ERASE-PFAS: Microbial electrochemical defluorination of PFAS using bioaugmented Acidmicrobium sp. Strain A6

Per和多氟烷基物质（PFAS）是令人关注的新兴污染物，因为它们无处不在，与包括癌症在内的多种健康问题有关。PFAS非常稳定，最受关注的PFAS被认为是不可生物降解的。这种稳定性使这些化合物被称为“永远的化学物质”。最近，在酸性富铁土壤中常见的酸性微生物（A6）已被证明可以降解PFAS。A6利用氨作为能量与固相氧化铁反应。虽然氧化铁在土壤中很常见，但将它们添加到生物反应器中以控制A6的生长是具有挑战性的。为了解决这些问题，开发了一种以铁为阳极的特殊生物电化学反应器。该项目的目标是获得对A6如何降解PFAS的基本理解。这将通过使用特制的生物电化学反应器在不同的PFAS和操作条件下测试A6来实现，以了解PFAS的生物降解机制。这项研究的成功完成将允许A6的快速生长，以便随后将A6添加（“生物增强”）到受污染的土壤中，以现场处理PFAS，或通过在生物反应器中直接处理PFAS污染的水。该项目将在PFAS治疗的新领域对研究生、本科生和STEM高中学生进行暑期实习。研究结果将在科学期刊和会议上传播，以促进知识的发展。推广工作的重点是通过与一家公司合作，实施一个示范项目，在现实世界的应用中进行测试，从而促进对这种新型治疗技术的接受。酸性微生物sp.菌株A6 （A6）是一种新的自养革兰氏阳性细菌，在氧化铵的同时还能还原铁。A6能够除氟全氟化合物，包括全氟化合物，如全氟辛酸和全氟辛烷磺酸。A6的基因组包含脱卤酶基因，包括还原性脱卤酶同源物和氟乙酸脱卤酶同源物，它们都在PFAS脱氟时表达。A6对铁的高需求使得在传统的生物反应器中长时间培养这种菌株具有挑战性。幸运的是，A6是电致的，可以在没有铁的微生物电解细胞中生长，在那里它也能够去氟化PFOA。这项新颖的研究首先集中在了解A6在生物电化学系统中生长的机制。将使用纯培养物和富集培养物检查PFAS除氟，同时跟踪基因表达和降解中间体。生物反应器的结果将与分批培养的结果结合起来，并与酶学家单独合作，以获得对A6对PFAS除氟作用机制的新见解。该项目将培养一名博士生，并使来自多个实验室的学生密切合作，以增加跨学科合作。暑期工程和高中实习生将被招募到实验室工作，以增加STEM培训。与一个工业伙伴的合作将实施A6生物增强试验示范，以降解工业废物中的PFAS，以促进在补救领域实施这些发现。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Per and polyfluorinated alkyl substances (PFAS) are emerging contaminants of concern because they are ubiquitous and have been linked to multiple health problems, including cancer. PFAS are extremely stable, and those of most concern have been considered non-biodegradable. This stability has led to these compounds being dubbed “forever chemicals.” Recently, the bacterium Acidimicrobium (A6) commonly found in acidic iron rich soils has been shown to degrade PFAS. A6 uses ammonia for energy by reaction with solid-phase iron oxides. Although iron oxides are common in soils, adding them to bioreactors for the controlled growth of A6 is challenging. To address these challenges, a special bioelectrochemical reactor was developed with iron serving as the anode. The goal of this project is to gain a fundamental understanding of how A6 degrades PFAS. This will be achieved through testing A6 with various PFAS and operational conditions using the specially formulated bioelectrochemical reactors to understand the mechanisms of PFAS biodegradation. Successful completion of this research will allow the rapid growth of A6 for subsequent addition (“bioaugmentation”) of A6 into contaminated soils to treat PFAS on site, or through direct treatment of PFAS-contaminated water in the bioreactors. This project will train graduate students, undergraduate students, and involve STEM high school students during summer internships in the novel field of PFAS treatment. Results will be disseminated in scientific journals and conferences to advance knowledge. Outreach efforts are focused on advancing acceptance of this novel treatment technology through collaboration with a company to implement a demonstration project for testing in real world applications. Acidimicrobium sp. Strain A6 (A6) is a novel autotrophic Gram-positive bacterium that oxidizes ammonium while reducing iron. A6 is capable of defluorinating PFAS, including perfluorinated compounds such as PFOA and PFOS. The genome of A6 contains dehalogenase genes, including a reductive dehalogenase homolog and a fluoroacetate dehalogenase homolog that are both expressed when PFAS are defluorinated. The high demand of A6 for ferric iron makes it challenging to grow this strain in traditional bioreactors for extended periods of time. Fortunately, A6 is electrogenic and can grow in the absence of iron in microbial electrolysis cells, where it is also able to defluorinate PFOA. This novel research focuses first on understanding the mechanisms by which A6 grows in bioelectrochemical systems. PFAS defluorination will be examined using both pure and enrichment cultures while tracking gene expression and degradation intermediates. Bioreactor results will be combined with results from batch incubations, and a separate collaboration with enzymologists to gain new insights into the mechanisms of PFAS defluorination by A6. The project will train a PhD student and result in close collaboration between students from multiple laboratories to increase cross disciplinary collaboration. Summer engineering and high school interns will be recruited to work in the laboratories to increase STEM training. A collaboration with an industrial partner will implement a pilot demonstration of A6 bioaugmentation to degrade PFAS in industrial waste to facilitate implementation of these findings in the remediation field.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.