蛹虫草菌生物合成虫草素的研究进展

蛹虫草Cordyceps militaris是我国传统的药用真菌,虫草素是蛹虫草的主要活性成分,具有抗癌、抗肿瘤、抗病毒等多种生理功能。蛹虫草菌液体发酵是最有希望实现高效生产虫草素的途径,但现阶段生产强度低,亟需应用发酵工程及代谢工程手段提高虫草素产量。文中对液体发酵体系中培养基组分(碳/氮源、前体物质、金属离子等)和培养条件(pH、溶氧量、光照等)对虫草素产量的影响进行了总结,并对虫草素的分离纯化、生物合成基因簇及合成代谢途径进行了阐述,最后探讨了实现虫草素高效生产的关键环节。     

蛹虫草中虫草素的提取及纯化工艺研究

目的:优化从蛹虫草中提取、纯化虫草素的方法并鉴定其纯度.方法和结果:通过3种提取方法的比较,确定了以恒温水浴法作为虫草素规模化提取方法,最佳提取条件为45℃、80％乙醇;同时,确定了ML-7大孔树脂纯化虫草素的工艺,采用该工艺虫草素纯度可达到92％以上,并对纯化虫草素和标准品进行了比较鉴定.结论:该方法提取、纯化的虫草素纯度高,适于虫草素的规模化生产.     

响应面法优化粉被虫草中虫草素的提取工艺

【背景】粉被虫草是民间常用药用真菌,具有抗辐射等多种药理作用,虫草素是其重要的活性物质。【目的】探究粉被虫草中提取虫草素的影响因素,为制取虫草素提供参考。【方法】以虫草素得率为指标,用响应面法优化超声提取工艺。分别考察超声时间、液料比和超声功率对提取效率的影响,在单因素实验基础上进行3因素3水平的响应面分析实验。【结果】最优提取条件为超声时间606 s、液料比45.9:1、超声功率400 W,在此条件下虫草素得率为6.136 mg/g,与模型预测值接近,方程拟合良好。【结论】首次对粉被虫草中虫草素的提取条件进行了研究,将对制取虫草素提供参考,有利于粉被虫草的深度开发利用。     

虫草属真菌中虫草素的超声波提取及其毛细管电泳测定

比较了虫草素的四种提取方法,确定了超声波作用的时间、提取溶剂和样品预处理方式。利用高效毛细管电泳分离、测定了虫草属真菌虫草素的含量,首次报道了九州虫草中虫草素的存在。     

产虫草素真菌资源的研究现状及应用前景

虫草素是中国传统中药冬虫夏草中特有活性成分,它具有抗肿瘤、抗病毒、调节免疫、治疗白血病等多种功效,作为一种新的抗菌素,虫草素已成为一个研究热点。人工合成虫草素过程复杂且产量极低,且会产生毒副产品,含有虫草素的天然材料稀少,高效率提取纯化工艺有待于优化。本文对虫草素的菌株来源、测定方法、提取方法、国内外研究现状及应用前景进行了总结,提出通过资源调查拓宽虫草素来源,找出虫草素合成酶活性更好的菌种,为降低生产成本、提高生物合成量,提供相应的基因和种质资源,为其进入更加广泛的使用范围奠定基础。     

蛹虫草中虫草素、虫草多糖综合提取工艺研究

以蛹虫草为材料．采用超声波水提法、超声波醇提法、水热回流法和醇热回流法4种提取方法选择虫草素和虫草多糖的最优提取办法．并用正交试验方法考察水热回流法中提取温度、提取次数、提取时间、料液比4个因素对虫草素、虫草多精综合提取效率的影响．以确定从蛹虫草中综合提取虫草素、虫草多糖最佳工艺。结果表明．水热回流法是提取虫草多糖和虫草素的最优提取方法．其最佳工艺条件为：用10倍量的水于80℃热回流提取3次．每次90min。     

