Project 5: Beyond Parent Compound Disappearance In The Bioremediation Of Polycycl

生物修复是一种从污染土壤中去除多环芳烃的成熟技术，但以前的研究表明，它并不总是导致毒性降低。毒性的原因以及避免或减少毒性的机制尚不清楚。我们假设，PAH降解细菌产生的代谢产物，已被观察到在现场污染的土壤和沉积物中积累，至少部分负责可能导致的毒性， 生物修复。我们还假设，生物修复条件影响社区的多环芳烃降解微生物在污染的土壤中，这反过来又影响多环芳烃的去除和代谢产物可能积累的程度。以浆相生物反应器为实验平台，研究了生物修复条件对多环芳烃去除和土壤毒性的影响。我们将评估的条件之一是添加低剂量的疏水表面活性剂，我们 近年来研究表明，生物修复技术可以提高农田污染土壤中多环芳烃的生物有效性和生物降解性。这种方法将通过在半连续过程中证明其有效性来进一步发展。我们将联合收割机结合我们最近的工作稳定同位素探测与高通量DNA测序方法，以确定多环芳烃降解细菌最有可能影响多环芳烃去除，代谢物积累，并在处理过的土壤中的毒性。这些基因组 将对微生物进行测序，以确定与PAH代谢相关的基因，并表达关键基因。代谢各种多环芳烃的能力的差异将与这些基因的序列差异，使代谢物积累的遗传决定因素可以确定。与此同时，我们将使用分馏技术和先进的分析工具，以确定负责处理土壤的毒性化合物。最后，将评估生物修复过程中可以控制的变量，以确定其排除或减轻毒性的能力。我们的总体目标是填补知识的关键空白，这将为生物修复的实地应用提供信息和改进，从而真正降低风险。

Bioremediation is an established technology for removing PAHs from contaminated soil, but previous studies have shown that it does not always lead to a reduction in toxicity. The causes of toxicity and the mechanisms by which toxicity might be avoided or diminished are not well-understood. We hypothesize that metabolites produced by PAH-degrading bacteria, which have been observed to accumulate in field-contaminated soil and sediment, are responsible at least in part for the toxicity that can result from bioremediation. We also hypothesize that bioremediation conditions influence the community of PAH-degrading microorganisms in contaminated soil, which in turn influences both PAH removal and the extent to which metabolites might accumulate. We propose to explore the effects of bioremediation conditions on PAH removal and soil toxicity, using a slurry-phase bioreactor as the experimental platform. Among the conditions we will evaluate is the addition of a hydrophobic surfactant at a low dose, which we recently demonstrated can improve the bioavailability and biodegradation of PAHs that remained in a field-contaminated soil after conventional bioremediation. This approach will be developed further by demonstrating its efficacy in a semi-continuous process. We will combine our recent work on stable-isotope probing with a high-throughput DNA sequencing method to identify the PAH-degrading bacteria most likely to influence PAH removal, metabolite accumulation, and toxicity in the treated soil. Genomes of these organisms will be sequenced to identify genes associated with PAH metabolism, and the key genes will be expressed. Differences in the ability to metabolize various PAHs will be correlated to sequence differences in these genes so that genetic determinants of metabolite accumulation can be identified. In parallel, we will use fractionation techniques and advanced analytical tools to identify compounds responsible for toxicity of the treated soil. Finally, variables that can be controlled during bioremediation will be evaluated for their ability to preclude or mitigate toxicity. Our overall goal is to fill key gaps in knowledge that will inform and improve field applications of bioremediation that lead to true reductions in risk.