ABSTRACT
Under the shaking-flask culture, fermentation medium of honggumycin produced by Streptomyces 702 were studied.The experiment was used response surface methodology to optimize the shaking-flask fermentation medium.Firstly, we applied full factorial design to screen important factors soybean meal and industrial peptone which affected hongmycin produced by Streptomyces 702.Furthermore, we designed experiment to obtain the steepest ascent path and optimal level by the central composite design.The optimum medium consisted of (g/L): maize starch 20, maize meal 20, glucose 20, soybean meal 23, industrial peptone 9, KNO_ 3 2.5, (NH_ 4 )_ 2 SO_ 4 2.5 KH_ 2 PO_ 4 0.3, NaCl 3, CaCO_ 3 6, bean oil 5mL/L.Under the optimal medium, the yield of honggumycin was up to 1500 g/mL, which was increased by 308% than the original medium.
ABSTRACT
The biochemical mechanism of degrading keratins by S.fradiae var S-221 was primarily studied.The compounds (Na_ 2 SO_ 4 , Na_ 2 SO_ 3 and sulfdryl acohol), which respecitively enhance specific activity of keratinase, activate keratinase intensively and mainly act on the disulfide bonds reductase in the keratinase, Na_ 2 SO_ 3 activates intensively both disulfide bonds reductase and polypeptide hydrolytase at 0.01 mol/L, whereas Na_ 2 S_ 2 O_ 3 , which acts on the disulfide bonds reductase, inhibits keratinase.On the condition that substrate, keratins exists, S.fradiae var S-221 is induced to produce exo-keratinase, which is a multiproteinase, containing disulfide bonds reductase, which is a key enzyme degrading keratins, then, with polypeptidic, hydrolytase, graduately hydrolyzates denatured keratins into polypeptides, oligopeptides and free amino acids, so that keratins have been decomposed completely.Sulfur in the keratins was transferred into sulfhydryl compounds, H_ 2 S and sulfates in the course of keratinolysine.
ABSTRACT
After testing the resistance of Streptomycin to the strain NS-41-80 which is the Meilingmycin producer- Streptomyces nanchangensis , a lot of streptomycin-resistant ( str ) mutants were screened after the spores regenerated on the lethal media when they were treated with 4 different dosage of super-mutagent EMS. We have abtained the high-yield strain 80-5. 11-221 from these str mutants which only produces Meilingmycin and no Nanchangmycin in the rotation-flask experiments. The productivity of 80-5. 11-221 is 1521?g/mL 77. 9% higher than CK's 855?g/mL. After the shake flask fermentation experiment of 80-5. 11-221 for six generations, the productivity of F 2 and F 3 is stable and the productivity of F 4?F 5?F 6 decreases hastily with the increment of generations. It was showed that the chemical-resistance mutation of the strains had closely relation with yield mutation and the EMS dosage of the yield mutation was higher than the resistance-chemical mutation's through the statistical analysis between the dosage of mutation and the chemical-resistance mutational frequency?the variate capacity of the mutants' yield. A model of the resistance-chemical mutational labelling rational selection of the strain producing Meilingmycin was established.