青蒿内生真菌研究进展

植物内生真菌可以产生与宿主植物相同或相似的次生代谢产物,已成为活性化合物生产和发现新化合物的重要来源。为了解青蒿内生真菌的潜在应用价值,介绍了青蒿内生真菌的生物多样性、生物活性和部分次生代谢产物,并展望了未来的研究方向,以期为进一步开发利用青蒿内生真菌提供参考。     

环氧角鲨烯合成通路在大肠杆菌中的构建和优化

三萜类化合物是一类广泛应用于医药、保健和化妆品等行业的天然产物,具有巨大的商业价值.生物合成三萜类化合物依赖于环氧角鲨烯的高效合成.角鲨烯环氧化酶是整个合成途径中的关键酶,其催化NADPH依赖的环氧化反应将角鲨烯转变为环氧角鲨烯.通过筛选不同来源的角鲨烯环氧化酶,截短的大鼠角鲨烯环氧化酶(RnSETC)在大肠杆菌Esc...     

乳清蛋白生物活性肽研究进展

以乳清蛋白为原料,经过酶解或发酵等方法可以获得独特理化性质的生物活性肽。乳清蛋白生物活性肽来源广、活性强、分子量小,在食品和医药行业有很高的应用研究价值,已经成为研究热点。随着制备、分离纯化以及鉴定技术的不断发展和成熟,越来越多的乳清蛋白生物活性肽被发现。本研究主要综述了乳清蛋白生物活性肽的制备、分离纯化、鉴定方法以及生物功能,并展望了乳清蛋白生物活性肽应用前景,以期为功能性乳清蛋白生物活性肽产品的开发与应用提供参考。     

乳酪蛋白源生物活性肽的研究进展

酪蛋白是生物活性肽的重要来源,可以通过体内的胃肠消化和食品加工过程中的酶解将其释放出来。乳酪蛋白源的生物活性肽的生物学意义、对人类健康的影响和其在新型功能性食品加工中的作用具有重要的研究价值。     

乳清蛋白及其生物活性肽血压调节功能研究进展

乳清蛋白既是优质蛋白来源，也是抗高血压生物活性肽的理想来源，开发具有调节血压功效的蛋白多肽类产品对未来临床高血压防治将发挥重要作用。文章综述了乳清蛋白生物活性肽血压调节功能的基本机制和研究现状，并对其未来发展趋势和应用前景进行了讨论。     

间充质干细胞来源外泌体在骨关节炎治疗中的作用

骨关节炎(OA)是最常见的慢性退行性骨关节疾病,目前对骨关节炎的治疗还没有特效疗法。间充质干细胞(MSC)对软骨修复有较好的疗效,间充质干细胞来源外泌体可能在这一治疗过程中发挥重要作用。外泌体是细胞间的通讯载体,能在细胞间传递生物活性脂质、核酸以及蛋白质等生物活性分子对骨关节炎产生一定影响。本文就探讨间充质干细胞来源的外泌体治疗骨关节炎过程中的作用机制与可行性做出综述。     

Nigrospora 属真菌化学成分及生物活性研究进展CSCD

Nigrospora属真菌是常见的药用动植物内生真菌,其次级代谢产物结构多样且生物活性显著,是药用活性物质的重要来源。本文对1997年至2021年报道的Nigrospora属真菌化学成分及其生物活性首次进行了系统综述,涵盖聚酮、蒽醌、萜、甾体和生物碱等199个化合物,并总结其抗菌、抗氧化、抗病毒、抗糖尿病和抗肿瘤等生物活性,以期为该属真菌药用成分的深度开发提供参考。     

