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

沿圣劳伦斯河沿着12-15米深处存在石油污染。在污染物中存在的各种石油烃中，对二甲苯是最普遍的，其在土壤中的浓度可达10 000 mg/kg以上，并且还可以观察到不混溶相（纯相）。事实上，这种土壤的净化是一个挑战，因为必须将地下水位降低到圣劳伦斯河附近（由于渗透性高）。由于其物理化学性质（即密度、挥发性等），常用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，需要使用有效且独特的生物表面活性剂-酶混合物的替代策略来有效地解决对二甲苯生物去污问题。该项目基于这样的假设，即作为生物表面活性剂的鼠李糖脂可以帮助形成胶束，该胶束可以进一步被酶作用以实现生物降解。这一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-酶聚集体可以帮助降解难降解的化合物，如对二甲苯。然而，研究仍然需要了解动力学的细节，生物表面活性剂和酶的相互作用及其在现场研究中的行为。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）在中试规模上证明鼠李糖脂的生产; 3）生物表面活性剂和酶的笼状制剂; 4）在柱中生物表面活性剂-酶混合物的实验室测试、动力学研究和制剂的微调;和5）该制剂在环境室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、工具和装置，将有助于保护人口、淡水和土壤资源。大量的HQP将接受培训，并加入急需现场修复的领域。

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.