真菌激发子对提高蛹虫草虫草菌素的作用

研究了不同真菌激发子菌株对提高蛹虫草生物量和虫草菌素含量的影响,其中一株疫霉（Phytophthora sp.)YL提高虫草菌素含量比对照高4倍。机械研磨和80℃高温细胞自溶相结合制备的真菌激发子诱导效果最佳。同一激发子不同浓度对虫草素的诱导实验表明,80μg/ml浓度碳水化合物的真菌激发子诱导蛹虫草产生虫草菌素效果最明显。     

我国虫草产业发展现状、问题及展望——虫草产业发展金湖宣言

虫草是寄生于昆虫、少数真菌和植物体上的一类真菌,是广义虫草属Cordyceps s.l.真菌的总称,是具有营养、保健和医疗功效的宝贵生物资源。目前我国的虫草产业涉及了冬虫夏草Ophiocordyceps sinensis、蛹虫草Cordyceps militaris、蝉花Isaria cicadae及其相关真菌,已经形成了一个巨大的产业,实现了较高的经济价值和社会效益。本文从产业发展历史、产品研发、功效及市场等方面对我国虫草产业发展现状进行了总结,结合最新科学研究进展,分析了虫草产业中存在的一些问题,提出了促进产业健康发展的建议,并对产业前景进行了展望。     

从蛹虫草小麦培养基残渣分离虫草素及提取物对肝癌细胞的抑制效果

从蛹虫草Cordyceps militaris小麦培养基残渣中分离和纯化虫草素,并进行了提取物体外人肝癌细胞Hep G2 (human hepatoma cell line,Hep G2)的抑制作用研究。以蛹虫草小麦培养基残渣为原料,热超声水提取虫草素,探究pH值、温度、浸提时间和超声功率对虫草素的提取效果,用苯乙烯型弱极性大孔吸附树脂(AB-8)柱层析分离、重结晶纯化虫草素,并用高效液相色谱法(high performance liquid chromatography,HPLC)、红外光谱法(infrared spectroscopy,IR)鉴定。虫草素处理肝癌细胞Hep G2后,倒置相差显微镜下观察肝癌细胞形态变化,并用四甲基偶氮唑蓝(methylthiazolyltetrazolium,MTT)法测定细胞生长情况。结果表明：固液比1:50、pH值6.0、温度60 ℃、浸提时间3 h和超声功率300 W时提取效果好。经鉴定,分离提取物的虫草素纯度达到99%以上。不同浓度的虫草素对肝癌细胞Hep G2有明显的抑制作用,且与虫草素浓度和作用时间呈正相关,被抑制的细胞凝集、变圆、碎裂增加。本提取工艺得到的虫草素纯度高,工艺简单易扩大,且提取物对肝癌细胞增殖作用具有明显的抑制作用,为其在功能性食品添加剂方向的应用提供了数据基础。     

真菌激发子对提高蛹虫草虫草菌素的作用*

研究了不同真菌激发子菌株对提高蛹虫草生物量和虫草菌素含量的影响,其中一株疫霉(Phytophthora sp.)YL提高虫草菌素含量比对照高4倍。机械研磨和80℃高温细胞自溶相结合制备的真菌激发子诱导效果最佳。同一激发子不同浓度对虫草素的诱导实验表明, 80mg/ml浓度碳水化合物的真菌激发子诱导蛹虫草产生虫草菌素效果最明显。     

一株产虫草素的冬虫夏草内生真菌 Bionectria ochroleuca OS17

虫草素是一种核苷类似物,具有多种药理作用。利用虫草素产生菌发酵的方式获得虫草素,可能是产生虫草素的一种新方法。为筛选能产虫草素的内生真菌,从中国传统的中药冬虫夏草子实体中共分离得到42株真菌,经PDB液体培养后,采用高效液相色谱（HPLC）鉴定其代谢产物。结果表明：菌株OS17的代谢产物中含有虫草素,且虫草素产量为40.16 mg/L。基于形态学特征和ITS序列分析,菌株OS17被鉴定为淡色生赤壳菌(Bionectria ochroleuca)。这是首次从冬虫夏草中分离得到能产虫草素的生赤壳属,表明了内生真菌具有产生多种生物活性物质的潜力。     

