Studies On The Polyene Macrolide Antibiotic Natamycin

According to the theory of microbiology fermentation technology, the dissertation focuses on the breeding and fermentation process conditions of Natamycin, including the selection method, the physiological and biochemical characteristic experiments, the breeding and fermentation conditions of high-producing strain, the microorganism metabolism regulation and control, the identification of natamycin, the laboratory fermentation conditions and the large scale plant experiments, the inhibition spectrum and security of natamycin. By making great efforts, the large scale plant fermentation had been achieved. The vacancy on natamycin production in China had been filled up. The main research contents and results are as follows:(1) According to the international reported background on the producing strain of natamycin, comparing with the strain characteristics in Streptomyces of streptomycetaceae in actinomycetales, we establish a relatively perfect selection method for natamycin producing strain. With Streptomyces gilvosporeus as experiment mode strain, the physiological and biochemical characteristic were studied. The basic background information has been achieved. The strain S3 which we selected could produce natamycin 0. 825g/L.(2)The fermentation condition of strain S3 in shaking flask was studied. The seed medium and the culture conditions were optimized by orthogonal design experiments. Under the optimum condition, high-producing strain S3 could produce natamycin 2. 41g/L.(3) Natamycin producing strain (S3) was treated with the UV and DES, a streptomycin-resistant mutant was screened by primary screening method with streptomycin-resistant strain and compound screening method with flask culture. A mutant SG-56 of high-producing strain was obtained. The SG-56 could produce natamycin 2.97g/L.(4) The fermentation conditions in 5L fermenter were studied. Under the best fermentation condition, the fermentation experiment in 30 M~3 large scale fermenter was also performed. The fermentation data in 30 M~3 fermenter have proved the practicability of fed-batch fermentation technology. The average yield of natamycin in 30 M~3 fermenter could reach 4. 8g/L, the maximum yield of natamycin in 30 M~3 fermenter could reach 5. 4g/L.(5) With our product natamycin in 30 M! fermenter, the IR spectrunu UV spectrunu 'H NMR spectrunu i:iC NMR spectrunu Mass spectrunu X-ray crystal lographic were determined. The result shown that the quality of our product natamycin has reached the international level.(6) The antimicrobial spectrum of our product natamycin was studied. The applications of natamycin in feed were also studied. We discussed the security of natamycin in the end, the acute toxicity was performed.The innovation of this dissertation in the research field of natamycin fermentation is as follows:(1) We firstly established the natamycin producing strain breeding method and identification method in China. By this method we obtain 5 natamycin producing strains. The HPLC determination method of natamycin in fermentation liquid was established in China. The bio-determination method was also established to determinate natamycin bioassay.(2) The streptomycin resistance screening method and traditional mutant method (DES and UV light) were applied in the breeding of the polyene macrolide antibiotic natamycin strains, the streptomycin-resistant mutant was obtained, a mutant with high natamycin yield was selected by shaking flask screening. The yield of mutant was up to 2.97g/L.(3) We have initiateated the discussion of natamycin biosynthesis metabolism regulation and control way in China. The optimum fermentation technology condition has been studied. Under the best fermentation condition, the fermentation experiment in 30 M'fermenter was also performed. The fermentation data in 30 M'fermenter have proved the practicability of fed-batch fermentation technology. The average yield of natamycin in 30 M1' fermenter could reach 4. 8g/L, the maximum yield of natamycin in 30 M' fermenter could reach 5.4g/L. The total extraction rate of natamycin is 60%. The inspection certificate have been achieved in the EU and USA, a batch natamycin has exported to many countries.