Investigating the ecology, activity and interactions of microorganisms bioremediating aquatic ecosystems contaminated with recalcitrant compounds.

多环芳烃是化石燃料的天然成分，被列为重点持久性污染物（PPP）。在英国，多环芳烃污染在环境中很普遍。高分子量多环芳烃（HMW-PAHs）是一种高毒性、难降解的化合物，可以从一个营养水平到另一个营养水平进行生物放大，对水生生态系统造成严重的环境问题。除了高分子量多环芳烃外，在超稠油的提取和加工过程中还会产生大量的废水（称为尾矿池水，TPW）。这种工艺用水含有被称为环烷酸（NAs）的剧毒有机化合物的复杂混合物。在TPW中存在高浓度的NAs (40-120 mg l-1)，并且对环境中的许多生物，包括人类、鱼类和微生物具有高度毒性（Dokholyan & Magomedov, 1983; Clemente et al., 2004）。目前，受污染的废水被储存在巨大的池塘中，直到其毒性降低到可接受的水平，以便纳入回收计划。预计到2025年，工艺用水容量将达到10亿立方米，在储存过程中存在大规模环境污染的重大风险。因此，去除NAs和高分子量多环芳烃对环境、社会和经济都具有重要意义。虽然高分子量多环芳烃和NAs是环境中毒性最强、最难降解的有机污染物，但它们也是研究最少的污染物之一。NAs和HMW-PAHs污染的水生系统对环境和人类健康构成严重威胁。该项目除具有明显的社会效益和环境效益外，还将产生巨大的经济效益。微生物处理NAs和HMW-PAHs具有明显的成本和环境优势。该项目的主要产出将是开发成本效益高、对严重污染的水生系统进行快速生物修复的技术。我们将开发新的策略和工具来增强污染环境中NAs和hw - pahs的生物降解。通过提高原地生物降解率，受污染的废水可以更快地解毒，加速纳入回收计划并消除昂贵的储存费用。这项研究将使我们能够更好地了解微生物的生态、多样性和活性，这些微生物负责降解这些顽固的有毒化合物。我们将研究如何利用新的微生物相互作用和降解途径来提高降解率。然而，HMW-PAHs和NAs的转化过程非常复杂，受微生物活动和相互作用、生物地球化学因素以及化合物的物理化学性质的综合影响。因此，有必要采用跨学科的方法，从纯文化到微观社区和实地研究等多个层面来研究这一过程。主要重点将是确定在水生环境中负责NA和HMW-PAH生物降解的关键生物。我们将研究微生物的相互作用，获得并优化可降解的纯培养物和菌群，并验证其在TPW、其他复杂废水和受污染的淡水系统中的降解/解毒能力。我们将跟踪降解过程、代谢物积累、毒性、生物表面活性剂生产和微生物群落组成、多样性和活性。我们将根据环境中发现的主要微生物的分子分析、新分离物和文献数据设计基因探针。然而，关于NA降解微生物的代谢途径几乎一无所知（因此我们缺乏合适的基因探针），因此该学生将在UoE开展研究，开始阐明NA分解代谢途径。一个关键的项目产出是鉴定具有原位降解NAs和高分子量多环芳烃能力的微生物，并优化提高生物降解率的策略/联盟。

PAHs are natural components of fossil fuels, and are classified as Priority Persistent Pollutants (PPP). In the UK, PAH contamination is widespread in the environment. High molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) are highly toxic, recalcitrant compounds which can be biomagnified from one trophic level to another, causing significant environmental problems in aquatic ecosystems. In addition to HMW-PAHs, vast quantities of wastewaters are generated (known as tailing pond waters, TPW) during the extraction and processing of super heavy oils. Such process waters contain complex mixtures of highly toxic organic compounds known as naphthenic acids (NAs). NAs are present in TPW in high concentrations (40-120 mg l-1) and are highly toxic to many organisms in the environment including humans, fish and microorganisms (Dokholyan & Magomedov, 1983; Clemente et al., 2004). Currently, contaminated wastewaters are stored in vast ponds until their toxicity is reduced to acceptable levels for incorporation into reclamation schemes. With the volume of process waters expected to reach 1 billion m3 by 2025, there is a significant risk of large-scale environmental pollution during storage. Thus, removing both NAs and HMW-PAHs is important to the environment, society and economy. Although HMW-PAHs and NAs are among the most toxic, recalcitrant organic pollutants found in the environment, they are also among the least studied. Aquatic systems contaminated with NAs and HMW-PAHs pose a severe threat to the environment and human health. As well as the obvious societal and environmental benefits for remediating NAs and HMW-PAHs, the project will provide great economic benefits. Microbial treatment of NAs and HMW-PAHs has clear cost and environmental advantages. The main project output will be the development of cost-effective, rapid bioremediation of severely contaminated aquatic systems. We will develop novel strategies and tools to enhance the biodegradation of NAs and HMW-PAHs from contaminated environments. By increasing in situ biodegradation rates, polluted wastewaters can be detoxified more quickly, accelerating incorporation into reclamation schemes and removing expensive storage costs. This study will enable us to better understand the ecology, diversity and activity of the microbes responsible for the degradation of these recalcitrant, toxic compounds. We will investigate how novel microbial interactions and degradation pathways can be exploited to enhance degradation rates. However, the transformation of HMW-PAHs & NAs is very complex and influenced by a combination of microbial activities and interactions, biogeochemical factors and the physical-chemical properties of the compound. Therefore, it is necessary to adopt a cross-disciplinary approach to investigate the processes at multiple levels, from pure cultures to communities in microcosms and field studies. The main focus will be to identify the key organisms responsible for NA and HMW-PAH biodegradation in aquatic environments. We will investigate the microbial interactions, obtain and optimize degrading pure cultures and consortia, and validate degradation/ detoxification capacity in TPW, other complex wastewaters and contaminated freshwater systems. We will follow the degradation process, metabolite accumulation, toxicity, biosurfactant production and microbial community composition, diversity and activity. We will design gene probes based on molecular analysis of the main microbes found in the environment, new isolates and data from the literature. However, almost nothing is known about the metabolic pathways of NA-degrading microbes (and thus we lack suitable gene probes), and so the student will develop the research at UoE that has begun to elucidate NA catabolic pathways. A key project output is to identify microbes with the ability to degrade NAs and HMW-PAHs in situ and optimise strategies/consortia for increasing biodegradation rates.