产角鲨烯细胞工厂的构建及关键基因的筛选、克隆与表达

角鲨烯因具有很强的抗氧化、抗菌和抗肿瘤活性,被普遍应用于医药、保健品和化妆品等领域。文中在实验室构建的高效合成萜类化合物底盘菌株工作的基础上,以角鲨烯为目标产物,通过过表达法尼基焦磷酸合酶基因ispA得到高效合成三萜化合物的底盘菌株;然后对原核生物来源的角鲨烯合酶进行系统发育分析、筛选、克隆和表达,得到两株高效合成角鲨烯的大肠杆菌Escherichia coli工程菌株。其中,导入来源于嗜热蓝细菌Thermosynechococcus elongatus和深蓝聚球蓝细菌Synechococcus lividus的角鲨烯合酶的工程菌株,角鲨烯产量分别达到 (16.5±1.4) mg/g (细胞干重含量,后同) 和 (12.0±1.9) mg/g,发酵液浓度达到 (167.1±14.3) mg/L和(121.8±19.5) mg/L。相比于当前普遍使用的人源角鲨烯合酶及初代菌株,来源于T. elongatus和S. lividus的角鲨烯合酶分别使角鲨烯产量大幅提升了3.3倍和2.4倍,为原核细胞异源合成角鲨烯打下坚实的基础。     

酸性成纤维细胞生长因子研究进展

酸性成纤维细胞生长因子(acidic fibroblast growth factors,aFGF)是成纤维细胞生长因子家族(fibroblast growth factors,FGF)中的一员,是一种重要的生长因子,具有广泛的生物活性和临床应用价值.本文概述了aFGF的结构与功能关系和信号传导通路,阐述了aFGF生理功能与生物学效应以及潜在临床应用价值.     

γ-亚麻酸的研究进展

γ-亚麻酸(GLA)是人体必需的具有多种特殊生理功能的多不饱和脂肪酸,它在机体的物质代谢和生理调控上发挥着十分重要的作用,已被世界上许多国家用于医药工业、生产功能性食品和美容护肤品等多种领域.该文综述了GLA的生物活性、动植物来源、微生物资源及应用基因工程技术改造植物、微生物生产GLA的研究进展.提出了目前常用的三种生产GLA的方法存在的问题.认为利用基因工程技术改良油料作物生产GLA的理论和方法已经建立,具有广阔的应用前景.     

Squalene production in the cell suspension cultures of Indian sandalwood (<Emphasis Type="Italic">Santalum album</Emphasis> L.) in shake flasks and air lift bioreactor

Squalene has emerged as a specialty chemical being important in nutraceutical, pharmaceutical, vaccine and cosmetic industries due to the anticancer, antioxidant, skin hydrating, immune stimulating and emollient activities. The main source of squalene is shark liver oil, but alternate sources are being sought to secure sustainable supply of squalene and conserve the marine sources. The present work was carried out with the aim of generation of this compound in the cell suspension cultures of sandalwood, a medicinally important plant rich in sesquiterpenes. To achieve this, highly proliferating cell lines of sandalwood were generated by medium optimization. Accumulation of squalene in the cells was studied in a time dependent manner in shake flasks and bioreactor. In shake flask experiments, a significant amount of 3.2 mg/g dry weight was accumulated in 6 weeks of culture whereas the cells performed much better in bioreactor where squalene accumulation was found to be 5.5 mg/g dry weight in 4 weeks. Enzymes of lower terpenoid pathway namely hydroxy-3 methylglutaryl-coenzyme A reductase, farnesyl diphosphate synthase and squalene synthase showed a positive correlation with the product accumulation as evident from GC analysis of the reaction products and terpenoids accumulated. The findings of present work describe a high potential for commercial application since the marine sources have pollution concerns, vegetal sources are limited and the compound offers great hope in prevention of human chronic diseases like cancer. To our knowledge this is the first report about squalene generation in medicinally important sandalwood plant cell suspensions.     

Identification of novel mammalian squalene synthase inhibitors using a three-dimensional pharmacophore

Squalene synthase (E.C. 2.5.1.21) catalyses the reductive dimerisation of farnesyl diphosphate in a [1-4] head to head fashion to form squalene, and is the first committed step in cholesterol biosynthesis. Specific inhibitors of squalene synthase would inhibit cholesterol formation and allow production of other important compounds derived from the cholesterol biosynthetic pathway, namely the ubiquinones (co-enzyme Q(10)), dolichol, and would also allow the isoprenylation process of ras by farnesyl-protein transferase. The construction of a hypothetical squalene synthase three-dimensional pharmacophore is presented. It serves as a template for the identification of several new potential classes of inhibitors. The synthesis, anti-microbial and mammalian pig liver squalene synthase activities of analogues based on the bicyclo[3.2.0]heptane and bicyclo[3.3.0]octane ring systems are reported. Analogues of the latter system are pro-drug type inhibitors and exhibit promising biological activity.     

