Microbial Ecotoxicology of Marine Plastic Debris: A Review on Colonization and Biodegradation by the “Plastisphere”

Abstract

Over the last decades, it has become clear that plastic pollution presents a global societal and environmental challenge given its increasing presence in the oceans. A growing literature has focused on the microbial life growing on the surfaces of these pollutants called the “plastisphere,” but the general concepts of microbial ecotoxicology have only rarely been integrated. Microbial ecotoxicology deals with (i) the impact of pollutants on microbial communities and inversely (ii) how much microbes can influence their biodegradation. The goal of this review is to enlighten the growing literature of the last 15 years on microbial ecotoxicology related to plastic pollution in the oceans. First, we focus on the impact of plastic on marine microbial life and on the various functions it ensures in the ecosystems. In this part, we also discuss the driving factors influencing biofilm development on plastic surfaces and the potential role of plastic debris as vector for dispersal of harmful pathogen species. Second, we give a critical view of the extent to which marine microorganisms can participate in the decomposition of plastic in the oceans and of the relevance of current standard tests for plastic biodegradability at sea. We highlight some examples of metabolic pathways of polymer biodegradation. We conclude with several questions regarding gaps in current knowledge of plastic biodegradation by marine microorganisms and the identification of possible directions for future research.

Microbial colonization of microplastics in the Caribbean Sea

“…Using light microscopy, however, Eich et al () found certain diatom taxa to specifically colonize HDPE or a biopolymer‐polyethylene terephthalate (PETE) (biodegradable) in the Mediterranean Sea. These observations support the complex interplay of the factors involved in shaping plastisphere communities (reviewed by Jacquin et al ), and the importance of understanding the colonization of new plastics in the environment over time.…”

Microbial Colonization in Marine Environments: Overview of Current Knowledge and Emerging Research Topics

“…According to a recent review by Jacquin et al [85], plastisphere communities found in the sub-surface are dominated by photoautotrophic bacteria such as cyanobacteria with the genera Phormidium and Rivularia, while the core microbiome of the seafloor and subsurface plastisphere seems to share some taxa, such as Bacteroidetes (Flavobacteriaceae) and Proteobacteria (Rhodobacteraceae and Alcanivoraceae) [42,[86][87][88]. Plastic-attached bacteria were dominated by alphaand gamma-Proteobacteria, while seawater bacteria were dominated by alpha-Proteobacteria (mainly Pelagibacter sp.)…”

Bio-upcycling of polyethylene terephthalate

“…For obvious reasons, the biodegradation of these recalcitrant plastics are exciting discoveries that give hope for the natural bioremediation of sites contaminated with plastic waste in the environment, although plastic degradation in the ocean seems to be slow at best and the anthropogenic dissemination of new plastic pollution likely far exceeds its decay 18 . Notably, this biodegradation also offers a tremendous opportunity for waste treatment: To biotechnologically upcycle plastic waste to valuable products such as bioplastics.…”