Medium Optimization For Production And Extraction Of Bioactive Substance From Fermentation Broth By Streptomyces Lavendulae X33

Streptomyces lavendulae X33 is a biocontrol strain isolated from the rhizospheric soil of citrus by our laboratory.The previous study implied that it possessed a strong inhibitory activity against Penicillium digitatum and many other pathogenic fungi of citrus,so the stain had a potential to be developed as a new type of citrus post-harvest preservative.The natural screening,optimization of fermentation media,physicochemical property and extraction of active substance were carried out on Streptomyces lavendulae X33 in the paper,in order to provide a theoretical foundation for further exploitation of the strain.The results were as follows:?1?Found the relationship between colony morphology and production of bioactive substance,the results showed that the colonies with regular circle and lager sporulation quantity had the best inhibition effect on Penicillium digitatum;as well as the highest production.?2?The fermentation medium were optimized by single factor experiment,factorial experiment,steepest ascent experiment and central composite design.The optimal medium was as follows:soluble starch 52g/L,beef extracts 2.4g/L,NH₄Cl 0.625g/L,peptone form fish 16.53g/L,NaCl 14.89g/L,CaCO₃ 0.02g/L,pH7.0??3?It was showed that the bioactive substance was a kind small molecule substance which had strong polar and presented alkaline,and the substance dissolved in water easily but insolubled in the organic solvents by the thermal treatment,sevage method,dialysis experiment,paper chromatography experiment and solvent extraction experiment.?4?The bioactive substance could be extracted by D151 cation exchange resin.The process was as follows:the ration of fermentation broth and D151 cation exchange resin was 9:1,the eluting agent was 2mol/L NaCl,and its volume was 13:1 to the resin,the final washing rate reached 73.52%.Then the eluent was desalted by D101 macroporous adsorption resin and sephadex G-25,a 65 times concentrated bioactive substance solution was obtained by educed pressure condense,and its concentration was 1.44 times of the broth.The maximum absorption wavelength was 224nm by means of the full wavelength scanning.