多形汉逊酵母启动子的挖掘

多形汉逊酵母可以利用甲醇作为唯一的碳源和能量来源,是构建微生物细胞工厂的潜在宿主,在代谢工程改造和重组蛋白生产中引起了广泛关注.在合成生物学研究和代谢工程改造过程中,通常需要改变相关基因的转录水平来调节代谢通量,而这一过程需要借助不同种类、不同表达强度的启动子来实现.因此,对汉逊酵母糖酵解途径和活性氧(ROS)防御途径...     

非传统酵母代谢工程研究进展

近30年来解脂耶氏酵母、克鲁维酵母、毕赤酵母、假丝酵母、汉逊酵母等非传统酵母因其具有天然的生理代谢优势,如快速生长、多底物利用、胁迫耐受性等,在代谢工程领域得到了广泛关注,多种基因工程改造工具正逐渐被开发用于非传统酵母的特性拓展,使其成为合成重组蛋白、生物可再生化学物质的高效细胞工厂。文中总结了非传统酵母中基因编辑工具的发展,并从代谢工程改造策略角度概括了利用非传统酵母进行产品合成的研究进展。最后,讨论了非传统酵母在产品生产应用方面遇到的挑战和未来的研究方向。     

形态工程在生物基化学品生产中的应用进展

合成生物学和代谢工程是构建微生物细胞工厂、实现化学品绿色生物制造的重要方法,目前主要集中在微生物代谢网络的改造及调控上,很少考虑到微生物细胞特性的影响。形态工程通过改造微生物细胞形态相关蛋白,有目的地对微生物细胞形态及分裂方式进行合理调控,从而优化微生物细胞的特性,是降低生物炼制成本的一种新兴生物工程技术。文中首先介绍了与微生物细胞形态相关的各类蛋白,并重点总结了形态工程在生物基化学品合成方面的应用进展,包括调控细胞体积以提高胞内产物积累量、改善细胞通透性以促进胞外产物分泌、实现高密度发酵以降低生产成本、控制产物水解程度以提高产品性能。最后,提出了形态工程面临的主要问题并展望了其未来的发展趋势。     

甲醇生物转化合成化学品的研究进展

甲醇来源丰富、价格低廉,已成为生物制造行业极具吸引力的底物之一。构建微生物细胞工厂实现甲醇到增值化学品的生物转化,具有过程绿色、条件温和、产品体系多样等优势,不仅能拓展基于甲醇的产品链,还能缓解当前生物制造“与民争粮、与粮争地”的问题,是实现绿色生物制造的重要手段。因此,阐明不同天然甲基营养菌中涉及甲醇氧化、甲醛同化和异化途径对于后续基因工程改造工作至关重要,也更有利于构建新型非天然甲基营养菌。本文讨论了甲基营养菌中甲醇代谢途径的研究现状,并结合近年来天然和人工合成甲基营养菌在甲醇生物转化中的应用进展及面临的挑战。     

琥珀酸的生物制造:细菌还是酵母?

琥珀酸又称丁二酸,是一种重要的有机合成中间体。许多微生物都可以通过优化和代谢工程改造产生琥珀酸。文章对细菌和酵母两种主要的产琥珀酸类群产琥珀酸的产量、产率及后提取等因素进行了详细的分析,并比较了两种微生物生产琥珀酸各自的优缺点,为今后开发利用琥珀酸的生物制造提供参考。     

酵母生物多样性开发及工业应用

酵母是一类包括酿酒酵母和非常规酵母在内的多种单细胞真菌的总称,其中酿酒酵母是应用较多的重要工业微生物,广泛应用于生物医药、食品、轻工和生物燃料生产等不同生物制造领域。近年来,研究者从不同生态环境中分离了大量的酵母菌株,鉴定了多个新种,也发现了抗逆性不同以及具有多种活性产物合成能力的菌株,证明天然酵母资源具有丰富的生物多样性和功能多样性。利用基因组挖掘以及转录组、蛋白组等多组学分析研究,可进一步开发利用酵母遗传多样性,获得酶和调节蛋白的基因以及启动子等遗传元件改造酵母菌株。除了利用酵母的天然遗传多样性,还可通过诱变、驯化、代谢工程改造及合成生物学等技术产生具有多种非天然多样性的菌株。此外,对天然遗传元件也可以进行突变和定向进化,所产生的新遗传元件可用于有效提升菌株的性能。开发利用酵母的生物多样性,对构建高效酵母细胞工厂,生产生物酶、疫苗以及多种活性天然产物等产品具有重要意义。文中对酵母生物多样性的研究现状进行综述,并对未来高效开发利用酵母菌株资源和遗传资源的研究进行了展望。文中所总结的研究方法和思路也可为研究其他工业微生物的多样性及进行高效菌株的选育提供参考。     

