In this work, a kinetics‐integrated CFD model based on coupling computational fluid dynamics (CFD) and biokinetic was developed to guide the industrial scale‐up for fermentation of docosahexaenoic ...acid (DHA). Two‐substrate biokinetic equations for a 5 L bioreactor with oxygen and nitrogen source as limiting substrates were established, which were further coupled with CFD to simulate the biomass growth and lipid accumulation as well as flow field environment in the fermentation process. The coupled CFD‐biokinetic model can accurately reflect the changes of each relevant variable in the 50 L bioreactor under different operating conditions. The optimal working conditions of a 35 m3 bioreactor were predicted by this model and have secured the one‐step scale‐up of DHA fermentation, resulting in a biomass, lipid concentration, and DHA content in lipids of 99.2 g/L, 55.7 g/L, and 52.5%, respectively. This study thus provides an effective strategy for rapid industrial scale‐up of DHA production.
Schizochytrium sp. is a heterotrophic microorganism capable of accumulating polyunsaturated fatty acids and has achieved industrial production of docosahexaenoic acid (DHA). It also has the potential ...for eicosapentaenoic acid (EPA) production. In this study, it was found that the cell growth, lipid synthesis and fatty acid composition of Schizochytrium sp. were significantly affected by the level of cobalamin in the medium, especially with regard to the content of EPA in the fatty acids. The content of EPA in the fatty acids increased 17.91 times, reaching 12.00%, but cell growth and lipid synthesis were significantly inhibited under cobalamin deficiency. The response mechanism for this phenomenon was revealed through combined lipidomic and transcriptomic analysis. Although cell growth was inhibited under cobalamin deficiency, the genes encoding key enzymes in central carbon metabolism were still up‐regulated to provide precursors (Acetyl‐CoA) and reducing power (NADPH) for the synthesis and accumulation of fatty acids. Moreover, the main lipid subclasses observed during cobalamin deficiency were glycerolipids (including glycerophospholipids), with EPA primarily distributed in them. The genes involved in the biosynthesis of these lipid subclasses were significantly up‐regulated, such as the key enzymes in the Kennedy pathway for the synthesis of triglycerides. Thus, this study provided insights into the specific response of Schizochytrium sp. to cobalamin deficiency and identified a subset of new genes that can be engineered for modification.
Graphical and Lay Summary
Under cobalamin deficiency, Schizochytrium sp. exhibits metabolic adaptations to enhance eicosapentaenoic acid (EPA) synthesis. Transcriptomic and lipidomic analyses reveal upregulation of key genes involved in fatty acid synthesis pathways, particularly the polyketide synthase (PKS) pathway. This metabolic shift leads to increased EPA content and altered lipid composition, presenting potential targets for genetic engineering to enhance EPA production.
For the increasing demand for lipids and terpenoids in humans, biological fermentation has become an attractive choice due to the safety and sustainability. Thraustochytrids have been identified as ...promising producers of polyunsaturated fatty acids because of their high lipid content and simple fatty acid composition. In addition, thraustochytrids are also potential producers of terpenoids for their completed mevalonate pathway. Chemical regulators can be used to stimulate or inhibit metabolic pathways, which are equivalent to effects of overexpression and suppression approaches. The application of chemical regulators is potentially an easy and practical approach to improve the lipid and terpenoid yield in thraustochytrids, which has become a research focus. In this review, the mechanisms of chemical regulators promoting lipid and terpenoid biosynthesis in thraustochytrids are elucidated. Various chemical regulators which can directly enhance the biosynthesis of lipids and terpenoids are summarized depending on the type of chemicals. In addition, some chemical regulators are demonstrated to indirectly improve lipid and terpenoid yield by reducing the conversion of metabolites and reducing oxidative stress. Therefore, the addition of chemical regulators can be a useful alternative strategy for improving lipid and terpenoid accumulation in large-scale cultivation of thraustochytrids.
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•Natural seawater was applied in DHA production to reduce consumption of freshwater.•Fermentation wastewater was recycled to replace organic nitrogen source and water.•A pH control ...strategy using waste ammonia was developed in recycling fermentation.•46.4 g/L DHA yield was obtained in 50 L bioreactor by this fermentation strategy.
The fermentation production of docosahexaenoic acid (DHA) is an industrial process with huge consumption of freshwater resource and nutrient, such as carbon sources and nitrogen sources. In this study, seawater and fermentation wastewater were introduced into the fermentation production of DHA, which could solve the problem of fermentation industry competing with humans for freshwater. In addition, a green fermentation strategy with pH control using waste ammonia, NaOH and citric acid as well as FW recycling was proposed. It could provide a stable external environment for cell growth and lipid synthesis while alleviating the dependence on organic nitrogen sources of Schizochytrium sp. It was proved that this strategy has good industrialization potential for DHA production, and the biomass, lipid and DHA yield reached to 195.8 g/L, 74.4 g/L and 46.4 g/L in 50 L bioreactor, respectively. This study provides a green and economic bioprocess technology for DHA production by Schizochytrium sp.
This study aims to develop a fermentation method instead of fruiting body extraction for Cordyceps polysaccharide (CP). The fermentation characteristics of P. dubia at different pH were inspected. ...The mechanism of microcycle conidiation of P. dubia was activated under pH 9.0 and produced yeast-like spores. A pH-shift strategy was raised based on the analysis of fermentation kinetics parameters. And, yeast-like spores were used as fermentation seeds to increase culture density. To further improve efficiency, a fed-batch fermentation with a pH-shift strategy was executed, CP production reached 13.54 g/L, with the productivity of 0.42 g/(L d), and the specific rate of CP to biomass was increased to 0.27, which improved by 47.6 %, 64.3 % and 97.1 % respectively, compared with fermentation without process controls. And, CP from fermented and extracted had the same monosaccharide composition except for differences in molecular weight. This study provides a feasible strategy for the efficient preparation of CP through spores fermentation.
