In Situ Investigation of Plastic-Associated Bacterial Communities in a Freshwater Lake of Hungary

Despite the great benefits of plastics in different aspects of life and due to the increase in plastic production and use, plastic wastes are becoming a major environmental concern. It is well known that inappropriate use and disposal lead to the accumulation of plastic litter in different aquatic environments. Microbial biofilm is able to develop on the surface of plastics (plastisphere) in aquatic environments over time. The aim of this study was to describe the bacterial communities associated with plastics in freshwater. Thus, in our first test, a total of six self-designed plastic colonizers were submerged under the surface of the water in Vacszentlaszlo lake, located in central Hungary, for a period of 3 months. Two plastic colonizers were cultivated monthly. Associated microbial communities were then analyzed as follows: (a) bacterial communities were studied by amplicon sequencing and (b) culturable bacteria were isolated from plastic surfaces and identified by 16S rRNA gene sequencing. Coinciding with these analyses of plastic colonizing communities, surface water samples from the lake were also taken, and in a second test, other materials (eg. wood, glass) associated bacterial communities were also investigated with the same methods. Amplicon sequencing showed notable differences between the plastic and other materials colonizing, and lake waterborne microbial community composition. Using the LB agar, no novel species were found; however, several known pathogenic species were identified. The self-designed plastic colonizer was successfully used during the winter over a 3-month period, suggesting that it could be an appropriate method of choice to study microplastic-associated microbes for longer periods and in variable environmental conditions.