Mentor: Arijit Bose (University of Rhode Island)

Project Location

University of Rhode Island – Kingston

Project Description

Overview
Plastics are ubiquitous, the worldwide annual consumption is approximately 300 million tons. Most of these plastics are not recycled, and they eventually make their way into the ocean. About 150 million tons of plastic are in the world’s oceans currently, and 8 million additional tons of plastics are dumped into the ocean each year. Sources include packaging, straws, bags, soaps, cosmetics, utensils, and cups. By 2050, the weight of plastics in the ocean will exceed the weight of all marine organisms. The Narragansett Bay is a microcosm of what is happening to ocean waters all over the world. Through ocean action, light and wind exposure these plastics eventually break up into millimeter- and lower-sized objects, known as microplastics. The role of this anthropogenic stressor on marine life must be understood for remediation strategies as well as for policy decisions. While images of plastic material floating in large patches in the ocean and in fresh water have received wide publicity, what is visible is only the tip of the ‘plastic-berg’. The densities of many commercial plastics are larger than that of water. These materials sink deeper into the water column. About 14 million tons of microplastics are estimated to be on the ocean floor. These plastics not only encounter fish, but also marine cyanobacteria (CB) that reside near the ocean surface. Cyanobacteria are ubiquitous and are a critical part of the aqueous ecosystem because they help maintain the oxygen levels in the ocean. Very little is currently known about the fate of plastics or these bacteria after exposure. Recent collaborative results from our laboratories using spherical polystyrene (PSS) and polyethylene terephthalate (PET) nanoparticles and microparticles (Langmuir, 36, 3692-3699 (2020); PLoS ONE, 15, e0232745 (2020)) revealed that cyanobacteria can attach to these plastics, and for micron sized PET, they overexpress genes responsible for making plastic-specific degrading enzymes. Thus, the bacteria may be partially mitigating the deleterious effect of plastics in the ocean.

Planned experiments
We will expose plastic of different shapes, size and chemistry to marine cyanobacteria. Attachment of the cyanobacteria to the plastic can only occur if there is a net attractive interaction between the two. We will use atomic force microscopy (AFM) to monitor the magnitude and sign of the force between the plastic and bacteria (force -distance measurement) in saline water. We will do this using two complementary techniques (a) bacterium loaded on an AFM tip interacting with flat plastic sheets and (b) plastic bead on an AFM tip interacting with a layer of bacteria immobilized on a glass slide. Two SURF students will work on these experiments, one for each technique. The results from this work will provide important insights on the fate of plastic pollutants in the ocean.

This project involves:

• lab work

Available for SURF Flex?

Yes

Required/preferred skills

Motivation, desire to learn sophisticated experimental techniques.

2022