Breeding High-yield Strains Of The Spectinomycin And Fermentation Process

Spectinomycin, which was a microbial broad-spectrum antibiotic, was a secondary metabolite from the aerobic fermentation of Streptomyces spectabilis. Attributes of spectinomycin included: no hypersusceptibility, small side effects and safety. It is not only the first-select drug for treatment of gonorrhea, but also have a good effect on speeding growth of animals. So there will be a good economic and social benefits to study it. In this dissertation, strain improvement, optimization of spectinomycin fennentation process and scale-up of fermentation processes in fermentor was studied.According to the biosynthesis pathway of spectinomycin, strain improvement was performed by mutation and rational screening to improve the productivity. By mutation with mutagens such as NTG, EMS, UV and rational screening for spectinomycin-resistant mutants etc, spectinomycin over-producing strain 04-97 was obtained. The spectinomycin titer of strain 04-97 reached 3436 u/ml, which was 60% higher than that of the original strain 02-56. Subculture test indicated that the hereditary character of strain 04-97 was stable.In this dissertation, the medium composition and the fermentation conditions for spectinomycin production were investigated. The optimal medium composition, which was obtained through single factor experiments and orthogonal design experiments, was as follows (%): starch 4.0, yeast powder 1.25, soybean cake powder 0.75, soybean oil 1.0, barbital 0.06, ammonium sulfate 0.1, others are invariable. The fermentation conditions were as follows : inoculation amounts of first seed tank was 700 ml, others was 10%, liquid volume 50ml in 500 ml shaking flask, initial pH value of medium 6.0, culture temperature 33 ± 0.5 ℃ . After adopts this process, the spectinomycin titer of the optimal fermentation condition reached 4400 u/ml, which was increased by 28.8% compare to that of the original fermentation condition.Finally, based on above experimental data, test in fermentor were also carried out and the fermentation process was optimized according to the actual conditions. The fermentation kinetics of spectinomycin over-producing strain 04-97 was also studied in this dissertation. Based on test of single factor , the scale-up of spectinomycin fermentation from shaking flask to first seed tank, second seed tank and fermentor was realized successfully, and the titer of spectinomycin over-producing strain 04-97 in 42 m3 fermentor reached 3400 u/ml which was increased by 50% compare to that of the original strain 02-56.