Breeding Of Nosiheptide Producting Streptomyces Actuosus And Improvement Of The Dissolved Oxygen Uptake In Fermentation

In order to obtain the industrial nosiheptide producting strains, gonome shuffling was utilized to screen out the high-producting Streptomyces actuosus, and introduction of Vitrescilla hemoglobin gene into Streptomyces actuosus by genetic engineering technologies promoted the dissolved oxygen uptake in fermentation industry in this paper.In the experiment of genome shuffling we chose the rifamycin and DL-ethionine to screen out the high-producting resistance strains at first. Then the conditions of the protoplasts preparation, regeneration, inactivation and fusion of Streptomyces actuosus were optimized. After protoplasts fusions of optimal resistance strains two times we obtained the optimal strain which titer was increased by 200% than the original strain. Therefore, genome shuffling is a good method to accelerate the process of strain breeding.The plasmid containing Vitrescilla hemoglobin gene was introduced into Streptomyces actuosus through conjugal transfer, which was integrated into the chromosome of Streptomyces actuosus by the attP attachment site and expressed constructively Vitrescilla hemoglobin gene by the constructive strong promoter PmerR. PCR analysis indicated vgb had been integrated into the chromosome of Streptomyces actuosus, and CO binding difference spectrum revealed that vgb had been expressed successfully in Streptomyces actuosus, and the fermentation results showed that expression of vgb could dramatically promote the dissolved oxygen uptake in the lower level of dissolved oxygen and promote biosynthesis of nosiheptide. At the same time the recombinant strains were stable and suitable for industrial application.