厌氧水解的新解读：快速水解和慢速水解

挥发性脂肪酸（VFA）具有可生化性好、附加价值高等优点而得到广泛应用,厌氧消化产VFA是目前学术界的研究热点,但对有机物经过水解后的生物降解性能则少有论及,厌氧发酵过程中的水解产物存在“数量”和“质量”之间的权衡问题。为了进一步提高厌氧发酵过程中微生物对有机物的利用效率,突破水解对厌氧消化的限制性作用,从基质碳源释放快慢及厌氧发酵过程中碳源降解性能不同,本文将厌氧水解分为快速水解和慢速水解,分别阐述了两种水解方式的含义、分类以及优缺点,指出细胞内外碳源的释放速率和释放方式的不同是影响厌氧产酸和生物降解性能的决定性因素。最后指出快速水解与慢速水解相结合的分阶段联合处理方式,是今后厌氧消化产VFA的主要研究方向。     

发酵法生产医药用透明质酸

山东临朐华元生物工程有限公司通过对菌株的筛选培育、发酵原料配方和工艺的改进、提纯工艺和设备的优化、制粉工艺和设备的改进、生产环境的改造,利用生物工程技术发酵法研制生产出医药用透明质酸,并形成1.5t/a的生产规模。产品应用于眼科手术、滴眼液、手术防粘连等方面,改变了国内医药用透明质酸依赖进口或动物器官提取法微量生产自用的局面,为国内以透明质酸为基质的制剂产品发展打下了基础。     

添加表面活性剂促进兽疫链球菌高产透明质酸

研究了不同类型表面活性剂对兽疫链球菌Streptococcus zooepidemicus H24菌体生长和透明质酸发酵的影响,在此基础上,进一步研究了2.5 L发酵罐中阳离子型表面活性剂十六烷基三甲基溴化铵（CTAB）的添加对透明质酸发酵的影响。研究结果表明：摇瓶发酵时,发酵中后期（12 h）添加离子型表面活性剂有利于透明质酸产量的提高,在摇瓶中添加20 mg/L阳离子型表面活性剂CTAB使HA比对照组提高20%;发酵罐上8～12 h流加CTAB可使兽疫链球菌细胞荚膜脱落,促使透明质酸的产量由5.1 g/L提高到5.7 g/L,增加11.8%。本研究结果为进一步提高发酵法生产其他黏多糖的产量提供了一定的借鉴。     

CHARACTERISTICS OF SEQUENTIAL SOLVENT PRE-EXTRACTION IN THE ISOLATION OF HUMIC ACID FROM THE ALGA PILAYELLA LIT TOR A LIS

Plants are newly discovered sources of important biopolymers called humic acids (HA). Purified HA isolation from plants and other sources begins with sequential Soxhlet extraction with diethylether, acetone, ethanol and dioxane. We have investigated the characteristics of these steps in the isolation of HA from the brown alga Pilayella littoralis. The mass balance of the total HA isolation procedure and the lime dependences of each step are reported. Experimental extraction variables included the solvent cycle time, temperature, age since harvesting of the Pilayella source material and the length to diameter ratio of the source extracted. Non-humic constituent extraction from Pilayella does not depend on solvent diffusion in or out of the source matrix. Extraction rates are determined by rapid, non-ideal equilibria or zero order kinetic processes, depending on the solvent, the duration of extraction and the age of the Pilayella sample. The equilibria and kinetically controlled steps have small temperature dependences. The data will assist HA isolation from other sources. Since non-humic substances are removed, we endorse reflux solvent Soxhlet pre-extraction in the isolation of purified HA from plants and other sources.     

