优化前体供给与细胞膜通透性强化大肠杆菌合成麦角硫因

麦角硫因（Ergothioneine,ERG）具有抗氧化、抗炎、辐射保护等多种生理功能,广泛应用于食品、医药和化妆品领域。微生物发酵生产麦角硫因具有极大潜力,然而,由于工程菌株前体供应不充足等因素,麦角硫因的发酵质量浓度以及生产强度低下。作者旨在探究麦角硫因生产不同阶段中的前体限制,并通过优化前体供应解除限制,进而提高大肠杆菌麦角硫因合成能力。在证明组氨酸是限制麦角硫因合成的关键因素基础上,通过优化组氨酸供给,麦角硫因在摇瓶水平的发酵质量浓度达到175.81 mg/L;通过正交试验组合优化了半胱氨酸、柠檬酸铁胺和维生素B6的添加量,发酵质量浓度提高至182.61 mg/L;通过优化甲基供体的添加（1.5 g/L甲硫氨酸与0.6 g/L甜菜碱）以及通过添加0.2 g/dL的CaCl2提高细胞膜通透性,麦角硫因的发酵质量浓度最终提高至243.06 mg/L。采用分批补料发酵培养108 h后,麦角硫因在3 L发酵罐上的发酵水平达到2.01 g/L,生产强度为18.61 mg/（L·h）,为麦角硫因的规模化工业生产奠定了基础。     

酿酒酵母表达侧耳源单基因生物合成麦角硫因

运用生物信息学方法对侧耳属蘑菇（平菇、杏鲍菇和白灵菇）的麦角硫因合成酶基因Egt 1进行挖掘,对其蛋白结构和功能进行预测,并构建酿酒酵母表达载体,在酿酒酵母EC 1118中进行表达研究。结果表明：克隆得到侧耳属平菇、杏鲍菇和白灵菇麦角硫因合成基因PoEgt 1、PeEgt 1和PtEgt 1,三者核苷酸序列同源性为97.03%,氨基酸序列同源性为97.93%,联合菌体破碎法并通过体外酶促反应后检测到麦角硫因,产量为（2.5±0.08）mg/L,证明了该基因具有单基因合成麦角硫因的活性。     

蘑菇可预防老年痴呆

正近日,美国宾夕法尼亚州立大学的一项研究显示,多吃蘑菇可预防老年痴呆症。宾夕法尼亚州立大学食品学名誉教授罗伯特·贝尔曼称,蘑菇之所以有此功效,是由于它含有大量特殊抗氧化剂——麦角硫因和谷胱甘肽。肝脏、黑豆、蛋黄和燕麦麸等食物也含有这些抗氧化剂,但蘑菇中含量最高。     

烹调中如何减少维生素C的损失

维生素也叫维他命，是生物体为维持正常生理功能，从食物中获得的一种微量有机化合物。维生素Ｃ也称抗坏血酸或抗坏血病维生素，是人体所必需的一种水溶性维生素。 维生素Ｃ对人体有着重要的生理功能。它能维持生物膜的稳定状态和促进伤口愈合，能参与细胞间质生成并有解毒作用，能增加肠道内铁的吸收，能使许多致癌物质失去致癌作用，因此具有抗癌的功效……。 因人体内缺乏合成维生素Ｃ的酶，故人体内不能合成维生素Ｃ。因此，人体维生素Ｃ的全部需要量均要从食物中摄取。 维生素Ｃ含量较多的食物有新鲜蔬菜、水果等，而其中尤以红枣、山…     

蘑菇可预防老年痴呆

正近日,美国宾夕法尼亚州立大学的一项研究显示,多吃蘑菇可预防老年痴呆症。宾夕法尼亚州立大学食品学名誉教授罗伯特·贝尔曼称,蘑菇之所以有此功效,是由于它含有大量特殊抗氧化剂——麦角硫因和谷胱甘肽。肝脏、黑豆、蛋黄和燕麦麸等食物也含有这些抗氧化剂,而蘑菇中含量最高。在研究人员选取的13种蘑菇中,牛肝菌所含的量是最高的,白蘑菇等常见蘑菇中含量相对较少,但     

植物油与维生素E

人们一日三餐都要吃油,食油内含有大量的脂肪。脂肪的主要生理功能是提供热能和构成人体的脂肪组织。然而由于大量摄取动物性脂肪,会导致胆固醇体内吸收和蓄积过多,高血压、动脉硬化、心脏病、糖尿病等日益增多,唤起人们普遍注重饮食与健康问题。摄取植物油可以减少血中胆固醇含量,减少上述疾病的发生。植物油中含有多量不饱和脂肪酸,可帮助清除血管中胆固醇,是构成机体内组织必需成分。因不饱和脂肪酸,在动物体内无法自己合成,必须靠从食物中摄取,所以称     

