The Plastisphere: Prokaryotic Communities on a Plastic Bag in the Mediterranean Sea

Plastic pollution has become an integral part of our environment. The frequent use of plastic and its low recycling rates on land led to the introduction of millions of tons of new plastic debris into the oceans every year. Plastic is not easily degraded and remains in the water circulation for long periods of time where it is being colonized by communities of microorganisms commonly termed "plastisphere”. The plastisphere is dominated by prokaryotes of which some have been adapted to live on plastic and some can even metabolize it. This study aimed to characterize plastic microbiome and its dynamic in the Mediterranean Sea. Polyethylene (PE) plastic bags were placed in the marina and in open water in Herzeliya, Israel. eDNA was extracted from the water and the bags after one month at sea. 16s rRNA gene marker was amplified, followed by MinION nanopore high-throughput sequencing and bioinformatic identification of the prokaryotic taxa based on comparison of the reads to the Silva and NCBI databases. Scanning electron microscopy, biofilm cover, and hydrophobicity were estimated to better understand the plastisphere structure and development. Our initial results show massive colonization of bacteria from diverse taxa on the plastic. The plastic samples were different in taxa composition than the water samples. The plastic samples were dominated by Proteobacteria including several potential petroleum-degrader species whereas the water samples were dominated by Cyanobacteria. Taken together our results suggest that the plastic serves as a separated ecological niche for marine microorganisms.