Unique enzyme-biosurfactant caged mixes for biodegradation of high charge p-xylene contaminated sites

石油污染存在于圣劳伦斯河沿岸12-15米的深度。在该污染中存在的各种石油烃中，对二甲苯是最常见的，其在土壤中的浓度可达10000 mg/kg以上，而且还可以观察到不相溶的相(纯相)。事实上，这种土壤的净化是一项挑战，因为必须将地下水位降低到圣劳伦斯河附近(由于高渗透性)。由于对二甲苯的物理化学性质(即密度、挥发性等)，通常的方法，如过氧化氢或加热处理，不足以去除污染土壤中的对二甲苯。因此，需要一种替代策略，使用有效和独特的生物表面活性剂-酶混合物，以有效地解决对二甲苯的生物去污。该项目是基于这样的假设，即鼠李糖脂作为生物表面活性剂可以帮助形成胶束，胶束可以进一步作用于酶来实现生物降解。这一假设已经在我们的实验室中得到了验证，我们观察到生物表面活性剂-酶复合体可以帮助降解难降解的化合物，如对二甲苯。然而，仍需进行研究以了解有关生物表面活性剂和酶的动力学、相互作用及其在实地研究中的行为的细节。因此，该提案的具体目标包括：1)在实验室规模上选择和生产大量的酶；2)在试点规模上示范鼠李糖脂的生产；3)生物表面活性剂和酶的笼式配方；4)在柱中对生物表面活性剂-酶混合物进行实验室测试、动力学研究和配方的微调；以及5)在环境室以及在对二甲苯污染场地进行现场试验。研究成果，包括知识、工具和设备，将有助于保护人口以及淡水和土壤资源。一批重要的HQP将接受培训并加入到急需现场补救的领域的工作队伍中。

Petroleum contamination is present to a depth of 12-15 m along the St-Lawrence River. Of various petroleum hydrocarbons present in this contamination, p-xylene is the most prevalent, its concentration can reach more than 10 000 mg/kg in soil, and it can also be observed as an immiscible phase (pure phase). In fact, decontamination of this soil is a challenge as one must bring down the water table to the proximity of the St-Lawrence River (due to high permeability). Due to its physico-chemical properties (i.e. density, volatility, etc.), common methods, such as the hydrogen peroxide or heating treatment, are not adequate to remove the p-xylene in contaminated soils. Hence, an alternative strategy, using effective and unique biosurfactant-enzyme mixes, is needed to efficiently address the p-xylene bio-decontamination. The proposed project is based on the hypothesis that the rhamnolipids as biosurfactants can help form micelles which can be further acted upon by enzymes to bring about the biodegradation. This hypothesis has been tested in our laboratory and we observed that the biosurfactant-enzyme conglomerate can help degrade recalcitrant compounds, such as p-xylene. However, research is still required to comprehend the details on kinetics, interaction of biosurfactants and enzymes and their behaviour in field studies. Hence, the specific objectives of the proposal comprise: 1) selection and production of copious amounts of enzymes at the laboratory scale; 2) Demonstration of rhamnolipids production at the pilot scale; 3) caged formulations of biosurfactants and enzymes; 4) laboratory testing of the biosurfactant-enzyme mixes in columns, kinetic studies and fine tuning of the formulations; and 5) Application of this formulation in an environmental chamber as well as field tests on p-xylene contaminated sites. The research outputs, including knowledge, tools and devices, will assist in the protection of populations, and fresh water and soil resources. An important number of HQP will be trained and join the workforce in the critically needing area of site remediation.