液体培养蛹虫草虫草素和腺苷的代谢量

为提高虫草素和腺苷的代谢量,用高效液相色谱法作检测手段,以二者含量为检测指标,对液体培养的氮源种类、氮源水平、碳源水平、动态变化、培养体系的虫草素及腺苷含量和总量进行研究,结果表明:不仅蚕蛹粉,豆粕和豆粉也是很好的氮源;培养液以3%氮源、4%碳源为佳;振荡培养8d,培养液中虫草素总量是菌丝体中虫草素总量的6倍多;振荡培养7~9d,可使每瓶培养物的虫草素和腺苷总量达到10mg以上。     

低能离子束修饰蛹虫草菌株高产虫草素

虫草素具有抗肿瘤、免疫调节、抗炎等多种功效。为了更好地开发蛹虫草资源,选择合适剂量的低能离子束注入蛹虫草,优化虫草素的提取工艺条件,采用紫外分光光度法检测注入前后菌株中虫草素的含量。结果表明:最佳注入剂量为2.60×1015ions/cm2,虫草素最佳的微波-超声波提取工艺为:乙醇浓度70%,提取功率200W,提取时间110s,料液比1:240。选育出虫草素含量较高的15株菌株,最高含量达(11.924±0.063)mg/g,比原始菌株增长了近30%。     

Effects of culture conditions on the mycelial growth and bioactive metabolite production in submerged culture of Cordyceps militaris

The influence of initial pH value, various nitrogen sources, plant oils, and modes of propagation (shake-flask and static culture) on the production of biomass, exopolysaccharide (EPS), adenosine and, in particular, cordycepin, by Cordyceps militaris CCRC 32219 were investigated. Optimal conditions for mycelial growth, EPS and cordycepin production were observed at relatively low pH. Amongst organic sources, yeast extract (YE) was favorable for EPS and cordycepin production, while corn steep powder (CSP) was favorable for adenosine production. A lower C/N ratio was favorable for adenosine and cordycepin production; however, too low a C/N ratio led to diminished production. All plant oils tested stimulate mycelial growth and EPS production of C. militaris, but they did not show much effect on the adenosine and cordycepin production. A two-stage fermentation process by combining shake-flask fermentation with static culture significantly enhanced cordycepin production. A Box–Behnken experimental design was employed to optimize the production of cordycepin, which showed that the optimum conditions to produce cordycepin by C. militaris CCRC 32219 were at pH 6, YE concentration of 45 g/l and 8.0 day of the shake culture followed by 16 days of the static culture. Under the optimized conditions, the maximum production (2214.5 mg/l) of cordycepin was obtained, which is much higher than those reported up to date.     

Green synthesis approach: extraction of chitosan from fungus mycelia

Chitosan, copolymer of glucosamine and N-acetyl glucosamine is mainly derived from chitin, which is present in cell walls of crustaceans and some other microorganisms, such as fungi. Chitosan is emerging as an important biopolymer having a broad range of applications in different fields. On a commercial scale, chitosan is mainly obtained from crustacean shells rather than from the fungal sources. The methods used for extraction of chitosan are laden with many disadvantages. Alternative options of producing chitosan from fungal biomass exist, in fact with superior physico-chemical properties. Researchers around the globe are attempting to commercialize chitosan production and extraction from fungal sources. Chitosan extracted from fungal sources has the potential to completely replace crustacean-derived chitosan. In this context, the present review discusses the potential of fungal biomass resulting from various biotechnological industries or grown on negative/low cost agricultural and industrial wastes and their by-products as an inexpensive source of chitosan. Biologically derived fungal chitosan offers promising advantages over the chitosan obtained from crustacean shells with respect to different physico-chemical attributes. The different aspects of fungal chitosan extraction methods and various parameters having an effect on the yield of chitosan are discussed in detail. This review also deals with essential attributes of chitosan for high value-added applications in different fields.