Expression of Bacterial Hemoglobin in Streptomyces to Enhance Antibiotic Production

氧气限制是利用需氧菌链霉菌进行抗生素发酵的主要障碍。目前增加氧向链霉菌转移的方法包括改进的生物反应器设计和改进的培养液。解决氧气转移问题的一种新方法是开发能够更有效地从介质中获得氧气的菌株。目前的提议是针对一种表达细菌血红蛋白样蛋白的转基因菌株的开发。这种蛋白质最初是在需氧细菌透明颤菌中发现的，显然能够使细胞在缺氧环境中生存。当透明颤菌血红蛋白在大肠杆菌中表达时，重组细胞表现出更高的生长和呼吸速率，并生长到更高的细胞密度。编码这种蛋白质的基因将被导入天蓝色链霉菌，该链霉菌生产抗生素放线菌素。然后将对重组细胞的生长和呼吸特性以及放线菌素的生产进行测试。在这个系统中增强生长、呼吸和/或放线菌素产量的证明不仅对抗生素发酵，而且对任何涉及好氧细胞培养的生物过程系统都有广泛的影响。

Oxygen limitation is a major obstacle in antibiotic fermentations that utilize the aerobic bacteria Streptomyces. Current methods to increase oxygen transfer to Streptomyces include improved bioreactor design and modified culture media. A novel approach to the problem of oxygen transfer is the development of strains that can obtain oxygen from the medium more efficiently. The current proposal is directed towards the development of a genetically modified strain that expresses a bacterial hemoglobin-like protein. This protein was originally discovered in the aerobic bacteria Vitreoscilla, and apparently enables the cells to survive in a oxygen-poor environment. When Vitreoscilla hemoglobin was expressed in the bacteria Escherichia coli, the recombinant cells demonstrated higher growth and respiration rates, and grew to higher cell densities. The gene encoding this protein will be introduced into Streptomyces coelicolor, which produces the antibiotic actinorhodin. The recombinant cells will then be tested for their growth and respiratory properties, and actinorhodin production. The demonstration of enhanced growth, respiration, and/or actinorhodin yields in this system will have broad implications not only for antibiotic fermentations but for any bioprocess system that involves aerobic cell culture.