Physiological and Genetic Basis of Microbial Resistance to Copper

铜从许多来源释放到环境中，包括燃烧化石燃料和木制品、采矿和冶炼业务，以及通过在农业中应用铜化合物来控制植物疾病。铜在某些土壤和水系统中积累到对植物、动物和微生物造成毒性影响的水平。人们对生物体如何适应铜含量的增加知之甚少，但这些信息可能在设计铜解毒方法或基因改造植物和有益微生物以增加对铜的耐受性方面具有实用价值。库克西博士从一个农业系统中分离出了抗铜细菌，在这个系统中，铜化合物通常被用于植物上，以控制细菌疾病。他还克隆并部分描述了决定铜抗性的基因。本研究旨在进一步研究该系统的遗传特征，探讨其抗铜性的生理基础。由于这些细菌积累了大量的铜，所以它们变成了亮蓝色，这个系统可能涉及一种独特的金属抗性机制；其他已知的金属抗性系统通常包括排除有毒金属（减少积累），或通过还原或甲基化对金属进行解毒。该提案中描述的分子遗传学和生物化学相结合的方法应该为微生物如何适应铜的有毒水平以及它们如何在分子水平上与这种金属相互作用提供新的基本信息。

Copper is released into the environment from many sources, including the burning of fossil fuels and wood products, mining and smelting operations, and through the application of copper compounds in agriculture for plant disease control. Copper has accumulated in certain soils and water systems to levels that have caused toxic effects on plants, animals, and microorganisms. Little is known about how organisms can adapt to increased levels of copper, but such information could have practical value in designing methods for detoxifying copper or for genetically modifying plants and beneficial microbes for increased tolerance to copper. Dr. Cooksey has isolated copper-resistant bacteria from an agricultural system where copper compounds are routinely applied to plants for bacterial disease control. He has also cloned and partly characterized the genes that determine copper resistance. This proposal is to further characterize the genetics of this system, and to investigate the physiological basis for copper resistance. Since these bacteria accumulate high levels of copper, such that they become bright blue, this system probably involves a unique mechanism of metal resistance; other known metal resistance systems usually involve either the exclusion of the toxic metal (with reduced accumulation), or the detoxification of the metal by reduction or methylation. The combined molecular genetic and biochemical approaches described in the proposal should provide new fundamental information on how microorganisms can adapt to toxic levels of copper and how they interact with this metal at the molecular level.