RUI: Reducing Permeability in Sands Using Biofilm-Forming Bacteria and Quorum Sensing Inhibitors to Create Uniform Growth

水在土壤中的流动(渗漏)可能会导致大坝和堤坝坍塌，这可能是昂贵的维修费用，对基础设施造成广泛的破坏，甚至可能造成生命损失。传统的减少渗漏的方法可能成本高昂，并造成环境问题。初步工作表明，使用生物膜形成细菌来减少渗漏是可行的。形成生物膜的细菌分泌一种粘性物质，将细菌连接在一起，将细菌附着在固体表面，并阻止水通过土壤流动。然而，渗漏的减少只发生在靠近细菌营养来源的地方，而距离来源更远(超过5厘米)的渗漏并没有显著减少。如果使用细菌形成生物膜是减少渗漏的可行方法，则需要在至少一米的距离内均匀减少渗漏，并降低上述故障类型的可能性。该项目将确定是否可以使用群体感应抑制剂(一种防止细菌形成生物膜的化学物质)来控制生物膜形成的位置和时间，以便生物膜在一米长的沙柱上均匀发展。如果成功，进一步的研究将着眼于将这一方法应用于实地应用。此外，这笔赠款将支持拉斐特学院(LC)与国家科学基金会工程研究中心(ERCs)之一--新的生物中介和生物启发岩土技术中心(CBBG)--之间的合作。加州大学教职员工(项目PIS)和CBBG之间的研究伙伴关系将创造一种信息交流，使PIS能够与CBBG合作开发他们的研究计划，并将向这一新的跨学科研究领域引入至少6名本科生。由于LC的女学生比例很高，这项拨款预计将扩大对这一代表不足的群体的研究参与。这项研究将开发通过使用群体感应抑制剂以及对流速和养分的操纵来在沙子中均匀生长细菌生物膜的方法。最初，荧光假单胞菌，一种已知的生物被膜前体物，将被引入含有无菌沙子的柱中。控制含有营养素的水和群体感应抑制剂呋喃酮56的浓度和时间将被用于在这些土壤中创建均匀分布的细菌生物膜。呋喃酮56是一种已知的抑制生物膜形成的卤代化合物。一旦建立了在这些条件下开发均匀生物膜分布的方案，就将使用非灭菌沙子构建色谱柱。将使用对营养物质和群体感应抑制剂的类似操作来调查所开发的方法是否能够刺激本地生物膜形成细菌创建均匀分布的生物膜。最终的测试设置将确认，本地细菌生物膜可以沿一米长的土柱均匀分布。通过LC和CBBG之间的合作，这笔赠款还将支持一所严格的本科院校的跨学科教员团队进行创新研究，并为本科生提供强有力的指导和研究体验。LC和CBBG的教职员工之间的研究伙伴关系将创造一种信息交流，使LC的教职员工能够与CBBG合作开展他们的研究，并将为这一新兴的跨学科研究领域引入至少6名本科生。

The movement of water through soil (seepage) can cause dams and levees to fail, which may be expensive to repair, cause extensive damage to infrastructure, and possibly the loss of life. Traditional methods to reduce seepage can be cost-prohibitive and create environmental concerns. Preliminary work has shown the feasibility of using biofilm-forming bacteria to reduce seepage. Biofilm-forming bacteria secrete a sticky material that connects the bacteria together, attaches the bacteria to solid surfaces, and blocks the flow of water through the soil. However, the reduction in seepage only occurred close to the bacteria's nutrient source and seepage further from the source (more than five centimeters) was not significantly reduced. Uniform reduction of seepage across a distance of at least one meter will be needed if using bacteria to form biofilms is to be a feasible method to reduce seepage and the likelihood of the types of failures listed above. This project will determine whether a quorum sensing inhibitor (a chemical that prevents bacteria from forming a biofilm) can be used to control the location and timing of biofilm formation so that the biofilm develops uniformly across the length of a one-meter column of sand. If successful, further research would look at the application of this methodology to field applications. In addition, this grant will support a partnership between Lafayette College (LC) and one of the National Science Foundation's Engineering Research Centers (ERCs)--the new Center for Bio-mediated & Bio-inspired Geotechnics (CBBG). The research partnership between faculty at LC (the project PIs) and the CBBG will create an exchange of information that will allow the PIs to develop their research programs in cooperation with the CBBG, and will introduce a minimum of six undergraduate students to this new interdisciplinary field of research. Because of high percentages of women students at LC, this grant is anticipated to broaden research participation with respect to this underrepresented group.This research will develop methods to create a uniform growth of bacterial biofilm in sand by using quorum sensing inhibitors and the manipulation of flow rates and nutrients. Initially, Pseudomonas fluorescens, a known biofilm former, will be introduced to columns containing sterile sand. The manipulation of the concentration and timing of water containing nutrients and a quorum sensing inhibitor, Furanone 56--a halogenated compound known to inhibit biofilm formation, will be used to create a uniform distribution of bacterial biofilm in these soils. Once a protocol is established for the development of a uniform biofilm distribution under these conditions, columns will be constructed using non-sterile sand. Similar manipulation of the nutrient and quorum sensing inhibitor will be used to investigate whether the approach developed can stimulate native biofilm-forming bacteria to create a uniform distribution of biofilm. A final testing setup will confirm that native bacterial biofilm can be uniformly distributed along a one-meter soil column. Through a partnership between LC and the CBBG, this grant will also support innovative research by an interdisciplinary team of faculty at a strictly undergraduate institution and provide robust mentoring and research experiences for undergraduate students. The research partnership between faculty at LC and the CBBG will create an exchange of information that will allow the faculty at LC to develop their research in cooperation with the CBBG and will introduce a minimum of six undergraduate students to this newly developing interdisciplinary field of research.