Study On The Solid-Liquid Sepearation Process Of Streptomyces Fermentation Broth

Streptomyces bacteria is a major producer of antibiotics, such as oxytetracycline, avermectin, streptomycin. At present, the optimization of fermented liquid filtration appears to be more and more important.Because, the separation and purification of microbial medicine produced by the fermentation are facing a series of new problems, low content, easy deactivation, lower extraction yield, etc. Flocculation has become the research focus of the pretreatment of current antibiotic fermentation broth with its many advantages. In this dissertation, the optimization of flocculation process of oxytetracycline, avermectin, streptomycin fermentation broth was mainly studied, and the best conditions for flocculation were determined.In the flocculation experiments of the oxytetracycline, the effects of flocculant type, dosage, concentration and pH of fermentation broth on the filtration rate, filtrate titer and transmittance of fermentation broth has been investigated. Some reagents can significantly improve pretreatment effect, and among them, cationic polyacrylamide and chitosan combined is the most significant effect in general. The best flocculation conditions were optimized: polyacrylamide concentration for 0.1%, the dosage for 50 ppm, pH value to about 2.0. Under these conditions, the protein content in filtrate decreased, liquid crystals had a small loss of potency. And these had certain decoloring role for filtrate, therefore, using polyacrylamide processing replaced decoloring technology is very promising.The effects of flocculant type, dosage and pH of fermentation broth on floc particles, the supernatant clarity of fermentation broth has been investigated in flocculation experiments of avermectin. According to the screening process condition, flocculation can significantly improve fermented liquid filtration properties, reduce the filtrate COD, and among them, the PAC and cationic system is most significant. When the PAC dosage is 15 mg/L, cationic polyacrylamide ionization is 30%, the amount of 160 ppm, pH value 7.0,flocculation particle was the largest, relatively uniform and close-grained, and get clear liquid with high transparency. In these conditions for avermectin broth flocculation,the filtration performance of the fermentation broth was improved,and the COD content in waste reduced at the same time. These results are valuable for avermectin for practical production.The effect of ferrocyanide, zinc sulfate dosage, PAM dosage and type, ionic degree and the molecular weight, fermentation broth pH, dilution on flocculation has been investigated in flocculation experiments of streptomycin. The best flocculation conditions were optimized:ferrocyanide, zinc sulfate dosage 0.1%, cationic polyacrylamide ionization is 20%, the amount of 40 ppm, fermentation broth without adjusting pH, and its 2-fold dilution. The fermentation broth filtration rate, transmission rate have improved and the titer loss was lesser with the optimized conditions, and these have important significance for practical production.