The Role of Bacterial Chemotaxis in the Biodegradation of Naphthalene in Porous Media

细菌趋化性在多孔介质中萘生物降解中的作用

• 批准号: 9807666
• 负责人: Michael Aitken
• 金额: $ 21.5万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2000-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9807666&HistoricalAwards=false
• 关键词: Role; Bacterial; Chemotaxis; Biodegradation; Naphthalene

Aitken 9807666 There is considerable interest in methods of remediating contaminated soil and ground water by in situ processes, particularly if remediation can be accomplished through natural processes such as biodegradation by indigenous microorganisms. To properly evaluate and develop in situ bioremediation methods, it is important to understand the dominant physical, chemical and biological processes. Biological processes are perhaps the least understood of these. The investigator and his colleagues focus on the potential role of bacterial chemotaxis in the biodegradation of common soil pollutants in porous media. They study the biodegradation of naphthalene, a common soil pollutant, by Pseudomonas putida G7 in a model porous medium consisting of uniform glass beads. The effect of chemotaxis is evaluated by comparing the rates of mineralization of naphthalene by the chemotactic wild-type strain and by an immotile or non-chemotactic mutant strain with the same inherent kinetics of naphthalene degradation as the wild-type. A mathematical model is constructed that incorporates the most significant chemical and biological phenomena in the experimental system. The model is used to quantify the chemotactic and random motility coefficients of the organism as a function of the size of the glass beads, and to evaluate the relative influences of random motility and chemotactic motility in naphthalene biodegradation. Chemical contamination of soil and ground water is an enormous problem in the U.S. The cost of cleaning up contaminated sites can be reduced dramatically if the contaminated materials do not have to be excavated or pumped to the surface for treatment or disposal; consequently there is great interest in taking advantage of processes referred to as "natural attenuation." Many bacteria found in the subsurface are known to be able to degrade a variety of chemicals, but the behavior of bacteria in soil is relatively poorly understood. A commo n property of many bacteria is chemotaxis, an ability to move in response to the presence of a chemical. However, the potential role of chemotaxis in the biodegradation of pollutants in soil has not been explored before. It is likely, for example, that bacteria able to swim towards the sources of chemical contamination are able to degrade the contaminants faster than those bacteria unable to do so. The investigators in this project conduct experiments with a simulated soil environment and mathematical modeling techniques to evaluate the potential role of chemotaxis in the biodegradation of a pollutant found at many contaminated sites. An improved understanding of the role of chemotaxis will permit better characterization of the feasibility of natural attenuation processes, and may permit the development of strategies to accelerate the in situ treatment of contaminated sites that take advantage of bacterial chemotaxis.

Aitken 9807666 人们对通过原位处理修复受污染的土壤和地下水的方法非常感兴趣，特别是如果修复可以通过自然过程（例如本地微生物的生物降解）来完成。 为了正确评估和开发原位生物修复方法，了解主要的物理、化学和生物过程非常重要。 生物过程可能是其中最不为人所知的。 研究人员和他的同事重点研究细菌趋化性在多孔介质中常见土壤污染物生物降解中的潜在作用。 他们研究了恶臭假单胞菌 G7 在由均匀玻璃珠组成的多孔介质模型中对常见土壤污染物萘的生物降解作用。 通过比较趋化野生型菌株和具有与野生型相同的萘降解固有动力学的不动或非趋化突变菌株的萘矿化速率来评估趋化性的效果。 构建了一个数学模型，其中包含了实验系统中最重要的化学和生物现象。 该模型用于量化生物体的趋化和随机运动系数作为玻璃珠尺寸的函数，并评估随机运动和趋化运动在萘生物降解中的相对影响。 土壤和地下水的化学污染在美国是一个巨大的问题。如果不必挖掘受污染的物质或将其泵送到地表进行处理或处置，那么清理受污染场地的成本可以大大降低；因此，人们对利用被称为“自然衰减”的过程产生了极大的兴趣。 已知在地下发现的许多细菌能够降解多种化学物质，但人们对土壤中细菌的行为知之甚少。 许多细菌的一个共同特性是趋化性，即响应化学物质的存在而移动的能力。 然而，趋化性在土壤污染物生物降解中的潜在作用此前尚未被探索过。 例如，能够游向化学污染源的细菌可能比那些不能这样做的细菌更快地降解污染物。 该项目的研究人员利用模拟土壤环境和数学建模技术进行实验，以评估趋化性在许多污染场地发现的污染物生物降解中的潜在作用。 对趋化作用的进一步了解将有助于更好地表征自然衰减过程的可行性，并可能允许制定利用细菌趋化作用加速污染场地原位处理的策略。