Comparisons of existing pretreatment,saccharification, and fermentation processes for butanol production from agricultural residues

Some of the most recent, relevant, industrial and academic contributions made in the field of butanol production are reviewed here. The focus on butanol is due to the growing demand for non‐fossil biofuels. In addition, butanol can be mixed with fossil fuels or can be used alone, allowing an alternative to gasoline. Butanol can be synthesised biologically using sugars extracted from biomass such as agricultural waste. This agricultural waste must be pretreated before it is suitable for sugar extraction. Following this stage, enzymatic hydrolysis is employed, before performing fermentation using microorganisms. This article summarises some of the economical methods such as simultaneous saccharification and fermentation (SSF). Different pretreatment and saccharification processes were compared. Acid pretreatment and saccharification achieved the highest sugar concentrations from wheat straw. Monoethanolamine pretreatment achieved highest sugars from hardwood. Comparisons and analysis of different types of fermentation processes illustrated that immobilised reactor provided the best butanol rate of production. Integration of fermentation with product removal process improved butanol production in immobilised reactor. Gas stripping method was illustrated to be the product removal process. © 2011 Canadian Society for Chemical Engineering     

γ-聚谷氨酸的提取方法改进

目的:通过实验研究获得一种生产成本较低、生产工艺相对简单的γ-聚谷氨酸提取方法。方法:利用枯草芽孢杆菌通过发酵生产得到含有γ-聚谷氨酸的发酵液,再以异丙醇作为沉淀剂提取发酵液中的产物。用浓盐酸对产物进行水解,水解产物用四氯对苯醌进行衍生后利用高效液相色谱法测定产物的纯度和产量。最后利用薄层色谱和红外光谱对产物进行结构鉴定。结果:利用该提取方法得到γ-聚谷氨酸的产量为17.70 g·L-1,其纯度为95%。结论:在低温下用异丙醇沉淀发酵液中的产物是提取γ-聚谷氨酸的一种有效可行的方法。     

兽疫链球菌NW-162发酵产生的透明质酸分离纯化研究

对兽疫链球菌诱变株NW-162发酵液中透明质酸(HA)的分离提取工艺方法进行了对比研究。采用乙醇沉淀分离透明质酸、链霉蛋白酶酶解结合氯仿除去蛋白质及经氯代十六烷吡啶分级分离工艺,结果表明:乙醇与上清液的体积比为2.5∶1.0时沉淀透明质酸25 h最为经济;酶解结合氯仿去除蛋白质较氯仿单独作用时,透明质酸产量及纯度均有一定提高,再经氯代十六烷吡啶分级分离后,可得纯度为71.5%、蛋白质质量分数2.8%、产量0.747 g/L、相对分子质量725×103的透明质酸产品。     

Properties of gas detonation ceramic coatings and their effect on the osseointegration of titanium implants for bone defect replacement

An optimal performance of bone implants with bioceramic coatings is closely related to the surface modification technology. For the first time, we have evaluated a gas detonation deposition (GDD) approach to obtain biocompatible ceramic coatings based on bioglass (BG) and calcium phosphates on Ti-based alloys as prospective materials towards their application for the development of bone implants. For the production of the coatings, hydroxyapatite (HA), HA metal-substituted (containing Ag⁺, Cu²⁺, or Zn²⁺) and tricalcium phosphate (TCP) were synthesized and characterized. Pure powders and their combination with BG were used to obtain coatings on a Ti–6Al–4V alloy using the developed automatized GDD setup. The microstructure, phase and chemical composition of the produced coatings were studied using XRD, SEM-EDS and Raman spectroscopy. The produced coated materials were evaluated in vivo in Wistar rats to analyze a reparative osteogenesis over a period of 12 weeks. The results regarding the optimization of the GDD method indicate its high productivity, as confirmed by high deposition rates. The highest deposition rate was observed for the coatings obtained from the HA metal-substituted powders. The results revealed a partial transformation of a HA phase to an α-TCP phase during the deposition, with a prevalence of the HA-phase in the coatings. According to the histological evaluation, the reparative osteogenesis occurs through the perimeter of the titanium implants, whereas the regeneration level increases from the 4th to the 12th week. The highest osteointegration level was detected for the implants coated with a biocomposite consisting of BG, HA and TCP. The results of the current study demonstrate an effectiveness of the GDD method to produce biocompatible coatings on Ti-based alloys. This provides excellent prerequisites towards the application and standardization of the GDD technology to manufacture bone implants for bone fixation and defect replacement, as well as the development of dental implants.     

