Arms race drives evolution of metabolic diversity

　　报告题目: Arms race drives evolution of metabolic diversity

　　报告人: Jim Spain

　　报告人单位: Georgia Institute of Technology, the USA

　　报告时间: 2015年4月13日(星期一)上午10:30

　　报告地点: 微生物所A203会议室

　　主持人: 刘双江 研究员

　　报告摘要:Microorganisms have evolved a wide variety of strategies for the biodegradation of natural and synthetic chemicals, pesticides and antibiotics. The synthetic chemicals have only been in the biosphere for the past century- yet most simple synthetic organic compounds are now biodegradable. In many instances the enzymes involved in the catabolic pathways are closely related to the enzymes involved in degradation of natural compounds. Millions of natural organic chemicals are produced and degraded in natural ecosystems. Therefore, there is a huge reservoir of unexplored metabolic diversity among bacteria that catalyze the biodegradation.

　　Within a few years after new chemicals, pesticides or antibiotics enter the biosphere, pathways evolve to allow the compounds to support growth of bacteria. Often the chemicals must be modified to make them less susceptible to biodegradation if they are to remain effective. There seems to be a similar arms race in natural ecosystems among the organisms that engage in chemical communication and defense. Plants produce allelopathic chemicals to suppress competing species or pathogens. Once bacteria evolve the ability to degrade such chemicals their effectiveness would be reduced. Allelopathic plants often produce multiple analogs of the active chemicals which suggests the operation of an arms race among the plants, the target species and the bacteria. Stilbenes such as resveratrol are antifungal compounds produced by a variety of plants including peanuts and grapes. In peanuts resveratrol is accompanied by up to 20 different homologs. We found that resveratrol is readily biodegraded by a diverse community of bacteria in the rhizosphere. The initial enzyme has very limited activity toward the most common homologs of resveratrol which suggests they are more recently evolved and less susceptible to biodegradation. Such an arms race could account for many of the myriad small organic compounds produced in the biosphere. Understanding the ecological roles of bacterial catabolic pathways could provide the basis for interventions to limit the spread of invasive plants or improve the defenses of agriculturally important crops.