Collaborative Research: CMG--Toward Understanding the Transfer of Genetic Information in Subsurface Hydrology

几十年来，遗传信息在环境中的传递一直是科学家和公众关注的一个重要问题。随着对致病菌的抗生素耐药性的迅速蔓延，它的重要性首次显现出来。基因组分析表明，基因转移在细菌进化中发挥了重要作用。最近，公众对基因工程生物向本地生物转移的风险以及可能对环境造成的后果表示关注。细胞间转移是基因在自然地质构造中向交替宿主传播的主要手段之一。虽然这一过程已经被记录下来，并且交换是在实验室条件下进行的，但人们对地下这些事件的频率知之甚少。自然地质环境是异质的，因此不可能在不同的尺度上对每一个变量进行实验测试。通过将实验与理论相结合，研究人员的目标是确定成功基因转移的主要要求及其在特定条件下发生的速率。环境中细菌之间遗传物质的转移既可以发生在浮游状态，也可以发生在附着状态。本研究的重点是数学的发展和应用，以描述与地下生物膜内水平基因转移相关的基本方面。用于描述细菌在多孔介质中运输的数学一直集中在单细胞或细胞团运输的胶体运输机制上。到目前为止，这两个领域几乎完全彼此隔离。在这里，研究人员提出了实验和模型，旨在测试多孔介质中多尺度转移的假设，并阐明细菌之间在运输、附着和生物膜形成过程中控制转移的优先机制。

The transfer of genetic information in the environment has been an important issue among scientists and the public for several decades. Its importance first became apparent with the rapid spread of antibiotic resistance to pathogenic bacteria. Then genomic analysis revealed that gene transfer has played an important role in bacterial evolution. Recently there have been public concerns about risks associated with gene transfer from genetically engineered organisms to indigenous organisms and the possible consequences in the environment. Cell to cell transfer is one of the primary means by which genes can be propagated in natural geologic formations into alternate hosts. Although the process has been documented and exchange occurs under laboratory conditions, very little is known about the frequency of these events in the subsurface. The natural geologic environment is heterogeneous, and therefore it has been impossible to test every variable experimentally over a hierarchy of scales. By combining experiment with theory the investigators target identification of the major requirements for successful gene transfer and the rates at which it occurs under particular conditions. The transfer of genetic material among bacteria in the environment can occur both in the planktonic and attached state. This study focuses on the development and application of mathematics to describe the fundamental aspects associated with horizontal gene transfer within biofilms in the subsurface. The mathematics used to describe bacterial transport in porous media has been focused on colloid transport mechanisms for single cell or cell clump transport. These two fields are so far in nearly complete isolation from each other. Here the investigators propose experiments and modeling designed to test hypotheses regarding transfer in porous media at multiple scales, and to elucidate priority mechanisms controlling transfer among bacteria undergoing transport, attachment, and biofilm formation.