways. Overall, these data indicate that a reduction in cardiac PPARα protects against obesity induced cardiac lipid accumulation. Going forward, it will be interesting to see how these changes occur in relation to the lipid droplet proteome and whether any changes that occur differentially in males vs female may be involved in sex differences in cardiac hypertrophy. Better understanding these factors will be essential for the development of safe and effective future therapies for CKM syndrome and other cardiovascular diseases. ND-EPSCoR. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Valorization of Sugarcane Vinasse and Crude Glycerol for Single-Cell Oils Production by Rhodotorula glutinis R4: A Preliminary Approach to the Integration of Biofuels Industries for Sustainable Biodiesel Feedstock

Single-cell oils (SCOs) offer a promising alternative to conventional biodiesel feedstocks. The main objective of this work was to obtain SCOs suitable for biodiesel production from the oleaginous yeast Rhodotorula glutinis R4 using sugarcane vinasse from a local sugar-derived alcohol industry as the substrate. Additionally, crude glycerol from the local biodiesel industry was evaluated as a low-cost carbon source to replace expensive glucose and as a strategy for integrating the bioethanol and biodiesel industries for the valorization of both agro-industrial wastes. R4 achieved a high lipid accumulation of 88% and 60% (w/w) in vinasse-based culture media, containing 10% and 25% vinasse with glucose (40 g L−1), respectively. When glucose was replaced with crude glycerol, R4 showed remarkable lipid accumulation (40%) and growth (12.58 g L−1). The fatty acids profile of SCOs showed a prevalence of oleic acid (C18:1), making them suitable for biodiesel synthesis. Biodiesel derived from R4 oils exhibits favorable characteristics, including a high cetane number (CN = 55) and high oxidative stability (OS = 13 h), meeting international biodiesel standards (ASTMD6751 and EN14214) and ensuring its compatibility with diesel engines. R. glutinis R4 produces SCOs from vinasse and crude glycerol, contributing to the circular economy for sustainable biodiesel production.

Histopatologi Hepar Tikus Dengan Induksi Pakan Tinggi Lemak Setelah Pemberian Biji Mahoni

High accumulation of lipids in hepatocytes can trigger an increase in the production of radical compounds, leading to fatty liver disease. This condition induces histological changes in the liver, especially in hepatocytes, and affects the surrounding structures. Mahogany seeds have the potential to act as a hypolipidemic agent in treating fatty liver. Mahogany seeds are known to contain phytochemical compounds which act as antioxidants. This study aimed to determine liver histopathology of rats by inducing high-fat diet after giving mahogany seeds ethanol extract which was observed through the percentage of steatosis, hepatocyte diameter, and hepatosomatic index. This study involved thirty male Sprague Dawley rats, divided into 6 groups: P0 (given commercial feed), P1 (given high-fat diet), P2 (given high-fat diet and simvastatin at a dose of 8 mg/200 g BW), P3, P4, and P5 (given high-fat diet and mahogany seeds ethanol extract at a dose of 14, 28, and 56 mg/200 g BW). The results showed that the hepatosomatic index among all treatment groups did not differ significantly; however, the percentage of steatosis and hepatocyte diameter in the groups given mahogany seeds ethanol extract significantly differed from the group given only high-fat feed. Based on these results, it can be concluded that mahogany seed ethanol extract can maintain the histological structure of the liver in male Sprague Dawley rats with fatty liver. Keywords: hepatocyte, hepatosomatic index, high-fat diet, mahogany seeds, steatosis

Lipid metabolism and MAPK-ICE1 cascade play crucial roles in cold tolerance of banana

Low temperature is a major environmental factor that limits the growth, yield, and geographical distribution of Cavendish and Dajiao bananas (Musa spp.). Dajiao bananas exhibit a significantly higher cold tolerance than the Cavendish cultivar. However, the underlying mechanisms involved in cold tolerance regulation in Dajiao plants have not been determined. In this study, we investigated the mechanisms underlying the differences in cold tolerance at the cellular level between the cold-sensitive Cavendish and cold-tolerant Dajiao banana types through comparative metabolomics and transcriptomics analyses in calli exposed to cold treatment under dark conditions. A higher accumulation of lipids was observed in Dajiao calli cells compared to Cavendish cells under cold stress. After cold treatment, 4,626 and 5,516 differentially expressed genes (DEGs) were identified in Cavendish and Dajiao banana cells, respectively. By integrating the transcriptomic and metabolomic datasets, we discovered that the linoleic acid and α-linoleic acid metabolism and the Abscisic acid (ABA)-independent Mitogen-activated protein kinase (MAPK) cascade-Inducer of CBF expression 1 (ICE1) signal transduction pathway (including Mitogen-activated protein kinase kinase kinase 1 [MEKK1], MAPK5, ICE1, and Cold-regulated 47 [COR47]) played crucial roles in the cold tolerance of Dajiao bananas. Our study provides new insights into cold response regulation and novel cold tolerance mechanisms, providing valuable leads and targets for the genetic improvement of cold tolerance in bananas.

