Oceans are filled with plastic, which provides an ideal environment for bacterial growth. A critical component of evaluating the ecological effects and future of plastics in the marine environment is understanding biofouling mechanisms. In this study, we examined the various stages of plastic colonisation of polyester, Poly(3-Hydroxybutyrate-Co-3-Hydroxyvalerate) (PHBV), and polyolefin-based plastics, including standard low-density Polyethylene (PE), additivities of PE with pro-oxidant (OXO), and Artificially Aged OXO (AA-OXO). We used a variety of methods, some of which were used for the first time on plastics, to combine measurements of physical surface properties of polymers (hydrophobicity and roughness) with biofilm microbiological characterisation (cell counts, taxonomic composition, and heterotrophic activity). We were able to characterise the subsequent stages of primo-colonization, growth, and maturation of the biofilms thanks to our experimental setup using aquariums with naturally circulating seawater over a period of 6 weeks. The biodegradable AA-OXO and PHBV polymer types showed increased colonisation by active and particular bacteria compared to non-biodegradable polymers, which was one of the trends we highlighted between polymer types with various surface qualities and compositions (PE and OXO). The three stages of colonisation resulted in a succession of the bacterial population, with hydrocarbon clastic bacteria being extremely prevalent on all types of plastic. This study presents original data that offers fresh perspectives on how marine microorganisms colonise nonbiodegradable and biodegradable plastics.
