木榄内生真菌菌株ZD6及其代谢产物的抑菌活性

根据形态学特征和ITS序列分析结果,将一株从木榄茎中分离到的内生真菌菌株ZD6鉴定为桔青霉Penicillium citrinum Thom.,该菌株在优化后的发酵培养基(1%麦芽糖,2%甘露醇,1%谷氨酸钠,0.5%蛋白胨,0.15%酵母膏,200g/L土豆汁,pH6.5)中28℃、160r/min振荡培养7d后的发酵液具有明显的抑菌活性。利用柱层析及重结晶等方法从该发酵液的乙酸乙酯和正丁醇提取物中分离得到4个化合物:大黄素、环(丙氨酸-甘氨酸)、赤藓醇和甘露醇,其中的大黄素和赤藓醇为首次在桔青霉中发现,它们对枯草芽孢杆菌Bacillus subtilis的生长具有明显的抑制作用,最低抑菌浓度(MIC)分别为25μg/mL和50μg/mL;大黄素对绿脓杆菌Pseudomonas aeruginosa的生长也具有一定的抑制作用,MIC为100μg/mL。

The endophytic fungus strain ZD6 isolated from the stem of Bruguiera gymnorrhiza and the antibacterial activity of its metabolites

The endophytic fungus strain ZD6 isolated from the stem of Bruguiera gymnorrhiza was identified as Penicillium citrinum by its morphological characters and internal transcribed spacer (ITS) sequence. This strain can secrete antibacterial metabolites when cultured in modified medium (consisted of 1% maltose, 2% mannitol, 1% sodium glutamate, 0.5% peptone, 0.15% yeast extract, 200g/L potato extract, pH6.5) under the condition of 160r/min at 28℃ for 7 days in a rotary shaker. Four compounds were isolated from the ethyl acetate and n-butanol extraction of its fermentation broth. These compounds were elucidated as emodin, cyclo-(Ala-Gly), erythritol and mannitol by MS, 1H-NMR, 13C-NMR and physiochemical parameters, among which emodin and erythritol were first reported from Penicillium citrinum. Emodin and erythritol showed stronger inhibition to the growth of Bacillus subtilis with minimum inhibitory concentration (MIC) value of 25μg/mL and 50μg/mL respectively, while emodin showed moderate inhibition to the growth of Pseudomonas aeruginosa with MIC value of 100μg/mL.