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.