κ-Carrageenan/konjac glucomannan composite hydrogel-based 3D porcine cultured meat production

Alternative technology for cultured meat production holds the potential to alleviate ethical, environmental, and public health concerns stemming from conventional husbandry. As a key food component, fat plays a crucial role in the sensory characteristics and nutritional value of meat products. However, current adipose tissue engineering protocols have so far proven unsuitable for edible cultured fat production. In this study, hybrid hydrogels based on Κ-Carrageenan (Car) and konjac glucomannan (KGM) were designed as a culture scaffold for adipocytes. The edible hydrogel with excellent biocompatibility, food safety, and low cost was demonstrated to support cell proliferation and allow the formation of tissue-like cell spheres. Furthermore, both porcine subcutaneous pre-adipocytes (PreAs) and fibro-adipogenic progenitors (FAPs) acquired mature adipocyte characteristics and higher lipid accumulation in Car-KGM (CK) hydrogel, suggesting its superior ability to support in vitro adipogenesis than conventional monolayer culture and alginate (Alg)-based 3D culture. Taken together, the excellent nature of CK hydrogel makes it a versatile platform for improving the molecular and cellular phenotypes of a variety of adipocyte models. The established spheroid model opens possibilities for broad applications in cultivated fat and represents a viable strategy for the manufacture of ‘snowflake pork’.

Atherosclerotic plaque development in mice is enhanced by myeloid ZEB1 downregulation

Accumulation of lipid-laden macrophages within the arterial neointima is a critical step in atherosclerotic plaque formation. Here, we show that reduced levels of the cellular plasticity factor ZEB1 in macrophages increase atherosclerotic plaque formation and the chance of cardiovascular events. Compared to control counterparts (Zeb1WT/ApoeKO), male mice with Zeb1 ablation in their myeloid cells (Zeb1∆M/ApoeKO) have larger atherosclerotic plaques and higher lipid accumulation in their macrophages due to delayed lipid traffic and deficient cholesterol efflux. Zeb1∆M/ApoeKO mice display more pronounced systemic metabolic alterations than Zeb1WT/ApoeKO mice, with higher serum levels of low-density lipoproteins and inflammatory cytokines and larger ectopic fat deposits. Higher lipid accumulation in Zeb1∆M macrophages is reverted by the exogenous expression of Zeb1 through macrophage-targeted nanoparticles. In vivo administration of these nanoparticles reduces atherosclerotic plaque formation in Zeb1∆M/ApoeKO mice. Finally, low ZEB1 expression in human endarterectomies is associated with plaque rupture and cardiovascular events. These results set ZEB1 in macrophages as a potential target in the treatment of atherosclerosis.

Selecting for a high lipid accumulating microalgae culture by dual growth limitation in a continuous bioreactor

A dual-growth-limited continuous operated bioreactor (chemostat) was used to enhance lipid accumulation in an enrichment culture of microalgae. The light intensity and nitrogen concentration where both limiting factors resulting in high lipid accumulation in the mixed culture. Both conditions of light and nitrogen excess and deficiency were tested. Strategies to selectively enrich for a phototrophic lipid-storing community, based on the use of different nitrogen sources (ammonium vs. nitrate) and vitamin B supplementation in the growth medium, were evaluated. The dual limitation of both nitrogen and light enhanced the accumulation of storage compounds. Ammoniacal nitrogen was the preferred nitrogen source. Vitamin B supplementation led to a doubling of the lipid productivity. The availability of vitamins played a key role in selecting an efficient lipid-storing community, primarily consisting of Trebouxiophyceae (with an 82 % relative abundance among eukaryotic microorganisms). The obtained lipid volumetric productivity (387 mg L−1 d−1) was among the highest reported in literature for microalgae bioreactors. Lipid production by the microalgae enrichment surpassed the efficiencies reported for continuous microalgae pure cultures, highlighting the benefits of mixed-culture photo-biotechnologies for fuels and food ingredients in the circular economy.

Different Starch Sources Affect the Growth Performance and Hepatic Health Status of Largemouth Bass (Micropterus salmoides) in a High-Temperature Environment.

The experiment was designed to investigate the effects of different starch types on the growth performance and liver health status of largemouth bass in a high-temperature environment (33-35 °C). In this study, we designed five diets using corn starch (CS), tapioca starch (TS), sweet potato starch (SPS), potato starch (PS), and wheat starch (WS) as the starch sources (10%). We selected 225 healthy and uniformly sized largemouth bass (199.6 ± 0.43 g) and conducted the feeding experiment for 45 days. The results showed that the WS group had the highest WGR, SGR, and SR and the lowest FCR. Among the five groups, the WS group had the highest CAT activity, SOD activity, and GSH content, while the SPS group had the highest MDA content. Furthermore, oil red O staining of liver samples showed that the TS group had the largest positive region, indicating high lipid accumulation. Lastly, the gene expression results revealed that compared with the WS group, the CS, TS, and SPS groups showed suppressed expression of nrf2, keap1, cat, sod, gpx, il-8, and il-10. Therefore, our results demonstrated the effect of different starch sources on largemouth bass growth performance and hepatic health in a high-temperature environment.

