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

圣劳伦斯河沿岸有12-15米深的石油污染。在这种污染中存在的各种石油烃中，对二甲苯是最普遍的，其浓度在土壤中可达到10,000 mg/kg以上，并且也可以观察到它为不混相（纯相）。事实上，净化土壤是一个挑战，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）。由于其物理化学性质（即密度，挥发性等），常见的方法，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净化问题。提出的项目是基于假设鼠李糖脂作为生物表面活性剂可以帮助形成胶束，而胶束可以进一步被酶作用以实现生物降解。这个假设已经在我们的实验室进行了测试，我们观察到生物表面活性剂-酶砾岩可以帮助降解顽固性化合物，如对二甲苯。然而，在实地研究中，对生物表面活性剂和酶的动力学、相互作用及其行为的细节仍需深入了解。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)鼠李糖脂中试生产示范；3)笼型生物表面活性剂和酶制剂；4)生物表面活性剂-酶混合柱的实验室测试，动力学研究和配方的微调；5)本配方在环境箱中的应用以及对二甲苯污染场地的现场试验。研究成果，包括知识、工具和设备，将有助于保护人口、淡水和土壤资源。一批重要的HQP人员将接受培训，并在急需的场地修复领域加入工作队伍。

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.