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Nectria sp.JZ6是从浙贝母新鲜鳞茎中首次分离到的一株内生真菌,其发酵液具有抑菌活性。为建立该真菌稳定分泌抑菌活性成分的发酵体系,本研究利用单因素实验和正交实验确定了发酵培养基的配方并初步优化了发酵条件。结果表明,将活化后的菌种接种于改良查氏培养基(8%葡萄糖,0.5%蛋白胨,0.05%KCl,0.1%K2HPO4,0.15%MgSO4,pH6.5)中,28℃、150r/min振荡培养6d后获得的发酵液抑菌活性比优化前提高了26%。该发酵液经100℃水浴30min不失活,在pH1-5时抑菌活性相对稳定,其后逐渐减弱,并在pH9.0及以上时丧失。Nectriasp.JZ6发酵液的乙酸乙酯浸膏抑菌活性最强,对金黄色葡萄球菌、藤黄八叠球菌、枯草芽孢杆菌、绿脓杆菌和大肠杆菌的最低抑菌浓度(MIC)分别为0.625、0.625、1.25、1.25和1.25mg/mL。
Nectria sp.JZ6 is an endophytic fungus isolated from the fresh bulb of Fritillaria cirrhosa for the first time, and its fermentation broth has antibacterial activity. In order to establish a stable fermentation system for the fungi to inhibit the secretion of antibacterial active ingredients, single factor experiments and orthogonal experiments were used to determine the fermentation medium and optimize the fermentation conditions. The results showed that the activated strain was inoculated into modified Charpy medium (8% glucose, 0.5% peptone, 0.05% KCl, 0.1% K2HPO4, 0.15% MgSO4, pH6.5) The antibacterial activity of the fermentation broth obtained after 6 days of cultivation was increased by 26% compared with that before optimization. The fermentation broth was not inactivated by water bath at 100 ℃ for 30min, its antibacterial activity was relatively stable at pH 1-5, then gradually weakened, and was lost at pH 9.0 and above. The ethyl acetate extract of Nectriasp. JZ6 fermentation broth has the strongest antibacterial activity, and the minimum inhibitory concentration (MIC) against Staphylococcus aureus, Sarcina lutea, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli were 0.625 , 0.625, 1.25, 1.25 and 1.25 mg / mL.