Metabolic engineering of Schizochytrium sp. for superior docosahexaenoic acid production

Schizochytrium sp. is an industrial producer of docosahexaenoic acid (DHA), which is an important omega-3 polyunsaturated fatty acid used in the nutraceutical and food industry. Here, we rewired the carbon metabolism of Schizochytrium sp. ATCC20888 for superior DHA production and constructed 18 engineered strains through combinatorial gene manipulation of 8 crucial genes (acc, acl, ampD, dga1, mae, mfe1, pex10, and zwf) related to lipogenesis. Reducing β-oxidations (∆pex10, ∆mfe1), reinforcing the biosynthetic precursors supply (OACC, OACL, OAMPD), reinforcing NADPH supply (OMAE, OZWF), or promoting TAG formation (ODGA1) efficiently promoted DHA and lipid production of Schizochytrium. MAE and DGA1 overexpression exhibited cooperativity towards increasing DHA production and lipogenesis in the WT strain and ACC-overexpression strain, but had no cooperative advantage in the ∆pex10 strain. The highest lipid content (82.2%) and DHA yield (7.04 g/L) were obtained in an engineered strain OACL-ACC/∆pex10, which is 72.1% higher than DHA yield of parental strain. Therefore, inhibition of β-oxidations and ample biosynthetic precursors supply are the determining factors for high DHA productivity and lipid accumulation of Schizochytrium.

Gracilaria chorda subcritical water ameliorates hepatic lipid accumulation and regulates glucose homeostasis in a hepatic steatosis cell model and obese C57BL/6J mice

Ethnopharmacological relevanceRed seaweed, known as Rhodophyta, has a long history of use in traditional Asian medicine, including Traditional Chinese Medicine and Ayurveda. It is believed to have cooling and detoxification properties. Red seaweed species, such as Gracilaria, have been used in traditional remedies to address various conditions, such as inflammation, thyroid disorders, and digestive issues. Aim of the studyObesity is a risk factor of hepatic steatosis, a hallmark of non-alcoholic fatty liver disease (NAFLD) that affects nearly 25% of the worldwide population. Gracilaria chorda (GC) contains bioactive peptides that may be applicable in the prevention of metabolic syndrome diseases. This study investigated the effects of GC subcritical water extract at 210 °C (GCSW210) on preventing liver injury and lipid and glucose dysregulation in an oleic acid (OA)-induced hepatic steatosis cell model (HepG2) and high-fat diet (HFD)-induced obese animal model (C57BL/6J mice). Materials and methodsHuman hepatoma HepG2 cells were exposed to 0.1 mM OA for 24 h to induce hepatic steatosis and C57BL/6J mice were fed a HFD for 13 weeks. For lipid accumulation, triglyceride (TG) content was measured in both models, along with free fatty acid (FFA), plasma glucose, and insulin levels in HFD-fed mice. Protein expression of master regulators of adipogenesis and lipogenesis, as well as cholesterol and mitochondrial biosynthesis, was studied via western blotting in hepatic steatosis-induced in vitro and in vivo models. In addition, protein expression of the insulin signaling cascade in skeletal muscle tissues of HFD-fed mice was studied. ResultsGCSW210 significantly decreased lipid accumulation in HepG2 cells exposed to OA and suppressed the expression of lipogenic factors, such as sterol regulatory element-binding protein (SREBP)-1c and fatty acid synthase. In addition, GCSW210 abrogated transcription factors related to cholesterol biosynthesis, such as SREBP-2 and low-density lipoprotein receptor. Similarly, FFA, TG, serum glutamic acid, aspartate transaminase, alanine transferase, plasma glucose, and insulin levels were also significantly reduced in GCSW210-treated HFD-fed mice, which were comparable to the positive control mice treated with Garcinia cambogia extract. Additionally, GCSW210 enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase in the hepatic tissues of HFD-fed mice. Moreover, GCSW210 treatment improved insulin signal transduction by reducing insulin receptor substrate 1 Ser307 phosphorylation and elevated phosphatidylinositol 3-kinase/protein kinase B and glucose transporter type 4 protein expression in muscle tissue. 5-Hdroxymethylfufural (5-HMF) was confirmed to be active substances isolated from GCSW210 through LC-PDA and LC-MS. ConclusionsGCSW210 significantly regulated glucose metabolism, alleviated insulin resistance (IR) induced by high fatty acid synthesis and lipid accumulation, and elevated de novo lipogenesis by activating AMPK phosphorylation in both the liver and muscle tissues of HFD-fed mice. GCSW210 may be a potential functional food for preventing HFD-induced metabolic diseases, such as IR, NAFLD, and type 2 diabetes mellitus.