Impacts of Biofilm Formation on the Fate and Potential Effects of Microplastic in the Aquatic Environment

TLDR

Microplastic (<5 mm) persists in aquatic environments and can adversely affect biota, yet most studies use virgin, spherical particles while real surfaces are colonized by biofilms whose influence on microplastic fate and effects remains poorly understood. This review seeks to elucidate how early microbial colonization on plastic surfaces changes microplastic fate and impacts, and to emphasize the need for laboratory tests that simulate field conditions with biofilm dynamics. The authors examine the physical interactions between biofilms and microplastic, focusing on how colonization alters weathering, vertical transport, sorption, and contaminant release. Evidence shows that biofilm–plastic interactions can modify microplastic physical properties, thereby affecting their environmental fate and potential ecological consequences.

Abstract

In the aquatic environment, microplastic (MP; <5 mm) is a cause of concern because of its persistence and potential adverse effects on biota. Studies of microlitter impacts are mostly based on virgin and spherical polymer particles as model MP. However, in pelagic and benthic environments, surfaces are always colonized by microorganisms forming so-called biofilms. The influence of such biofilms on the fate and potential effects of MP is not understood well. Here, we review the physical interactions of early microbial colonization on plastic surfaces and their reciprocal influence on the weathering processes and vertical transport as well as sorption and release of contaminants by MP. Possible ecological consequences of biofilm formation on MP, such as trophic transfer of MP particles and potential adverse effects of MP, are virtually unknown. However, evidence is accumulating that the biofilm−plastic interactions have the capacity to influence the fate and impacts of MP by modifying the physical properties of the particles. There is an urgent research need to better understand these interactions and increase the ecological relevance of current laboratory testing by simulating field conditions in which microbial life is a key driver of biogeochemical processes.