Breeding Of High-yield Erythromycin Producer Saccharopolyspora Erythraea And Optimization Of Erythromycin Production Processes

Erythromycin is one of polyketide antibiotics, which is mainly produced by Saccharopolyspora erythraea in submerged culture at production scale. Nowadays, the most challenge is to improve the production titer of erythromycin. In this thesis, two parts work were conducted to enhance erythromycin production level, which include breeding and screening of high-yield S. erythraea strain and erythromycin fermentation process optimization based on on-line monitoring strategy. The results were showed as follows.Regarding breeding of S. erythraea, initially, an integrated mutation method has been established based on atmospheric and room temperature plasma (ARTP) treatment, UV irradiation and chemical hydroxylamine hydrochloride stress. The procedure was developed as follows:the free spores of S. erythraea were irradiated within 120s by ultraviolet ray at 254nm, then, treated for 30 seconds by ARTP, followed by thorough spreading on the spore formation plate with 0.007g/L hydroxylamine hydrochloride. Finally, all spores were cultivated at 34 degree in the dark room. With respect to high through-put screening of high-yield spores, it was successfully developed as well. Firstly, a 48-deep-well microplate cultivation instead of shaking flask culture was investigated for erythromycin fermentation, an easy and quick quantitative method for the titer of erythromycin was established using a microplate reader. On the basis of the high-throughput screening model and mutation method developed here,72 high-yield mutants had been screened from 1200 mutants. Erythromycin titer of DZ65 was 16.5% higher than parental strain.Regarding process optimization of erythromycin fermentation, carbohydrate feeding based on the control of OUR process optimization and utilization of electronic nose on-line monitoring and feedback control the concentration of n-propanol were investigated. Erythromycin titer was 20% higher than the control group through bringing forward carbohydrate supplement time and maintaining OUR level. Besides, it was proved that controlling OUR can improve the production of erythromycin A. The models for n-propanol detection based on the response value of electronic nose were established, and the on-line monitoring feedback system of the n-propanol concentration was applied in 50L fermenter. Results showed that maintaining n-propanol concentration at 1000±38 ppm directed by electronic nose could result in the highest erythromycin yield.