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Alginate production by mutants of Azotobacter vinelandii: advanced strategies for cultivation under microaerophilic conditions and overpressure

维氏固氮菌突变体生产藻酸盐：微需氧条件和超压下培养的先进策略

基本信息

批准号：
351299388
负责人：
Professor Dr.-Ing. Jochen Büchs, since 4/2018
金额：
--
依托单位：
Instituto de Biotecnología
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2022-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/351299388?language=en
关键词：
Alginate production mutants Azotobacter vinelandii

项目摘要

Highly viscous fermentation broths are one of the problems frequently encountered in the development and scaling of bioprocesses. The production of polysaccharides can be considered as an example of such processes. In the field of microbial polysaccharides, alginates are counted among the most important ones. Alginate is a polymer composed of beta-D-mannuronic acid (M) and alpha-L-guluronic (G) acid and produced by brown algae and bacterial species such as Azotobacter vinelandii and Pseudomonas aeruginosa. Alginates have a wide scope of application due to their use as viscosifiers and gel forming agents, making them of great interest to several industrial areas. Because most details of the alginate biosynthesis are known, as well as the metabolic relationships of this pathway with other pathways present in A. vinelandii, it was possible to generate overproducing strains of this biopolymer. Moreover, genetic modifications allow to influence the physical and chemical properties of the produced alginate. In addition, previous studies have shown that for very low dissolved oxygen tensions (microaerophilic conditions), it is possible to manipulate both the molecular mass as well as the degree of acetylation of alginate produced by A. vinelandii. For this reason the highest priority of this proposal is to investigate the potential of microaerophilic conditions to significantly maximize the alginate formation with specific chemical characteristics by genetically modified strains of A. vinelandii. The formation of alginate leads to a non-Newtonian fluid behavior of the fermentation broth with a significant impact on mixing homogeneity, power input into the liquid, heat removal and in general on the reproduction of results. Thus, the scale up from shake flask to stirred tank reactor is a major challenge for this biological system. Process scale up and reproduction of results on shake flask level, lab scale stirred tank reactor as well as in a 50 L pilot scale pressure reactor will therefore also be an important part of this proposal. In addition, this project will give students and scientists the opportunity for research stays in the Mexican group of Dr. Peña at UNAM Institute of Biotechnology and the German group of Dr. Regestein at RWTH Aachen University.

高粘度发酵液是生物过程开发和规模化过程中经常遇到的问题之一。多糖的生产可以被认为是这种方法的一个例子。在微生物多糖领域，藻酸盐被认为是最重要的多糖之一。藻酸盐是由β-D-甘露糖醛酸（M）和α-L-古罗糖醛酸（G）组成的聚合物，并且由褐藻和细菌物种如棕色固氮菌（Azotobacter vinelandii）和铜绿假单胞菌（Pseudomonas aeruginosa）产生。藻酸盐由于其作为增粘剂和凝胶形成剂的用途而具有广泛的应用范围，使得它们对几个工业领域具有极大的兴趣。由于藻酸盐生物合成的大多数细节是已知的，以及该途径与存在于A. vinelandii，有可能产生这种生物聚合物的过度生产菌株。此外，遗传修饰允许影响所产生的藻酸盐的物理和化学性质。此外，以前的研究表明，对于非常低的溶解氧张力（微需氧条件），可以操纵A. vinelandii。由于这个原因，本建议的最高优先级是研究微需氧条件的潜力，以显着最大化的藻酸盐形成与特定的化学特性的遗传修饰菌株的A。vinelandii。藻酸盐的形成导致发酵液的非牛顿流体行为，对混合均匀性、输入液体的功率、热量去除以及通常对结果的再现具有显著影响。因此，从摇瓶到搅拌釜反应器的规模扩大是该生物系统的主要挑战。因此，工艺放大和摇瓶水平、实验室规模搅拌釜反应器以及50 L中试规模压力反应器的结果再现也将是本提案的重要组成部分。此外，该项目将为学生和科学家提供在墨西哥国立自治大学生物技术研究所Peña博士小组和亚琛工业大学Regestein博士德国小组进行研究的机会。