海洋细菌中活性化合物的筛选策略

目的 从700多株海洋沉积物分离得到的细菌中筛选安莎类抗生素和6-脱氧己糖(6DOH)糖基化修饰的次级代谢产物产生菌.方法 以3-氨基-5-羟基苯甲酸(AHBA)合酶基因和dTDP-葡萄糖-4,6-脱水酶基因为靶标,分别进行安莎类抗生素和6DOH糖基化修饰的次级代谢产物产生菌的分子筛选.对AHBA合酶及dTDP-葡萄糖-4,6-脱水酶基因阳性的菌株发酵液及提取物进行抗菌、抗肿瘤、抗病毒活性分析.采用利福霉素抗性及氢氧化钠显色初步鉴定安莎类化合物;采用α-萘酚硫酸显色初步鉴定6DOH糖基化修饰的化合物.利用16S rRNA序列对部分阳性菌株进行系统发育分析.结果 共获得39株AHBA合酶基因阳性和10株dTDP-葡萄糖-4,6-脱水酶基因阳性菌株.阳性菌株中,78%具有不同程度的生物活性.化学初步鉴定结果表明:49%的AHBA合酶基因阳性菌株产生安莎类化合物:50%的dTDP-葡萄糖-4,6-脱水酶基因阳性菌株产生6DOH糖基化修饰的化合物.系统发育分析表明,大多数阳性菌株属于放线菌中的链霉菌属.结论 基因探针筛选可作为一种合理、有效的方法从海洋细菌中发现活性代谢产物.

A strategy for discovery of bioactive metabolites from marine bacteria

Objective To screen ansamycin and 6-deoxyhexoses (6DOH) glycosylated secondary metabolites producers from more than 700 marine-sediment bacteria. Methods A gene-probe screening strategy was established targeting the 3-amino-5-hydroxybenzoic acid (AHBA) synthase and dTDP-glucose-4,6-dehydratase genes for discovering ansamycins and 6DOH glycosylated secondary metabolites, respectively. Bioactivities of the AHBA synthase and dTDP-glucose-4,6-dehydratase gene-positive strains were evaluated, including anti-bacterial, anti- tumoral and anti-viral activities. Rifamycin resistance profiles and color reactions with sodium hydroxyl or α naphthol were performed as preliminary identification of potential ansamycin or 6DOH glycosylated secondary metabolite producers. Taxonomic and phylogenetic analysis of some positive strains was conducted using partial 16S rRNA sequences. Results In total, 39 AHBA synthase gene-positive and 10 dTDP-glucose-4,6-dehydratase gene-positive strains were obtained. Of these positive strains, 78% showed varying degrees of biological activities. Preliminary chemical identification of metabolites showed that 49% of AHBA synthase gene-positive strains probably produced ansamycins while 50% of dTDP-glucose-4,6-dehydratase gene-positive strains might produce 6DOH glycosylated compounds. Taxonomic and phylogenetic analysis indicated that most of these positive strains belonged to Streptomyces. Conclusion The results suggested that gene-probe screening was a rational and effective strategy for discovering bioactive metabolites from marine bacteria.