代谢工程改造解脂耶氏酵母合成植物萜类化合物的研究进展

萜类化合物是一类广泛存在于植物中的天然产物,其在食品、药品和化工等多个领域中均有广泛的用途,市场潜力巨大。因此,开发生产萜类化合物等植物天然产物可再生的微生物资源来补充甚至代替原有稀少和珍贵的植物资源,具有重要的理论意义和潜在的应用价值。解脂耶氏酵母是目前使用最广泛的非常规酵母底盘细胞之一。近年来,利用代谢工程及合成生物学技术在解脂耶氏酵母底盘细胞中重构与优化萜类化合物的合成途径以实现目标代谢产物的高效合成,已经成为一项研究热点。本文系统总结了有关利用解脂耶氏酵母作为底盘细胞异源生产植物萜类化合物的具体实例和最新进展,包括所涉及的宿主菌株、关键酶、代谢途径及改造策略等,并在最后对该领域的未来发展方向进行了展望。     

生物丁醇代谢工程的研究进展

丁醇作为一种重要的大宗化学品具有广泛的用途,同时又是一种潜在的生物燃料。随着能源与环境危机的日益加重,利用可再生原料通过微生物法生产丁醇受到全世界的普遍关注。代谢工程为定向改造微生物生产丁醇提供了有力的工具。通过改造经典的丙酮丁醇发酵和定向改造模式微生物生产丁醇是生物丁醇研究的两个重要方向。笔者从代谢工程改造的角度评述近5年来生物丁醇研究的进展,同时讨论了生物丁醇研究中需要着力解决的问题。     

基于细胞亚群调控提升生物合成效率的研究进展

采用合成生物学与代谢工程技术设计与构建微生物细胞工厂是实现化学品绿色生物制造的重要方法。微生物发酵过程中低产细胞亚群和非生产细胞亚群由于代谢负担轻,更加具有生长优势,会降低产物合成的综合效率。目前,基于响应产物浓度的生物传感器,偶联产物合成与生长的细胞亚群调控系统有助于解决这个问题。综述了细胞亚群调控系统设计和构建的常用方法,重点讨论了目前细胞亚群调控系统存在的问题及其解决策略。     

生物元件的挖掘、改造与标准化

生物元件是合成生物学中的三大基本要素之一,是合成生物学的基石。现阶段,生物元件的挖掘、鉴定和改造仍然是合成生物学领域的重要研究方向之一。合成生物学与基因工程和代谢工程最显著的差别在于能够将大量的生物元件进行快速、随意的组装,而实现这一目标的前提是将生物元件标准化。目前,已经有大量基因组被解析,通过这些基因组数据库的注释与功能验证,并借助于各种生物信息学软件预测启动子、终止子、操纵了、转录因子和转录因子结合位点、核糖体结合位点以及蛋白质编码区等部件,为合成生物学提供丰富的生物元件信息资源。随着元基因组技术的兴起,大量未培养微生物中的基因和基因簇信息被解析,使得我们可以从占自然界中实际存在微生物总数99％的未知微生物中挖掘更多的生物元件。另外,生物元件可以从自然界分离出来,也可以对天然生物元件进行修饰、重组和改造后得到新的元件。酵母是异源蛋白表达的通用宿主和生物基产品生产的细胞工厂,但其本身可用的启动子非常有限,近年来各国学者在酵母启动子改造和文库构建方面做了很多工作,该文也将概述酵母启动子改造和在合成生物生物学研究领域中的应用方面的研究进展。     

Engineering of non-conventional yeasts for efficient synthesis of macromolecules: the methylotrophic genera

Methylotrophic yeasts, named after their ability to grow on methanol as the sole carbon source, have raised large interest as recombinant protein factories. In this review, we explain the basic mechanisms underlying this interest and describe the minimal requirements to transform the two genera recognized as methylotrophic, Pichia and Candida, into a powerful protein production tool. We present a comparison between this group of yeasts and the conventional yeasts used as expression system in view of productivity, level of secretion and quality of post-translational modifications. Selected examples of recombinant protein produced by methylotrophic yeast are also included.     

Emerging applications of the methylotrophic yeasts

The use of methylotrophic yeasts for the production of single-cell-protein (SCP), alcohol oxidase and fine chemicals has been proposed. Fermentation technology developed for the growth of these yeasts on methanol at high cell densities has been commercialized. However, it is the production of heterologous recombinant proteins by Pichia pastoris that is emerging as the most significant application of the methylotrophic yeasts.     

Emerging applications of the methylotrophic yeasts

Abstract The use of methylotrophic yeasts for the production of single-cell-protein (SCP), alcohol oxidase and fine chemicals has been proposed. Fermentation technology developed for the growth of these yeasts on methanol at high cell densities has been commercialized. However, it is the production of heterologous recombinant proteins by Pichia pastoris that is emerging as the most significant application of the methylotrophic yeasts.     

