种间竞争和铁营养胁迫下易变链霉菌抗生素和铁载体代谢的化学响应机制研究

Antibiotics and siderophores are two types of metabolites produced by mycroorganisms, which play a vital role in investigating the competition relationship and the mechanism of ecological adaption.It is a scientific question whether actinomyces simultaneously use antibiotics and siderophore as chemical weapons to make them be more adapted to ecological environment under the pressure of nutrition limitation or the interspecific competition. In the former researching,actinomyces D(an antibiotic) and desferrioxamine E (a siderophore) were isolated and identified from Streptomyces mutabilis TRM 45540. On basis of this result, this project aims to investigate the chemical response mechanism of S.mutabilis via the secondary metabolism of antibiotics and siderophores under the condition of nutrition limitation, interspecific competition and in the continuous cultured cotton field soil as well as the effects of S. mutabilis and its metabolites on the soil inhabitant group of microbes such as Verticillium dahliae. This research will enrich the knowledge of the adaption of actinomyces via secondary metabolism modification and provide a new way for the biological control of diseases.

抗生素和铁载体是微生物产生的两类次生代谢产物，对探索微生物种间竞争关系和适应生态环境机制具有重要意义。放线菌在面临营养胁迫和种间竞争压力时是否联合使用或改变这两类"化学武器"的结构与含量以使其更好地适应生态环境是一个未知的科学问题。课题组前期从易变链霉菌Streptomyces mutabilis TRM 45540中分离鉴定了一种抗生素- - 放线菌素D和一种铁载体- - 去铁胺；本项目拟在前期研究的基础上，探索在铁营养胁迫、种间竞争和连作棉田土壤微生态条件下易变链霉菌为增进生态适应性而调节抗生素和铁载体代谢的化学响应机制及其对棉花黄萎病等土壤习居菌群的生态影响。项目的开展不但能够加深人们对放线菌通过调控次生代谢适应生态环境的理解，还能为病原菌的生物防治提供新思路。

抗生素和铁载体是微生物产生的两类次生代谢产物，项目以易变链霉菌Streptomyces mutabilis TRM45540为研究对象，探索了放线菌在面临营养胁迫和种间竞争压力时抗生素和铁载体这两类次生代谢产物的化学响应机制。研究表明，抗生素和铁载体作为放线菌的两类“化学武器”在逆境胁迫条件下存在代谢关联性，铁匮乏和竞争胁迫条件下，放线菌通过激活去铁胺E的生物合成并调节发育来促进放线菌素D的上调表达；高浓度铁离子胁迫条件下，放线菌首先激活铁离子转运，然后通过双组份调节系统来促进放线菌素D的超量表达（产量超1g/L），同时还激活了四烯类沉默基因簇匹马菌素类似物的表达。易变链霉菌与棉花黄萎病菌的种间斗争主要依靠抗生素放线菌素D而不是铁载体去铁胺E，放线菌素D杀菌作用机制主要通过裂解棉花黄萎病菌孢子或菌丝的膜系统从而导致细胞肿胀破裂而起作用。项目的开展加深了人们对抗生素和铁载体次生代谢及其放线菌化学生态适应性的理解，并为棉花黄萎病的生物防治提供了新思路。