营养因子强化麦角硫因生物合成的研究

以糙皮侧耳CGMCC 6232菌丝体深层发酵制备麦角硫因,通过向发酵培养基中添加不同种类及浓度的无机盐、维生素、生长调节剂、有机酸、氨基酸等营养因子,考察对麦角硫因合成积累的影响,研究可能的前体氨基酸对麦角硫因生物合成的影响规律。结果表明:添加氯化铵、硝酸铵、叶酸、VB1、吲哚丁酸、丙酮酸、柠檬酸、谷氨酸、蛋氨酸、半胱氨酸、组氨酸和甜菜碱对麦角硫因的合成有一定的促进作用,其中以发酵第4天向发酵液中添加15 mmol/L蛋氨酸最利于麦角硫因的合成,发酵液中麦角硫因的含量达192.4 mg/L,比对照组(102 mg/L)提高了88.6%。     

褪黑素的应用

褪黑素作为一种荷尔蒙,对改善人体神经和内分泌系统具有显著效果。该物质既存在于人体和动物体内,也存在于多种植物中。褪黑素的生理功能,褪黑素在植物体内的含量和褪黑素的提取、测定方法,具有一定的研究价值。     

降血压因子——γ-谷氨酰甲胺的研究进展

γ-谷氨酰甲胺是一种特殊氨基酸,在生物体内发挥重要作用,特别是其具有明显的降低血压功能.本文简要介绍了γ-谷氨酰甲胺在植物、微生物和动物体内的生理功能,并对其化学合成和生物合成的方法进行详细阐述.评述了合成方法的优缺点,提出可能的合成途径,对γ-谷氨酰甲胺开发应用前景进行了展望.     

富含麦角硫因的金针菇提取物对冷冻猪肉糜品质的影响

基于蘑菇中含有麦角硫因等天然抗氧化物质,选取金针菇作为原料,利用醇提取法获得富含麦角硫因的金针菇提取物,将其添加到猪肉糜中（6 g/kg）,冷冻贮藏12周后,通过测定脂肪氧化、蛋白质氧化、核苷酸和感官评价等指标来评价金针菇提取物对冷冻肉糜品质的影响。结果表明,金针菇提取物的麦角硫因含量为15.29 mg/g。在冷冻贮藏的第0、1、4、8和12周,添加金针菇提取物显著降低了肉糜的pH（P<0.05）;显著减缓了猪肉糜的脂肪氧化和蛋白氧化（P<0.05）;显著提高了冷冻肉糜的IMP和AMP含量（P<0.05）,表明添加金针菇提取物可以抑制氧化,可在一定程度上增加鲜味物质的含量,并抑制苦味物质的生成;感官评价结果表明,添加金针菇提取物可以在一定程度上提高冷冻肉糜的风味、滋味、嫩度及整体可接受性。以上结果表明,添加富含麦角硫因的金针菇提取物可以有效延缓猪肉糜冷冻过程中的氧化变质,增强猪肉糜的鲜味,提高猪肉糜的感官品质。因此,它可作为天然抗氧化剂应用于肉类保藏。     

破囊壶菌属微生物中超长链多不饱和脂肪酸的生物合成及其代谢工程应用

超长链多不饱和脂肪酸（VLCPUFAs）包括ARA、EPA、DHA等不但能营养机体,又具有独特生理功能而受到广泛的关注。破囊壶菌属微生物作为VLCPUFAs主要生产者,是鱼类、贝类等海洋生物富集积累VLCPUFAs的重要来源。许多研究指出,破囊壶菌具有大规模工业化生产VLCPUFAs的潜力。但是,目前对其的生物合成途径和组装机理仍未清楚。该综述从破囊壶菌属微生物的生物合成途径、储藏性脂质的组装机理和提高VLCPUFAs产量的基因工程策略三个方面进行介绍,着重对其VLCPUFAs的生物合成途径,及其油脂组装机理开展详细的介绍,并整理、结合一些较为前沿的研究发现对这些途径研究的潜在应用进行探讨,提高人们对破囊壶菌的生物合成及甘油酯组装途径的认知。研究表明,通过异源表达参与VLCPUFAs合成的基因,能在微生物工程菌和油料作物中产生EPA、DPA和DHA等功能油脂,含量能达到总脂的5%~40%,而通过基因工程敲除或改造破囊壶菌微生物的脂质合成途径基因,能提高破囊壶菌DHA产量约3%~55%。这些实例为指导VLCPUFAs的工业化生产,提供理论依据。     

