Pilot Proposal: Connecting methane oxidation rates to mineral sources of copper

拟议的研究将调查矿物溶解速率、矿物中铜的浓度和甲烷营养微生物（例如从温室气体甲烷中获取能量的细菌）的甲烷氧化速率之间的联系。pi先前的研究已经确定并表征了一种细胞外铜结合分子——甲烷obactin，该分子在实验室研究中已被证明能够影响矿物溶解速率和甲烷氧化酶的活性。这些发现表明，土壤、沉积物和水中铜的可用性与大气中甲烷浓度的生物调控之间存在着令人信服的联系。本研究将包括受控的非生物和生物实验室实验，使用矿物相（在其结构中具有不同浓度的铜），模型甲烷氧化菌Methylosinus trichosporium OB3b （II型）和铜结合分子甲烷obactin来研究矿物溶解的机制和程度，以及甲烷氧化速率。我们这个试点方案的具体研究目标是确定特定含铜矿物相和甲烷菌的存在如何影响甲烷营养菌的生长和甲烷氧化速率，以及甲烷营养活性是否影响矿物溶解速率。这项研究的更广泛的影响将源于对控制甲烷氧化的生物和地质反馈的全面理解，这反过来又是全球碳循环的一个主要方面。作为这个试点计划的教育组成部分，pi将让本科生参与与提议的研究相关的动手实验。学生将学习如何分离和纯化甲烷菌，如何在连续培养中培养甲烷氧化菌，并进行自己的培养实验。本研究将阐明甲烷（一种强效温室气体）氧化速率的控制，并将甲烷氧化活性与环境中的矿物学控制联系起来。

The proposed research will investigate linkages between mineral dissolution rates, concentrations of copper in minerals, and methane oxidation rates by methanotrophic microorganisms (e.g. bacteria that derive energy from the greenhouse gas methane). Previous research by the PIs has identified and characterized an extracellular copper-binding molecule, methanobactin, that has been shown in laboratory studies to influence mineral dissolution rates and the activity of methane oxidizing enzymes. These findings, suggest a compelling link between the availability of copper in soils, sediments, and water, and the biogenic regulation of the atmospheric concentrations of methane.This research will include controlled abiotic and biotic laboratory experiments using mineral phases (with differing concentrations of copper in their structure) a model methanotroph Methylosinus trichosporium OB3b (type II), and the copper-binding molecule methanobactin to investigate mechanisms and extent of mineral dissolution, and methane oxidation rates. Our specific research objectives for this pilot proposal are to determine how the presence of specific copper bearing mineral phases and methanobactin influences methanotroph growth and methane oxidation rates and if methanotrophic activity influences mineral dissolution rates.The broader impacts of this study will stem from a holistic understanding of biological and geological feedbacks controlling methane oxidation and in turn a major facet of the global carbon cycle. As part of our educational component of this pilot proposal the PIs will involve undergraduate students in a hands-on experiment related to the proposed research. Students will learn how to isolate and purify methanobactin, how to grow methanotrophs in continuous culture, and they will conduct their own incubation experiments. This study will elucidate controls on oxidation rates of methane a potent greenhouse gas and link methanotrophic activity to mineralogical controls in the environment.