(67c) Interaction of Micro- and Nano-Plastics with Marine Bacteria – What’s Happening Under the Tip of the ‘Plastic-Berg’?

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. By 2050, the weight of plastics in the ocean will exceed the weight of all marine organisms. This is a highly concerning statistic since plastics can have a half-life of several hundred years. Through ocean action, light and wind exposure these plastic pieces 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. There has been extensive publicity due to images of plastic material floating in large patches in the ocean and in fresh water. Since the densities of many commercial plastics (including plastic from natural sources, and those considered biodegradable) are larger than that of water, these materials do not stay on the surface, and sediment deeper into the water column - what is visible is only the tip of the ‘plastic-berg’. There are 14 million tons of microplastics on the ocean floor. There they not only encounter fish, but also ubiquitous marine cyanobacteria (CB) that are a critical part of the aqueous ecosystem. We use atomic force microscopy, Raman spectroscopy, and scanning electron microscopy to investigate the physical interaction between one of the most predominant seawater cyanobacteria (Synechococcus elongatus PCC 7002) and different plastics. Our results indicate a strong sensitivity to the plastic chemistry, size, surface topology and growth stage of bacteria. The physical, biological, and chemical response of the bacteria to these anthropogenic stressors will impact the fate of both the bacteria as well as the plastic contaminants in ocean water.