共轭亚油酸生物合成及其对肠道菌群影响的研究进展

共轭亚油酸(CLA)是一种人和动物自身无法合成但又不可缺少的脂肪酸,它具有抗癌、抗肥胖、抗动脉粥样硬化、抗糖尿病等潜在生理功能,被广泛用作食品营养补充剂。由于天然CLA来源较少、化学合成副产物较多,而利用乳酸菌生物合成的CLA结构单一且转化效率高,是一种有前景的合成方法。目前微生物将亚油酸(LA)转化为CLA的机制主要有2种,即以瘤胃微生物为主的生物氢化合成和乳酸菌为代表的多酶系合成。现有研究表明,CLA具有调节肠道菌群的作用,并指出其潜在生理功能可能与其对肠道微生态的影响密切相关。文章总结了CLA生物合成和影响因素,分析了CLA的生物合成机制以及其对肠道菌群的调节作用,为进一步筛选出高产CLA菌株和CLA的产业化应用提供理论依据。     

Alginate Oligosaccharides: Production,Biological Activities,and Potential Applications

Alginate, a group of polyuronic saccharides, has been widely used in both pharmaceutical and food industries due to its unique physicochemical properties as well as beneficial health effects. However, the potential applications of alginate are restricted because of its low water solubility and high solution viscosity when significant concentrations are needed, particularly in food products. Alginate oligosaccharides (AOS), oligomers containing 2 to 25 monomers, can be obtained via hydrolysis of glycosidic bonds, organic synthesis, or through biosynthesis. Generally, AOS have shorter chain lengths and thus improved water solubility when compared with higher molecular weight alginates of the same monomers. These oligosaccharides have attracted interest from both basic and applied researchers. AOS have unique bioactivity and can impart health benefits. They have shown immunomodulatory, antimicrobial, antioxidant, prebiotic, antihypertensive, antidiabetic, antitumor, anticoagulant, and other activities. As examples, they have been utilized as prebiotics, feed supplements for aquaculture, poultry, and swine, elicitors for plants and microorganisms, cryoprotectors for frozen foods, and postharvest treatments. This review comprehensively covers methods for AOS production from alginate, such as physical/chemical methods, enzymatic methods, fermentation, organic synthesis, and biosynthesis. Moreover, current progress in structural characterization, potential health benefits, and AOS metabolism after ingestion are summarized in this review. This review will discuss methods for producing and modified AOS with desirable structures that are suited for novel applications.     

麦角硫因的生物活性及其在食品领域中应用研究进展

麦角硫因（ergothioneine, EGT）是一种天然无毒的稀有氨基酸衍生物，广泛存在于各种食用菌中，前期研究已经证明其具有优异的抗氧化活性。目前研究人员致力于挖掘EGT更多新的生物活性功能，发现EGT在减轻炎症反应、细胞保护、预防糖尿病和心血管疾病、干预神经退行性疾病、治疗精神性疾病以及延缓衰老等方面也具有良好效果。本文主要综述了EGT的生物活性及其在食品领域中应用的研究进展，重点论述了对于EGT生物活性研究中较成熟的领域，补充了当前EGT在预防和治疗疾病方面的新发现，提出了EGT作为食品抗氧化剂、食品护色剂和膳食添加剂等在食品领域中发挥作用的可能性，为相关功能性食品的研发及EGT其在食品领域中的深层次研究和应用提供一定参考。     

Biotechnological production of zeaxanthin by microorganisms

BackgroundZeaxanthin is a natural xanthophyll carotenoid that is widely produced by plants, algae and microorganisms and plays a critical role in the prevention of age-related eye diseases, such as macular degeneration and cataracts. Zeaxanthin is also used in the food, pharmaceutical and nutraceutical industries because of its strong antioxidant and anti-cancer properties. To date, zeaxanthin has been primarily produced by extraction from natural resources, especially plants, which is costly and environmentally unfriendly. The biosynthesis of zeaxanthin by microorganisms has been reported in lots of works to provide another potential route for zeaxanthin production.Scope and approachIn this review, we discuss the zeaxanthin biosynthetic pathway, naturally occurring zeaxanthin-accumulating microorganisms containing bacteria and microalgae, the optimization of fermentation conditions using these microorganisms, and zeaxanthin production using microbial cells factory constructed by metabolic engineering. The different metabolic engineering strategies and the zeaxanthin-accumulating level of the reviewed wild and engineered microorganisms are also considered. Furthermore, this work presents perspectives concerning the microbial production of zeaxanthin, especially the trends to construct the metabolically engineered microorganisms for zeaxanthin production.Key findings and conclusionsTo date, all the reported wild zeaxanthin-accumulating microorganisms belong to either bacteria or microalgae, while most of the reported engineering microorganisms for zeaxanthin production are Escherichia coli or yeast. A feasible strategy for zeaxanthin production is the use of metabolic engineering to construct a zeaxanthin-accumulating microbial cells factories followed by the optimization of fermentation with the engineered strain. Besides the simple overexpression of the biosynthesizing genes, the dynamic regulation of the constructed pathway has also been used for zeaxanthin production by metabolic engineering. Construction of better microbial cells factories which produce more zeaxanthin will profit from the breakthrough of the following fields: Introduction of higher plant zeaxanthin biosynthesizing genes into microorganisms; Characterization of novel zeaxanthin pathway genes from the wild microorganisms producing high level of zeaxanthin; Deep investigation of the farnesyl diphosphate formation pathway; Construction of microbial host with weak antioxidative capacity.     

