Juarez study of bacterial growth on oil droplets could improve oil spill mitigation


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Gabriel Juarez
Gabriel Juarez
Assistant Professor Gabriel Juarez was awarded a grant from the Prince William Sound Oil Spill Recovery Institute (OSRI). Funding will support Juarez’s graduate student, Vincent Hickl, for a two-year research project on the effect of bacterial growth on the transport and fate of spilled oil droplets through experiments in microfluidic devices. 

One aspect of the Juarez Research Group is to study the impact of marine oil spills on society and marine ecosystems by optimizing bioremediation strategies based on fundamentally understanding the remarkable natural ability of marine bacteria to degrade hydrocarbons. Their project, “Bacterial Growth on Oil Transport,” targets the underlying physicochemical mechanisms between bacteria and individual oil droplets. 

Traditional biodegradation studies utilize the bulk sampling of liters of seawater at discrete time intervals from marine locations or laboratory batch reactors. While these macroscale approaches are important for assessing the biogeochemical state of the environment, they are not designed to analyze and understand the underlying physicochemical mechanisms that control transport and biodegradation in marine waters.

Juarez’s microscale approach will address this shortcoming by controlling the microenvironment with microfluidic devices while closely observing bacteria dynamics via microscopy. Insights regarding micro-scale processes of how bacteria physically attach to and colonize individual oil droplets will aid in understanding the transport of hydrocarbon pollutants in the ocean and establishing a quantitative mechanistic framework that will improve environmental-scale contingency planning. The group’s experiments will build upon current, ongoing research that focuses on the physical attachment of bacteria to stationary oil droplets through the use of optical microscopy with novel microfluidic devices. Direct observations in microfluidic devices combined with mechanistic models enables analysis of an array of environmentally relevant parameters, such as droplet size distribution, crude oil composition, oil-degrading bacteria concentration, biofilm growth, and community composition. 

Juarez and Hickl hope to gain a better understanding of the impact of bacterial growth on oil droplet size and morphology, which would help guide oil spill mitigation strategies by informing decision-makers with fundamental and sound scientific results.

“Our work will provide the first visual description of microbial attachment and growth rates on the surface of oil droplets in a variety of sizes at unprecedented temporal resolution,” said Juarez. “This will establish a direct link between physical processes at the microscale and the oil transport observed in situ following oil spills.”

The OSRI, based in Alaska, was established after the historic 1989 Exxon Valdez oil spill. Its mission is to identify and develop the best techniques, equipment, and materials for responding to oil spills in Arctic environments.

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This story was published June 29, 2020.