Enhancement production of qinlingmycin by a soilderived Streptomyces No. 24 using protoplast fusion technology and assessment of antibacterial activity

This study was aimed at improving qinlingmycin production by protoplast fusion technology for Streptomyces No. 24 and mutant strain Ms-24. In the protoplast preparation, the optimal glycine concentration, lysozyme concentration and lytic time were 0.25%, 1 mg/ml and 1 h, respectively. In the process of protoplast fusion, the weight of polyethylene glycol (PEG) molecule had little effect, while the top fusion efficiency was observed at 50% PEG. By protoplast fusion, the three high qinlingmycin producing fusants Pf77, pf126 and pf138 were fortunately obtained from 163 fusant strains. In vitro antibacterial activities of the three fusants than Streptomyces No. 24 were increased by 43.48, 60.87 and 65.22%, respectively. The results by HPLC detection analysis showed qinlingmycin productions of the fusants fermented broths were increased by 36.59, 74.39 and 91.46%, respectively, than that of Streptomyces No. 24. The fusants showed good heredity stability in continuing transferred ten generations test.Key words: Protoplast fusion, Streptomyces No. 24, mutant Ms-24, qinlingmycin, antibacterial activit