中文摘要：

以往研究已确定链霉菌胞外多糖依博素的生物合成基因簇（ste），ste15和ste22分别编码葡萄糖糖基转移酶和鼠李糖糖基转移酶。现通过基因同源重组双交换，在ste15基因缺失突变株Streptomyces sp．139（ste15^-）基础上，再进行ste22基因阻断，经Southern杂交验证，得到了ste15和ste22双基因缺失突变株Streptomyces sp．139（ste15^-ste22^-），并对该菌株进行了基因互补研究。双基因缺失株产生的胞外多糖与依博素相比，葡萄糖与鼠李糖含量明显降低，分子量下降，生物活性明显变弱。基因互补株产生的胞外多糖中葡萄糖与鼠李糖含量基本恢复至依博素水平，生物活性也显著提高。因此，进一步阐明了ste15和ste22基因参与了依博素生物合成中葡萄糖和鼠李糖重复单元序列的形成过程，在依博素的生物合成中起重要作用，变株产生的依博素新衍生物体内外生物学活性正在深入研究中。

英文摘要：

The biosynthesis cluster （ste） of a novel exololysaccharide called Ebosin producing by Streptomyces had been identified previously, that ste15 and ste22 encode glucosyhransferase and rhamnosyltransferase respectively. The ste22 gene was disrupted with a double crossover via homologous recombination in the mutant strain Streptomyces sp. 139 （ste15^-）. The mutant strain Streptomyces sp. 139 （ste15^- ste22^-） was identified by Southern blot and gene complementation also performed. Compared with Ebosin, the glucose and rhamnose of EPS15-22m produced by Streptomyces sp. 139 （ste15^ ste22^-） were reduced obviously and the Mp and the antagonist activity for IL-1 R decreased. Glucose, rhamnose and the antagonist activity for IL-1R were recovered in EPS15-22c producing by the gene complemented strain. It elucidated that genes ste15 and ste22 play essential roles in the formation of repeating units of sugars during Ebosin biosynthesis. The activities of Ebosin new derivatives produced by the mutants need to be studied further both in vitro and in vivo.