黑翅土白蚁相关放线菌的多样性及农用抗生素先导物的发掘

Plant pathogenic fungi are seriously harmful to the crops and it’s urgent to develop novel agricultural antibiotics. Fungus-growing insect used Actinobacteria to prevent harmful fungi in their agricultural systems for a long time. Learning from the fungus-growing insect and then exploring new agricultural antibiotics from the insect-associated Actinobacteria can increase the probability of success. We have isolated some antifungal Actinobacteria from the fungus-growing Odontotermes formosanus. Based on this result, we will systematically isolate the Actinobacteria associated with O. formosanus and analyse their diversity in this project. The antifungal activities of the isolated Actinobacteria against plant pathogenic fungi will be evaluated by the growth rate method. Furthermore, bioassay-guided fractionation of the bioactive constituents in the targeted Actinobacteria with better activity will be performed by many kinds of chromatograms. Finally, the chemical structures of bioactive metabolites will be elucidated by many spectral techniques. The project aims to discover antifungal strains and lead compounds from the Actinobacteria associated with O. formosanus and lay certain foundation for new agricultural antibiotics, so it has potential economic and social benefits.

植物病原真菌对作物危害严重，开展新型农用抗生素研制的意义重大。培菌昆虫在其农业系统中早就使用放线菌防治危害性真菌，向培菌昆虫“取经”，从昆虫相关放线菌资源中开发新型农用抗生素的成功率更高。我们前期已从培菌的黑翅土白蚁中分离到部分具有抗真菌活性的放线菌，在此基础上，本课题拟系统地从黑翅土白蚁中分离相关放线菌并分析其多样性；应用生长速率法评价其抗植物致病真菌活性；在活性跟踪指导下，进一步采用多种色谱法从具有较好抗菌活性的目标菌株中分离活性成分；采用多种波谱技术鉴定活性成分的结构。如获准实施，将会从黑翅土白蚁相关放线菌中发掘具有抗真菌活性的菌株和先导化合物，为开发新型农用抗生素奠定一定的基础，具有潜在的经济和社会效益。

主要对黑翅土白蚁相关放线菌的多样性及4株白蚁相关放线菌的抗菌等活性成分进行了分离和鉴定。具体分述如下：.1. 白蚁相关放线菌的多样性及抗菌活性.从黑翅土白蚁体表、肠道及菌巢中共分得111株放线菌，经鉴定源于4个不同属，21个不同种。活性测试表明约50 %的菌株有一定的抗菌活性；筛选到22株放线菌具有一定的抗植物致病真菌活性。.2. 白蚁相关放线菌Streptomyces sp. BYTB63的活性成分.从菌株S. tanashiensis BYTB63的次生代谢产物中分离纯化得到4个新活性化合物termstrin A-D (1-4)。活性测试表明化合物1和4对金黄色葡萄球菌的抑菌作用最好，抑菌圈直径分别为12.85和11.17 mm，与阳性对照青霉素钠相当，此外化合物1对癌细胞具有一定的抑制活性。.3. 白蚁相关放线菌S. tanashiensis BYF-112的活性成分.从S. tanashiensis BYF-112中共分离鉴定了17个化合物，包括8个新生物碱化合物vegfrecine A-B（1-2）, vegfrecine B （2）, exfoliazone A-D（3-6），venezueline H-I（7-8）。抗菌活性表明已知物viridomvcin A对四联球菌有中等抑制活性，抑菌圈直径为13.3 mm。除草活性结果显示新化合物4-5对稗草根具有较好的抑制活性。抗癌活性测试表明部分化合物表现出了较好的抑制活性，与阳性对照阿霉素活性相近。 .4.白蚁相关放线菌S. lannensis BYF106和S. malaysiensis T29的抗菌活性成分.从白蚁相关放线菌Streptomyces lannensis BYF106中分离得到2个单体化合物grincamycin N和fridamycin D，活性测试表明grincamycin N对金黄色葡萄球菌的抑制圈直径达到13.8 mm，与硫酸庆大霉素效果相当（抑菌圈直径为19.9 mm）。从白蚁相关放线菌Streptomyces malaysiensis T29分离得到2个单体化合物geldanamycin和17-O-demethylgeldanamycin，活性测试表明其对金黄色葡萄球菌的抑制圈直径分别为14.6 mm和14.5 mm，对白色念珠菌的抑制圈直径分别为14.5 mm和13.9 mm