抗坏血酸、谷胱甘肽参与的信号转导途径在提高植物食品营养品质中的作用

ASA(抗坏血酸)、GSH(还原型谷胱甘肽)是植物体内一类低分子量、可溶性的抗氧化剂。在动植物体内,GSH合成途径大致相同而ASA合成途径却差别很大。通过调控与二者合成有关的酶进而提高它们在植物食品中的含量具有很大的应用前景。然而,众多的环境因素,尤其是氧化胁迫通过一定的信号转导途径对植物体内与ASA、GSH合成相关酶的影响很大,酶活性的变化又影响了体内ASA、GSH含量。因此深入研究植物体内GSH、ASA参与的信号转导途径对提高植物食品营养品质具有重要意义。     

利用洛伐他汀选育高产β-胡萝卜素的三孢布拉霉菌株

β-胡萝卜素为类萜化合物，是重要的VA的前体，并具有较强的抗氧化作用，在食品、保健品、化妆品以及医药领域具有重要用途。利用三孢布拉霉（Blakeslea trispora）发酵生产天然β-胡萝卜素最有应用前景。我们利用含有洛伐他汀（lovastatin）和OP乳化剂或脱氧胆酸钠（SDC）的平板实现了对高产菌株的选育，方法简单，效果明显。     

Influence of Innovative Processing on γ‐Aminobutyric Acid (GABA) Contents in Plant Food Materials

Over the last several decades, γ‐aminobutyric acid (GABA) has attracted much attention due to its diverse physiological implications in plants, animals, and microorganisms. GABA naturally occurs in plant materials and its concentrations may vary considerably, from traces up to μmol/g (dry basis) depending on plant matrix, germination stage, and processing conditions, among other factors. However, due to its important biological activities, considerable interest has been shown by both food and pharmaceutical industries to improve its concentration in plants. Natural and conventional treatments such as mechanical and cold stimulation, anoxia, germination, enzyme treatment, adding exogenous glutamic acid (Glu) or gibberellins, and bacterial fermentation have been shown effective to increase the GABA concentration in several plant materials. However, some of these treatments can modify the nutritional, organoleptic, and/or functional properties of plants. Recent consumer demand for food products which are “healthy,” safe and, having added benefits (nutraceuticals/functional components) has led to explore new ways to improve the content of bioactive compounds while maintaining desirable organoleptic and physicochemical properties. Along this line, nonthermal processing technologies (such as high‐pressure processing, pulsed electric fields, and ultrasound, among others) have been shown as means to induce the biosynthesis and accumulation of GABA in plant foods; and the main findings so far reported are presented in this review. Moreover, the most novel tools for the identification of metabolic response in plant materials based on GABA analysis will be also described.     

番茄红素及其生物合成途径的研究

介绍番茄红素具有的理化特性和生理功能,植物中番茄红素的生物合成途径及其调控。由于番茄红素的特定分子结构,使其具有抗癌、保护皮肤、延缓衰老等功能特性,是对人类健康有益的食物成分。而随着番茄红素合成途径的阐明及对其合成调控的研究,运用基因工程手段调控番茄红素的生物合成已成为现实。     

Computational and experimental validation of antioxidant properties of synthesized bioactive ferulic acid derivatives

Ferulic acid, a well-known natural phenolic compound, is considerably reported for its hydroxyl and peroxyl radical scavenging activities. However, the antioxidant capacity of ferulic acid is limited by its relatively low solubility in hydrophobic media thereby preventing its application for autoxidation of fats and oils. To this end, several research efforts are being made to maximize the therapeutic benefits of ferulic acid and these efforts included but not limited to structural modification of ferulic acid to produce its derivatives. In this study, we synthesized ester and amide derivatives of ferulic acid and evaluated them for in vitro antioxidant potential as well as molecular docking properties. Data revealed that ferulic ester and amide derivatives had excellent antioxidant capacity and demonstrated strong inhibitory potential. Analysis of molecular docking indicated ferulic ester as potent inhibitor of target proteins in breast cancer as well as in oxidative stress. Taken together, the findings support potent antioxidant properties by these ferulic derivatives. Findings may become relevant where structural modification to enhance physico-chemical properties without compromising the antioxidant and/or medicinal potential are desirable.