BACTERIAL DEGRADATION AND INTERACTIONS OF POLYNUCLEAR AROMATIC HYDROCARBONS

多环芳烃(PAH)是土壤和土壤中的主要污染物 美国各地许多地点的地下水。他们中的许多人 是已知的或可疑的致癌物，但许多也是已知的 可被本土和受污染的细菌和真菌生物降解 土壤。生物法已被用于修复被污染的多环芳烃 土壤，但去除了高分子量(HMW)、致癌物质 往往是不完整的。对HMW多环芳烃的生物降解知之甚少 (定义为具有四个或更多环的环)比已知的 二环和三环化合物的降解。一些细菌最近已经 被发现生长在四环多环芳烃上，而其他人只代谢这些 化合物。 本项目的目的是研究新陈代谢和生物降解性。 HMW PAH，特别强调识别不完整的产品 可能在水相中积累的代谢；研究动力学 以评估其他多环芳烃对降解速率的影响。 HMW PAH在混合物中存在时的降解；评估潜力 HMW多环芳烃代谢的诱导剂可能被用来维持 在其主要生长底物后共代谢HMW PAH的细菌 是耗尽的；以评估传质过程对 HMW多环芳烃的降解速度和程度；以及评估战略以 提高HMW PAH在传质受限条件下的降解程度 情况。这些目标将通过使用多环芳烃降解菌来实现 从各种受污染的土壤中分离出来，似乎含有 多环芳烃代谢的不同途径/其中一些细菌也有 可使它们影响传质过程的特性。 这些细菌将被筛选，以寻找代谢物产生的证据 放射性标记底物的光谱方法和质量平衡。 代谢物的分析将大量使用进化技术 光谱分析，以帮助识别极性、非挥发性化合物。 感兴趣的传质过程包括多环芳烃从非 土壤有机质的水相和解吸。量化 将开发模型以确定生物降解可以被量化 使用独立测量的速率参数，并作为识别 那些可能影响传质过程的生物体。战略以实现 提高HMW-PAH作为生长基质的生物降解性 以及使用非离子表面活性剂来提高生物利用度 这些化合物。

Polycyclic aromatic hydrocarbons (PAH) are major contaminants in soil and groundwater at a number of sites across the United States. Many of them are known or suspected carcinogens, yet many are also known to be biodegradable by bacteria and fungi indigenous to native and contaminated soils. Biological processes have been used to remediate PAH contaminated soils, but removal of the high molecular weight (HMW), carcinogenic species is often incomplete. Far less is known about the biodegradation of HMW PAH (defined as those with four or more rings) than is known about the degradation of two- and three ring compounds. Some bacteria recently have been found to grow on four-ring PAH, while others only cometabolize these compounds. The purposes of this project are to study the metabolism and biodegradation of HMW PAH, with particular emphasis on identifying products of incomplete metabolism that may accumulate in the aqueous phase; to study the kinetics of HMW PAH degradation; to asses the influence of other PAH on the rate of HMW PAH degradation when present in mixtures; to evaluate potential inducers of HMW PAH metabolism which might be used to sustain the growth of bacteria that cometabolize HMW PAH after their principal growth substrates are depleted; to evaluate the influence of mass transfer processes on the rate and extent of HMW PAH degradation; and to evaluate strategies to increase the extent of HMW PAH degradation in mass transfer-limited situations. These aims will be met using PAH degrading bacteria already isolated from a variety of contaminated soils and which appear to contain different pathways for PAH metabolism/ some of these bacteria also have characteristics which may allow them to influence mass transfer processes. These bacteria will be screened for evidence of metabolite production using spectroscopic methods and mass balances with radiolabeled substrates. Analysis of metabolites will employ evolving techniques in mass spectrometry to aid in the identification of polar, non-volatile compounds. Mass transfer processes of interest include dissolution of PAH from non- aqueous phases and desorption from soil organic matter. Quantitative models will be developed to ascertain that biodegradation can be quantified using independently measured rate parameters, and as a tool in identifying those organisms that may influence mass transfer processes. Strategies to improve the biodegradability of HMW PAH will pounds as growth substrates and the use of nonionic surfactants to increase the bioavailability of these compounds.