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•Microcycle conidiation of P. dubia was activated at pH 9.0 and produced spores.•A spores fermentation method was first introduced to the production of CP.•The stage kinetic characteristics of CP fermentation by P. dubia were proposed.•A maximum CP yield of 13.54 g/L was gained in fed-batch with pH-shift strategy.
Liquid submerged fermentation is an effective strategy to achieve large-scale production of active ingredients by macrofungi, and controlling mycelium morphology is a key factor restricting the ...development of this technology. Mining for superior morphological regulatory factors and elucidation of their regulatory mechanisms are vital for the further development of macrofungal fermentation technology. In this study, microparticles were used to control the morphology of
Paraisaria dubia
(
P. dubia
) in submerged fermentation, and the underlying regulatory mechanisms were revealed by transcriptomic. The relative frequency of S-type pellet diameter increased significantly from 7.14 to 88.31%, and biomass increased 1.54 times when 15 g/L talc was added. Transcriptome analysis showed that the morphological regulation of filamentous fungi was a complex biological process, which involved signal transduction, mycelium polar growth, cell wall synthesis and cell division, etc. It also showed a positive impact on the basic and secondary metabolism of
P. dubia
. We provided a theoretical basis for controlling the mycelium morphology of
P. dubia
in submerged fermentation, which will promote the development of macrofungal fermentation technology.
Graphical abstract
A new method was developed to determine the contents of PAHs in fish by gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS) with SRM mode. In this method, ultrasonic extraction with ...hexane/dichloromethane (1:1v/v) and Florisil column cleaning with hexane/acetone (4:1v/v) was used as the sample pretreatment. Recoveries of the 16 PAHs for spiked samples were between 68.5% and 106.3%, the relative standard deviations (RSD) were between 0.1% and 17.8%. The limits of detection (LODs) ranged from 0.024-0.06 μg/kg and the limits of quantitation (LOQs) ranged from 0.08-0.2 μg/kg. The influence of different elution solvent to recovery and the matrix effect were also discussed.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A new method was developed for the determination of 12 polychlorinated biphenyls (PCBs) in meat and sea food by gas chromatography coupled to triple quadrupole mass spectrometry using selected ...reaction monitoring technique. The method was based on ultrasonic extraction and florisil column cleaning up. Recoveries of the 12 PCBs ranged from 70.4 % to 100.6 % and the relative standard deviations were from 0.5 % to 12.6 %. The limits of detection ranged from 0.006 to 0.009 μg/kg and the limits of quantitation ranged from 0.02 to 0.03 μg/kg. Eight meat and sea food samples were analyzed for the analysis of the polychlorinated biphenyls using the proposed method.
Arsenic trioxide(ATO) is used as a chemotherapeutic agent for the treatment of acute promyelocytic leukemia. However, increasing drug resistance is reducing its efficacy. Therefore, a better ...understanding of ATO resistance mechanism is required. In this study, we established an ATO-resistant human epidermoid carcinoma cell line, KB/ATO, from its parental KB-3-1 cells. In addition to ATO, KB/ATO cells also exhibited cross-resistance to other anticancer drugs such as cisplatin, antimony potassium tartrate, and 6-mercaptopurine. The arsenic accumulation in KB/ATO cells was significantly lower than that in KB-3-1 cells. Further analysis indicated that neither application of P-glycoprotein inhibitor, breast cancer resistant protein(BCRP) inhibitor, or multidrug resistance protein 1(MRP1) inhibitor could eliminate ATO resistance. We found that the expression level of ABCB6 was increased in KB/ATO cells.In conclusion, ABCB6 could be an important factor for ATO resistance in KB/ATO cells. The ABCB6 level may serve as a predictive biomarker for the effectiveness of ATO therapy.
Kaempferol alleviates oxidative stress injury of human keratinocytes ZOU Xue-lian, HU Wen, LEI Zi-xian, WANG Hong-juan, XU Chen, Halina HAIRUOLA, KANG Xiao-jing
Ji chu yi xue yu lin chuang = Jichu yixue yu linchuang = Basic medical sciences and clinics,
08/2021, Letnik:
41, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Objective To explore the antioxidant effect and mechanism of kaempferol(KP), a component of Vernonia anthelmintica (L.) Willd., in human immortalized keratinocytes (HaCaT). Methods Using selective ...reaction/multiple response monitoring technique for quantitative analysis of the flavonoids in the seeds of Vernonia anthelmintica (L.) Willd.. HaCaT cells were divided into control group, model group(HaCaT cells were treated with AAPH to establish the oxidative stress model), low-, middle- and high-dose KP intervention groups.CCK-8 assay for proliferation, RT-qPCR was used for checking the expression of Nrf2, HO-1, NQO1, GCLC and GCLM mRNA, Western blot was used for checking the expression of Nrf2 protein. Results 1)The content of total flavonoids of Vernonia anthelmintica (L.) Willd.. was 0.97 g/100 g, and a total of 36 flavonoid compounds were quantified, the content of KP was 62.96 ng/100 g. 2)The optimum concentration of AAPH for constructing oxidative stress model was 25 mmol/L, and when the concentration of K
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