High-level recombinant production of squalene using selected <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> strains

For recombinant production of squalene, which is a triterpenoid compound with increasing industrial applications, in microorganisms generally recognized as safe, we screened Saccharomyces cerevisiae strains to determine their suitability. A strong strain dependence was observed in squalene productivity among Saccharomyces cerevisiae strains upon overexpression of genes important for isoprenoid biosynthesis. In particular, a high level of squalene production (400 ± 45 mg/L) was obtained in shake flasks with the Y2805 strain overexpressing genes encoding a bacterial farnesyl diphosphate synthase (ispA) and a truncated form of hydroxyl-3-methylglutaryl-CoA reductase (tHMG1). Partial inhibition of squalene epoxidase by terbinafine further increased squalene production by up to 1.9-fold (756 ± 36 mg/L). Furthermore, squalene production of 2011 ± 75 or 1026 ± 37 mg/L was obtained from 5-L fed-batch fermentations in the presence or absence of terbinafine supplementation, respectively. These results suggest that the Y2805 strain has potential as a new alternative source of squalene production.     

The isolation and characterization of Pseudozyma sp. JCC 207, a novel producer of squalene

In examining the production of valuable compounds by marine microorganisms, we isolated a novel yeast strain that produces a large amount of squalene and several polyunsaturated fatty acids. Molecular and phylogenetic analyses of the ribosomal DNA suggest that the isolate belongs to the genus Pseudozyma, which comprises ustilaginomycetous anamorphic yeasts. The nucleotide sequence of an internally transcribed spacer region from isolate Pseudozyma sp. JCC207 showed 98% similarity with those of Pseudozyma rugulosa and Pseudozyma aphidis, which are close relatives of the isolate. In considering use of Pseudozyma sp. JCC207 for squalene production, the efficiency of squalene production was investigated under different conditions. Glucose was the best carbon source for the production of squalene. In the presence of yeast extract, squalene production was activated and an optimum ratio of glucose to yeast extract was 4.5. For the optimal squalene production, the concentration of glucose was 40 g l⁻¹ and the best nitrogen source was sodium nitrogen. Pseudozyma sp. JCC207 was shown to produce up to 5.20 g/L of biomass and 340.52 mg/L of squalene. In an optimal condition, the content and yield of squalene produced by Pseudozyma sp. JCC207 were much greater than those obtained from microorganisms previously reported as squalene producers. We identified, classified, and characterized Pseudozyma sp. JCC207 as a novel squalene producer. The squalene production rate of Pseudozyma sp. JCC207 makes it an ideal candidate for the commercialization of microbial squalene.     

Production of squalene by microbes: an update

Squalene, a naturally occurring linear triterpene formed via MVA or MEP biosynthetic pathway, is widely distributed in microorganisms, plants and animals. At present, squalene is used extensively in the food, cosmetic and medicine industries because of its antioxidant, antistatic and anti-carcinogenic properties. Increased consumer demand has led to the development of microbial bioprocesses for the commercial production of squalene, in addition to the traditional methods of isolating squalene from the liver oils of deep-sea sharks and plant seed oils. As knowledge of the biosynthetic enzymes and of regulatory mechanisms modulating squalene production increases, opportunities arise for the genetic engineering of squalene production in hosts. In this review, we present the various strategies used up to date to improve and/or engineer squalene production in microbes and analyze yields.     

