SRA

Plastic marine debris is a recent introduction to marine ecosystems resulting from the widespread use of polymers in consumer goods after World War II. The current global annual production of plastic is 245 million tonnes or 35 kg of plastic for each of the 7 billion humans on the planet, rivaling the combined biomass of all humans. Drifter buoys and physical oceanographic models demonstrate that surface particles passively migrate from the coastline to the central gyres in less than 60 days, illustrating how quickly human-generated debris can impact the ‘pristine’ gyre interiors, more than 1000 km from land. Plastic debris has been implicated as a vector for transportation of harmful algal species and persistent organic pollutants, and provides a substrate for microbes that moves between environments and lasts much longer than most natural floating substrates. Despite increases in plastic production no significant trend in plastic accumulation has been observed since 1985. Physical shearing and photodegradation are known mechanisms of plastic degradation, but microbial degradation has also been implicated. Unpublished data from our laboratories employing pyrotag amplicon sequencing targeting bacterial and eukaryotic small subunit ribosomal RNA gene sequences, together with Scanning Electron Microscopy (SEM) data are consistent with the notion that plastic debris harbors a unique association of microbes including members capable of degrading plastic. The term ‘Plastisphere’ describes this unique microbial community attached to and surrounding marine plastic debris and distinct from microbes in the surrounding seawater and on natural substrates such as macroalgae. This proposal will: (1) characterize diversity through amplicon sequencing and comparative -omics combined with SEM and confocal microscopy to investigate the microbial composition of the Plastisphere; (2) describe function of the Plastisphere taking a cultivation-independent environmental DNA gene expression approach, as well as a cultivation-based approach to interrogate environmental clones and microbial isolates for the ability to degrade hydrocarbons; and (3) determine key biological factors that control the fate of plastic debris in the upper water column.