Discovery of naturally produced bioemulsifiers to remediate the next oil spill

原油事故，无论是在陆地上还是在海洋中，都会造成毁灭性的环境后果，特别是在污染敏感的栖息地。1989年阿拉斯加发生的埃克森-瓦尔迪兹号事故和2010年墨西哥湾发生的深水地平线号事故产生的大量石油被冲上岸，埋在海岸线沉积物中，在那里存留了几十年。微生物首先对环境污染做出反应，并处理进入环境的大部分油。然而，石油的生物降解可能极其缓慢，因此，石油最终下沉，然后被埋在沉积物中。埋藏的和有害的多环芳烃与油相关，然后在风暴事件中释放到地面，造成进一步的环境破坏。常见的石油泄漏应急响应策略是使用化学分散剂来促进石油的分散和溶解。然而，这些化学物质对环境中降解石油的微生物有很高的毒性。因此，需要新产品。该项目的总体目标是开发新的环保型分散剂、表面活性剂和乳化剂，以修复未来的石油泄漏。为了实现这一目标，研究小组将研究深水地平线漏油事件后发现的海岸细菌产生的天然乳化剂，然后测试有效的原油降解剂。该项目的成功完成将通过鉴定环境友好和有效的原油降解乳化剂来造福社会。通过对学生的教育和培训，包括对佐治亚理工学院的两名研究生的指导，将为社会带来更多的好处。石油泄漏需要数百万升的化学分散剂来帮助修复损害。对环境无害且有效的乳化剂和表面活性剂需要在以前禁止使用化学分散剂的情况下解决石油泄漏问题。该研究小组最近报道了一种新细菌的宏基因组引导分离，暂时命名为Candidatus Macondimonas重氮养菌，它代表了一个系统发育上狭窄的以前未被表征的原油降解菌群。这些微生物在世界各地沿海海洋生态系统的受油沉积物中含量很高，通常占微生物群落总数的30%，而在邻近的未受污染的样品中含量较低。自然生态系统中的这种高丰度表明，这些微生物具有不同寻常的生理能力，当暴露于石油污染时，它们比其他微生物具有优势。重氮营养菌基因组的生物信息学注释揭示了几个新的生物合成簇，预计这些簇可以生产基于脂质的生物乳化剂和表面活性剂。该项目的总体目标是鉴定和表征这些新的生物乳化剂，并测试它们加速原油生物降解的能力。新兴的生物修复技术将填补溢油相关灾害修复技术的空白。这些生物乳化剂也可能在提高自然栖息地的石油采收率以及在洗涤剂工业中作为氯化溶剂的替代品中找到应用。因此，由此产生的生物乳化剂和技术的广泛影响将影响多个科学和工程学科，并找到几个实际的生物技术应用。学生将在尖端宏基因组学和生物信息学与生物勘探，化学和工程的界面进行培训。从教育活动中获得的经验将在美国微生物学会主要的本科教育会议和墨西哥湾研究所年度会议期间与来自本科和社区学院的教员举行的讲习班上分享。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。

Crude oil accidents, either on land or in the ocean, have devastating environmental consequences, especially in pollution-sensitive habitats. Large amounts of oil from the Exxon-Valdez accident in 1989 in Alaska and the Deepwater Horizon accident in 2010 in the Gulf of Mexico washed up and were buried in shoreline sediments where they have persisted for decades. Microorganisms are the first to respond to environmental contamination and process most of the oil that enters the environment. However, oil biodegradation may be extremely slow and, as a result, oil ends up sinking and then is buried in sediments. Buried and harmful polycyclic aromatic hydrocarbons associated with oils can then be released to the surface during storm events causing further environmental damage. The common emergency response strategy to oil spills is to apply chemical dispersants to facilitate oil dispersion and dissolution. However, such chemicals can have high toxicity to microbes that degrade oil in the environment. Thus, new products are needed. The overarching objective of this project is to develop new, environmentally friendly dispersants, surfactants, and emulsifiers to remediate future oil spills. To achieve this objective, the research team will study the natural emulsifiers produced by coastal bacteria that were discovered in the aftermath of the Deepwater Horizon oil spill and then test effective crude-oil degraders. The successful completion of this project will benefit society through the identification of environmentally friendly and effective emulsifiers for crude-oil degradation. Additional benefits to society will be achieved through student education and training including the mentoring of two graduate students at Georgia Tech.Oil spills require millions of liters of chemical dispersants to help remediate damage. Environmentally benign and effective emulsifiers and surfactants are needed to address oil spills where the use of previous chemical dispersants have been banned. The research team has recently reported the metagenome-guided isolation of a novel bacterium, provisionally named Candidatus Macondimonas diazotrophica, that represents a phylogenetically narrow group of previously uncharacterized, crude-oil degraders. These microorganisms are highly abundant in oiled sediments of coastal marine ecosystems across the world, often comprising up to ~30% of the total microbial community, while being low abundance in adjacent, non-contaminated samples. This high abundance in a natural ecosystem suggests unusual physiological capabilities in these microorganisms that confer advantage over other microbes when exposed to oil contamination. The bioinformatic annotation of the Ca. M. diazotrophica genome has revealed several novel biosynthetic clusters that are predicted to produce lipid-based bioemulsifiers and surfactants. The overall goal of this project is to identify and characterize these new bioemulsifiers and test their ability to speed up crude oil biodegradation. The emerging bioremediation technologies will fill a gap in remediation techniques for oil spill-related disasters. These bioemulsifiers are also likely to find applications in enhanced oil recovery from natural habitats as well as in the detergent industry as a replacement for chlorinated solvents. Hence, the broader impacts of the resulting bioemulsifiers and technologies will affect multiple science and engineering disciplines and find several practical biotechnological applications. Students will be trained at the interface of cutting-edge metagenomics and bioinformatics with bioprospecting, chemistry, and engineering. The experience gained from the educational activities will be shared in a workshop with faculty from undergraduate and community colleges during the major undergraduate education conference of the American Society for Microbiology and at the Gulf of Mexico Research Institute annual conference.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.