Influence of squalene on lipid particle/droplet and membrane organization in the yeast Saccharomyces cerevisiae

In a previous study (Spanova et al., 2010, J. Biol. Chem., 285, 6127-6133) we demonstrated that squalene, an intermediate of sterol biosynthesis, accumulates in yeast strains bearing a deletion of the HEM1 gene. In such strains, the vast majority of squalene is stored in lipid particles/droplets together with triacylglycerols and steryl esters. In mutants lacking the ability to form lipid particles, however, substantial amounts of squalene accumulate in organelle membranes. In the present study, we investigated the effect of squalene on biophysical properties of lipid particles and biological membranes and compared these results to artificial membranes. Our experiments showed that squalene together with triacylglycerols forms the fluid core of lipid particles surrounded by only a few steryl ester shells which transform into a fluid phase below growth temperature. In the hem1? deletion mutant a slight disordering effect on steryl esters was observed indicated by loss of the high temperature transition. Also in biological membranes from the hem1? mutant strain the effect of squalene per se is difficult to pinpoint because multiple effects such as levels of sterols and unsaturated fatty acids contribute to physical membrane properties. Fluorescence spectroscopic studies using endoplasmic reticulum, plasma membrane and artificial membranes revealed that it is not the absolute squalene level in membranes but rather the squalene to sterol ratio which mainly affects membrane fluidity/rigidity. In a fluid membrane environment squalene induces rigidity of the membrane, whereas in rigid membranes there is almost no additive effect of squalene. In summary, our results demonstrate that squalene (i) can be well accommodated in yeast lipid particles and organelle membranes without causing deleterious effects; and (ii) although not being a typical membrane lipid may be regarded as a mild modulator of biophysical membrane properties.     

Influence of squalene on lipid particle/droplet and membrane organization in the yeast Saccharomyces cerevisiae

In a previous study (Spanova et al., 2010, J. Biol. Chem., 285, 6127-6133) we demonstrated that squalene, an intermediate of sterol biosynthesis, accumulates in yeast strains bearing a deletion of the HEM1 gene. In such strains, the vast majority of squalene is stored in lipid particles/droplets together with triacylglycerols and steryl esters. In mutants lacking the ability to form lipid particles, however, substantial amounts of squalene accumulate in organelle membranes. In the present study, we investigated the effect of squalene on biophysical properties of lipid particles and biological membranes and compared these results to artificial membranes. Our experiments showed that squalene together with triacylglycerols forms the fluid core of lipid particles surrounded by only a few steryl ester shells which transform into a fluid phase below growth temperature. In the hem1? deletion mutant a slight disordering effect on steryl esters was observed indicated by loss of the high temperature transition. Also in biological membranes from the hem1? mutant strain the effect of squalene per se is difficult to pinpoint because multiple effects such as levels of sterols and unsaturated fatty acids contribute to physical membrane properties. Fluorescence spectroscopic studies using endoplasmic reticulum, plasma membrane and artificial membranes revealed that it is not the absolute squalene level in membranes but rather the squalene to sterol ratio which mainly affects membrane fluidity/rigidity. In a fluid membrane environment squalene induces rigidity of the membrane, whereas in rigid membranes there is almost no additive effect of squalene. In summary, our results demonstrate that squalene (i) can be well accommodated in yeast lipid particles and organelle membranes without causing deleterious effects; and (ii) although not being a typical membrane lipid may be regarded as a mild modulator of biophysical membrane properties.     

Extension of cell membrane boosting squalene production in the engineered Escherichia coli

Squalene is a lipophilic and non-volatile triterpene with many industrial applications for food, pharmaceuticals, and cosmetics. Metabolic engineering focused on optimization of the production pathway suffer from little success in improving titers because of a limited space of the cell membrane accommodating the lipophilic product. Extension of cell membrane would be a promising approach to overcome the storage limitation for successful production of squalene. In this study, Escherichia coli was engineered for squalene production by overexpression of some membrane proteins. The highest production of 612 mg/L was observed in the engineered E. coli with overexpression of Tsr, a serine chemoreceptor protein, which induced invagination of inner membrane to form multilayered structure. It was also observed an increase in unsaturated fatty acid in membrane lipids composition, suggesting cellular response to maintain membrane fluidity against squalene accumulation in the engineered strain. This study potentiates the capability of E. coli for squalene production and provides an effective strategy for the enhanced production of such compounds.