利用废弃碳资源生产鼠李糖脂的研究进展

鼠李糖脂是微生物合成的一类糖脂类生物表面活性剂,具有优异的表面活性、理化性质和广阔的应用前景。铜绿假单胞菌是鼠李糖脂生产的主要发酵菌株,能够以多种水溶性碳源或疏水性碳源为底物发酵生产鼠李糖脂。当前,废弃碳资源导致的浪费和污染问题日益严峻,基于鼠李糖脂的特性与生产菌株的底物偏好性,以废弃碳资源为原料生产鼠李糖脂具有很大的发展潜力。本文分别介绍以废油脂(含油废水、食品加工废油和餐厨废油)、含糖废弃物(含糖的食品加工副产物、含糖果蔬废弃物和木质纤维)和废塑料等高聚废弃物为原料合成鼠李糖脂的研究进展,重点总结了不同底物和生产菌株对鼠李糖脂生产的影响。通过分析废弃碳资源当前利用现状,发现繁多的种类、较低的分类程度和难降解的组分是限制以废弃碳资源作为底物生产鼠李糖脂进一步发展的主要因素,并提出以废弃碳资源生产鼠李糖脂的未来发展方向。     

透明质酸的产需情况及市场分析

介绍了透明质酸的性能、生产方法、用途和市场情况。透明质酸(HA)是近年来较为热点的生化产品之一,由于具有优良的保湿、润滑和生物相容性能,被应用于日化、医药、保健食品等领域。目前,全球透明质酸的年生产能力达到20t/a,2006年国内发酵法透明质酸的生产厂家达到8家,年生产能力约8t/a,大约40%的产品出口美国、日本等地。     

生物基有机酸提取分离技术研究进展

有机酸如乳酸、琥珀酸、柠檬酸、衣康酸、苹果酸等在工业上有重要应用,随着食品、医药、化学合成等工业的发展,有机酸需求骤增,发酵生产有机酸逐渐成为生物工程领域中一个重要而成熟的分支,但存在产物浓度低、成分复杂、后处理量大等问题. 有机酸亲水性好、不同有机酸物理化学性质相近等特点导致产物分离提纯困难,成为制约生物法生产有机酸的瓶颈. 分离发酵液中有机酸的方法主要有沉淀法、萃取法、吸附法、离子交换法、膜分离法、电渗析法和酯化法等. 通过各种分离方法的对比,发现单一的分离方法很难有效分离有机酸. 集成不同分离方法,可简化分离工艺,分离效果更好. 此外,采用新型分离耦合技术,可实现有机酸的连续或半连续生产,是未来发酵行业的一个重要发展方向.     

α-淀粉酶的研究与应用进展

α-淀粉酶是一种重要的淀粉水解酶,它能够切断淀粉内部的糖苷键,产生糊精、低聚糖和葡萄糖等。α-淀粉酶可以从植物、动物或微生物中获得,但工业应用中的α-淀粉酶绝大多数来自细菌和真菌。不同来源的淀粉酶活力和热稳定性有很大差异,其中嗜热淀粉酶在实际应用中非常重要和广泛。α-淀粉酶的制备工艺可以采用深层发酵或固态发酵的方法。目前α-淀粉酶已广泛应用于食品、纺织、造纸、洗涤剂工业,用于生产麦芽糊精,淀粉改性,葡萄糖、果糖的制备,燃料乙醇的生产等等。主要阐释α-淀粉酶的性质、制备、纯化、表征以及在工业中的应用。     

菌丝球形态的黑曲霉发酵液浸出铜尾砂

尾砂中含有大量的金属,是一种潜在的可利用资源。旨在研发一种从铜尾砂中回收铜的生物浸出方法。利用正交设计,通过摇瓶试验,研究培养温度、发酵时间、接种量及培养基成分对黑曲霉菌丝球形态的影响,进而研究不同菌丝球形态的黑曲霉发酵液对尾砂中铜的浸出。研究表明,铜的浸出率随着黑曲霉菌丝球直径的减小而升高。在温度30℃,接种量0.8%(OD₆₀₀=0.1),马铃薯-蔗糖含量30%,发酵时间65 h的优化发酵条件下,获得大量表面光滑、直径为0.96 mm的菌丝球;利用该条件下的发酵液,在30℃,180 r·min^-1条件下浸出3 d,铜的浸出率达83.25%。     

