Biodegradation of high molecular weight PAHs in contaminated soil

污染土壤中高分子量多环芳烃的生物降解

• 批准号: 6666412
• 负责人: MICHAEL AITKEN
• 金额: $ 17.52万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6666412
• 关键词: bacteria; bioreactors; biotransformation; carbopolycyclic compound; chemical carcinogen; environmental contamination; environmental toxicology; ground water; hazardous substances; industrial waste; microorganism metabolism; molecular weight; soil microbiology; soil pollution; soil sampling; toxin metabolism; waste treatment

Polycyclic aromatic hydrocarbons (PAH) are major contaminants in soil and groundwater at a number of sites across the U.S. Many of the PAH 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 sites, but removal of the high-molecular weight, carcinogenic species is often incomplete. Since these compounds are poorly soluble in water, their biodegradation of some of the PAH in contaminated systems is limited by factors other than bioavailability. The purpose of this project is to develop approaches by which the factor(s) that limit the degradation of PAH which appear to resist biodegradation can be identified and, eventually, overcome. Such factors can include the absence of significant numbers of microbes able to degrade these compounds; inherently very low rates of degradation of the compound by all organisms, which may be exacerbated by the presence of other PAH; loss of growth substrates for the microorganisms over time and consequent loss of PAH-degrading activity; loss of growth substrates for the microorganisms over time and consequent loss of PAH-degrading activity; and accumulation of products of incomplete metabolism that may inhibit the degradation of one or more PAH. Achievable removals of the carcinogenic PAH may determine whether active bioremediation is an acceptable technology at a given site. In addition, under emerging risk-based approaches to site management such of the PAH contamination is expected to be left in place at many sites. To understand the limits of natural attenuation and potential long-term risks at such sites, it is essential to improve our knowledge of the rates of PAH degradation and the factors that influence these rates. The proposed research will quantify rates of degradation of high-molecular weight PAH by bacteria isolated from a variety of contaminated soils and the effect of other PAH in mixtures on these rates. Then, actual contaminated soils from an industrial site will be treated will be treated in a bench-scale bioreactor to study the degradation of one or more apparently recalcitrant PAH. The factor(s) that govern the degradation of these compounds will be elucidated by: (i) quantifying the organisms in the treated soil that are capable of degrading of these compounds will be elucidated by: (i) quantifying the organisms in the treated soil that are capable of degrading the recalcitrant PAH; (ii) evaluating the effects of adding readily- degraded, naturally occurring compounds known to stimulate PAH degradation; (iii) examining whether the liquid phase in the bioreactor is inhibitory to PAH-degrading bacteria as a result of metabolite accumulation; and (iv) examining the role of bioavailability in the apparent recalcitrance of these compounds. With knowledge of the factor(s) most responsible for limited degradation of the target compound(s), we will then explore methods of stimulating biodegradation either directly in the bioreactor in treated soil removed from the bioreactor.

多环芳族烃（PAH）是美国多个地点的土壤和地下水中的主要污染物，许多PAH都是已知或怀疑的致癌物，但许多PAH也被认为是细菌和真菌本地土著和污染土壤的生物降解。生物过程已被用来补充受PAH污染的位点，但是去除高分子重量，致癌物种通常不完整。由于这些化合物可溶于水，因此它们对受污染系统中某些PAH的生物降解受到生物利用度以外的其他因素的限制。该项目的目的是开发方法，通过这种方法可以识别出限制PAH降解的因素，可以识别出抗生物降解的因素，并最终克服。这些因素可能包括没有大量能够降解这些化合物的微生物；本质上，所有生物体对化合物的降解速率非常低，这可能会因其他PAH的存在而加剧。随着时间的推移，微生物的生长底物损失，随之而来的PAH降解活性丧失；随着时间的推移，微生物的生长底物损失，随之而来的PAH降解活性丧失；以及不完全代谢产物的积累，可能抑制一个或多个PAH的降解。可实现的致癌PAH可以实现的去除可以确定主动生物修复是否是特定部位可接受的技术。 此外，在基于新兴风险的现场管理方法下，预计PAH污染的许多站点都将在许多地点保留。要了解此类站点的自然衰减和潜在长期风险的局限性，必须提高我们对PAH降解率的了解以及影响这些速率的因素。拟议的研究将量化从各种受污染的土壤中分离出的细菌对高分子重量PAH降解的速率，以及其他PAH在混合物中对这些速率的影响。然后，将在台式生物反应器中处理工业部位的实际污染土壤，以研究一种或多个显然是顽固的PAH的降解。控制这些化合物的降解的因子将通过以下方式阐明：（i）量化处理土壤中能够降解这些化合物的生物体，将通过以下方式阐明：（i）量化处理土壤中有生物体的生物体，能够降解恢复质量的pah pah; （ii）评估添加易于降解的，自然存在的化合物的效果，已知会刺激PAH降解； （iii）检查生物反应器中的液相是否由于代谢物积累而抑制了降解PAH的细菌； （iv）检查生物利用度在这些化合物的明显恢复中的作用。了解最负责目标化合物降解的因素，我们将探索直接在从生物反应器中去除的处理土壤中的生物反应器中刺激生物降解的方法。