中文摘要：

对中药植物茜草（Rubia cordifoliaL）的内生菌进行了分离和抗菌活性筛选,获得一株具有广谱抗菌活性的内生细菌。该细菌对常见的3种人类病原菌和4种植物病原菌具有拮抗作用。传统分类学和基于16S rRNA基因的分子分类学证据表明,该内生细菌为一株新的枯草芽孢杆菌,命名为Bacillus subtilisRC4。B.subtilisRC4在综合马铃薯培养基（pH值5.0）中于28℃振荡培养60h,产生的代谢物对白色念珠菌的抗菌活性最强。抗菌活性物质在100℃受热20min,活性维持80%以上,且在pH值2.0-11.0范围内稳定。经硅胶柱层析和高效液相色谱分离,得到主要抗菌活性化合物,质谱分析表明其分子量约为288Da。

英文摘要：

Rubia cordifolia were first used for endophyte isolation. Among 9 isolates an endophytic bacterium was found to possess a broad antimicrobial spectrum against hunman - pathogens and plant - pathogens. This bacterium was identified to be a new Bacillus subtilis strain based on its morphological characters and 16S rRNA sequence analysis, and was designated as B. subtilis RC4. Candida albicans was used as the indicator train for screening the antimicrobial activity. The cultures of B. subtilis RC4 exhibited the strongest activity after 60h cell growth in potato medium （pH5.0） at 28℃. The activity in superuatant was stable at a pH range from 2.0 to 11.0 and retained over 80% after 20min at 100℃. The major antimicrobial metabolic was purified from the fermentation broths through bioassay - guide fractionation of silica gel and C18 reverse chromatography. Its molecular weight was 288 Da.