红茶菌制备细菌纤维素的研究

寻找高效的生产菌和发酵工艺以及廉价高效的培养基是解决当前细菌纤维素产业化面临的高生产成本和低产率等瓶颈问题的重要手段。以红茶菌和木葡糖酸醋杆菌作为生产菌株,比较研究了不同碳源、氮源以及茶叶浓度对两种菌合成细菌纤维素的影响。结果表明,以红茶菌制备的细菌纤维素与木葡糖酸醋杆菌无本质区别;红茶菌生产细菌纤维素的效率显著高于木葡糖酸醋杆菌,产量可提高3倍以上。     

微生物好氧发酵法生产甘油

生物好氧工业化生产甘油的工艺过程包括酶法葡萄糖液制备、种子制备、发酵和提取精制4个工 段,采用的载体蒸馏技术克服了甘油真空蒸馏得率低、残渣清除困难两大难题。该专题建立了年产1000t的发酵 甘油装置,并生产出食品级和医药级高品质甘油。     

发酵甘油的制备,提取与纯化

对甘油的发酵生产及其后处理提取与纯化进行了综述,并对我国现行的甘油发酵生产状况进行了分析与探讨。     

发酵透明质酸蛋白脱除方法的比较研究

以发酵的透明质酸(HA)粗品为纯化对象,以改良的咔唑法和考马斯亮蓝法为检测手段,比较了Sevage法、固定化蛋白酶-Sevage法、Sevage-CPC法、冻融-Sevage法脱除HA粗品中蛋白的效果.研究了有机相比例、振摇时间、HA粗品浓度对Sevage法脱除蛋白的影响,结果表明,Sevage法脱除蛋白的最优条件为:HA粗品浓度10 g·L-1、正丁醇和三氯甲烷的体积比1:4、振摇时间30 min.通过比较,发现Sevage法HA损失率低但蛋白脱除效果差;固定化蛋白酶-Sevage法蛋白脱除效果好,操作简便,适于工业化;冻融-Sevage法操作简单,蛋白脱除效果好,但成本高,适于小批量生产;Sevage-CPC法可得到最纯的HA,但成本高、工艺繁琐, CPC不能回收,有待于进一步的研究.     

叔胺萃取分离钴(II)、铁(II)

研究了不必预先氧化二价铁,直接用叔胺从氯化物溶液中萃取分离钴(II)、铁(II)的新方法. 考察了不同改性剂对叔胺萃取钴(II)、铁(II)的影响以及各种因素对钴(II)、铁(II)萃取、洗涤及反萃的影响. 提出了用叔胺萃取分离钴(II)、铁(II)的最佳工艺参数.     

固定化酵母乙醇萃取发酵研究

以十二烷醇为萃取剂，对固定化酵母乙醇萃取发酵进行了研究。探讨了萃取剂对酵母细胞的毒性，以及萃取剂用量、搅拌转速、基质浓度等因素与乙醇萃取发酵的关系，并测定了萃取过程中乙醇的分配系数。为固定化酵母乙醇发酵与溶剂萃取耦合新工艺的开发研究提供了资料。     

Production of polyhydroxyalkanoates: the future green materials of choice

Polyhydroxyalkanoates (PHAs) have recently been the focus of attention as a biodegradable and biocompatible substitute for conventional non degradable plastics. The cost of large‐scale production of these polymers has inhibited its widespread use. Thus, economical, large‐scale production of PHAs is currently being studied intensively. Various bacterial strains, either wild‐type or recombinant have been utilized with a wide spectrum of utilizable carbon sources. New fermentation strategies have been developed for the efficient production of PHAs at high concentration and productivity. With the current advances, PHAs can now be produced to a concentration of 80 g L^?1 with productivities greater than 4 g PHA L^?1 h^?1. These advances will further lower the production cost of PHAs and allow this family of polymers to become a leading biodegradable polymer in the near future. This review describes the properties of PHAs, their uses, the various attempts towards the production of PHAs, focusing on the utilization of cheap substrates and the development of different fermentation strategies for the production of these polymers, an essential step forward towards their widespread use. Copyright © 2010 Society of Chemical Industry