Expression of Bacterial Hemoglobin in Streptomyces to Enhance Antibiotic Production

氧限制是利用需氧细菌链霉菌进行抗生素发酵的主要障碍。目前增加氧转移到链霉菌的方法包括改进生物反应器设计和修改培养基。一种解决氧气传递问题的新方法是开发能够更有效地从介质中获取氧气的菌株。目前的建议是针对开发一种表达细菌血红蛋白样蛋白的转基因菌株。这种蛋白质最初是在需氧细菌玻璃体振荡菌中发现的，它显然能使细胞在缺氧环境中存活。当玻璃体振荡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引入到产生抗生素放线菌素的冷色链霉菌中。然后将测试重组细胞的生长和呼吸特性，以及放线菌素的产生。该系统中提高生长、呼吸和/或放线菌素产量的论证不仅对抗生素发酵，而且对任何涉及有氧细胞培养的生物过程系统都具有广泛的意义。

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.