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Studies on the cultures of isolated symbionts of lichens and mixed cultures of both symbionts as new sources of bioactive compounds

地衣分离共生体培养物和两种共生体混合培养物作为生物活性化合物新来源的研究

基本信息

批准号：
15510186
负责人：
TANAHASHI Takao
金额：
$ 2.37万
依托单位：
Kobe Pharmaceutical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

Lichens are symbiotic organisms comprised of a fungus, mycobiont, and a photosynthetic partner, photobiont. In some cases, cultures of lichen mycobionts have an ability under osmotically stressed conditions to produce new substances. It was pointed out that cultures of lichen mycobionts could be new sources of bioactive compounds. In the course of our studies on cultured lichen mycobionts, we cultivated mycobionts of the lichens collected in Japan and investigated their metabolites. From the cultures of Graphis proserpens, three new isocoumarins and three novel compounds derived from naphthopyrones through an oxidative ring cleavage were isolated along with six known compounds. From the cultured mycobionts of Graphis connectans, three new compounds were obtained and their structures were also elucidated.The diverse metabolites of the cultured mycobionts have never been found in the lichenized state. The finding suggested that the secondary metabolism of mycobionts could be influenced by the algal partner in symbiosis. We investigated the conditions which trigger re-synthesis of the isolated mycobiont and photobiont. In the mixture of both symbionts cultured together on agar medium, mycobiont colonies were in contact with the surface of the algal layer, but neither mycobiont species penetrated the algal cells. On the other hand, the attachment between the mycobiont and algae in the liquid medium was observed and in the center of the mixture, branched mycobiont hyphae often penetrated algal cells. The combination between algae and mycobionts in some experiments was different from the natural lichens and this mismatch may explain the occurrence of parasitism instead of symbiosis. Further studies to elucidate the factors which induce the re-synthesis of the two components could give important information about the symbiosis of lichens and good tools for the production of useful secondary products.

地衣是一种共生生物，由真菌、真菌和光合作用伙伴光生生物组成。在某些情况下，地衣真菌培养物在渗透胁迫条件下具有产生新物质的能力。指出地衣真菌培养物可作为生物活性物质的新来源。在对地衣真菌的培养研究过程中，我们对从日本采集的地衣进行了真菌培养，并对其代谢产物进行了研究。从石墨菌的培养物中分离得到了3个新的异香豆素和3个新化合物，其中3个是由萘比酮通过氧化裂环得到的，还有6个化合物。从培养的Graphis Connectans真菌中分离得到3个新化合物，并对它们的结构进行了鉴定，在地衣状态下从未发现过这些真菌的代谢产物。这一发现表明，共生中的藻类伙伴可能会影响真菌的次生代谢。我们研究了引发分离的真菌生物体和光生物体重新合成的条件。在琼脂培养基上共同培养的两种共生菌中，真菌菌落与藻层表面接触，但两种真菌均未穿透藻细胞。另一方面，在液体介质中观察到真菌与藻类之间的附着，在混合物的中心，分枝的真菌菌丝经常穿透藻细胞。在一些实验中，藻类和真菌的结合不同于天然地衣，这种不匹配可能解释了寄生而不是共生的发生。进一步研究导致这两种成分重新合成的因素可能会为地衣的共生提供重要信息，并为生产有用的次生产品提供良好的工具。