毕赤酵母中海藻糖的积累

毕赤酵母是甲基营养型酵母属中较常见的酵母,可用甲醇作为唯一碳源,进行蛋白质的表达.在发酵过程中菌体内含有少量的海藻糖,在40℃高温下,海藻糖的含量与30℃下比较,可提高20%以上.该数据为毕赤酵母表达后再利用提供了一定的依据.     

Heterologous protein production in methylotrophic yeasts

The facultative methylotrophic yeasts Candida boidinii, Pichia methanolica, Pichia pastoris and Hansenula polymorpha have been developed as systems for heterologous gene expression. They are based on strong and regulatable promoters for expression control derived from methanol metabolism pathway genes. An increasing number of biotechnological applications attest to their status as preferred options among the various gene expression hosts. The well-established P. pastoris and H. polymorpha systems have been utilized in especially competitive and consistent industrial-scale production processes. Pharmaceuticals and technical enzymes produced in these methylotrophs have either already entered the market or are expected to do so in the near future. The article describes the present status of the methylotrophic yeasts as expression systems, focusing on applied examples of the recent past. Received: 9 May 2000 / Received revision: 20 June 2000 / Accepted: 23 June 2000     

Cellular microbiosensors for methanol and ethanol determination on the basis of pH-sensitive field transistors]

Cellular sensors for methanol and ethanol determination were developed using immobilized mutant cells of methylotrophic yeasts Hansenula polymorpha and Pichia pinus (able to extrude protons in the presence of alcohol) and pH-sensitive field effect transistors (pH-SFETs). The intact cells of yeasts were immobilized in Ca-alginate gel to obtain a biomembrane. The minimal detectable response was obtained to approximately 0.5 mM of methanol and ethanol, a linear dependence of biosensor's response on the logarithmic alcohol concentration was observed in the range from 5 to 100 mM for both types of alcohol. The prospects for application of biosensors to determine alcohols in the analytical practice are discussed.     

Methanol utilization by a strain of Aspergillus niger: influence on the synthesis and activity of pectinases

During the production of pectinases by a strain of Aspergillus niger isolated from rotten lemons, methanol was liberated into the medium due to the cleavage of the pectin molecule used as the carbon source. The methanol was subsequently consumed by the microorganism but neither the synthesis nor the activity of pectinesterase and polygalacturonase was affected. Although not studied in detail, the mechanism involved in the utilization of methanol is similar to that described for methylotrophic yeasts.     

Metabolic engineering in design of cellular elements of biosensors

An extended definition of the term "metabolic engineering" is given and main spheres of its using in fundamental studies and modern biotechnology are discussed in this article. Emphasis is made on specific using the approaches of metabolic engineering in construction of the cell elements of sensors based on the use of mutant and chemically modified cells of methylotrophic yeasts. This investigation is designed in the laboratory of Biochemical Genetics of the Division of Cell Regulatory Systems, A. V. Palladin Institute of Biochemistry. Genetic and chemical modifications have allowed to provide some directed changes in cell sensoring output toward methanol, ethanol and formaldehyde that result in enhanced selectivity and shortened time-output of the corresponding potentiometric and amperometric sensors.     

A novel alcohol oxidase/RNA-binding protein with affinity for mycovirus double-stranded RNA from the filamentous fungus Helminthosporium (Cochliobolus) victoriae: molecular and functional characterization

We have cloned and sequenced a novel alcohol oxidase (Hv-p68) from the filamentous fungus Helminthosporium (Cochliobolus) victoriae that copurifies with mycoviral double-stranded RNAs. Sequence analysis revealed that Hv-p68 belongs to the large family of FAD-dependent glucose methanol choline oxidoreductases and that it shares significant sequence identity (>67%) with the alcohol oxidases of the methylotrophic yeasts. Unlike the intronless alcohol oxidases from methylotrophic yeasts, a genomic fragment of the Hv-p68 gene was found to contain four introns. Hv-p68, purified from fungal extracts, showed only limited methanol oxidizing activity, and its expression was not induced in cultures supplemented with methanol as the sole carbon source. Northern hybridization analysis indicated that overexpression of Hv-p68 is associated with virus infection, because significantly higher Hv-p68 mRNA levels (10- to 20-fold) were detected in virus-infected isolates compared with virus-free ones. We confirmed by Northwestern blot analysis that Hv-p68 exhibits RNA binding activity and demonstrated that the RNA-binding domain is localized within the N-terminal region that contains a typical ADP-binding beta-alpha-beta fold motif. The Hv-p68 gene, or closely similar genes, was present in all species of the genus Cochliobolus but absent in the filamentous fungus, Penicillium chrysogenum, as well as in two nonmethylotrophic yeasts examined. This study represents the first reported case that a member of the FAD-dependent glucose methanol choline oxidoreductase family, Hv-p68, may function as an RNA-binding protein.