Microplastic surface properties affect bacterial colonization in freshwater

Abstract

Microplastics are a global concern in aquatic ecology and are readily colonized by bacteria in the environment. There is a lack of information on bacterial colonization of eroded and un‐eroded microplastics in freshwater. In this study, six types of microplastics were incubated for 8 weeks in microcosms with water from Lake Erie. Microcosms were inoculated with one of three species: Acinetobacter (A.) calcoaceticus, Burkholderia (B.) cepacia, and Escherichia (E.) coli. These bacterial species are ubiquitous in water bodies associated with human populations. Bacterial surface coverage was determined using electron and fluorescent microscopy. Quantifications of EPS and surface roughness were performed by confocal microscopy and measuring contact angles (θw) of water droplets on microplastics, respectively. Analyses revealed surface coverage differed among bacterial species and plastic types after 8 weeks. As the study progressed, E. coli remained the most abundant while A. calcoaceticus gradually decreased on most surfaces. Analyses of microcosms revealed polypropylene disks had lower bacterial abundance. Conversely, eroded polypropylene disks had highest bacterial abundance, indicating importance of surface roughness (lower θw values) and surface physicochemical properties of microplastics in bacterial colonization. Our results demonstrated that bacterial colonization of microplastics is affected by both the physicochemical properties of microplastics and the physiological properties of colonizing bacteria.

Towards an ecology of soil microplastics

“…Allochthonous microplastics introduced to a soil may well be colonized by microbes, as is common in aquatic and sediment systems (Harrison, Schratzberger, Sapp, & Osborn, ; Hossain, ; Kettner et al, ; McCormick et al, ; Phuong et al, ). Polyethylene microfilms from the breakdown of agricultural film were found to host microbial communities unique from those of soil, litter and macroplastic surfaces (Zhang et al, ), though the extent of this across other soils and microplastic types has yet to be determined.…”

“…Allochthonous microplastics introduced to a soil may well be colonized by microbes, as is common in aquatic and sediment systems (Harrison, Schratzberger, Sapp, & Osborn, 2014;Hossain, 2019;Kettner et al, 2017;McCormick et al, 2014;Phuong et al, 2016).…”

Biodeterioration of Untreated Polypropylene Microplastic Particles by Antarctic Bacteria

“…The addition of the repetitive presence of methyl side chains (-CH 3 ) in every unit also decreases the potential of PP to undergo degradation processes [21]. This structural feature of PP hinders the attachment of microbes on its surface, deters the production of biofilm (or biosurfactant), and decelerates the onset of degradation [22,23]. Due to this, several studies have been conducted in an attempt to accelerate the biodegradation rate of PP using supplements such as carbon-high starch [24] and bioplastic blends [25,26].…”

Laser beam scattering for the detection of flat, curved, smooth, and rough microplastics in water

“…Additionally, surface properties of plastics and MPs are indicative of the degradation process [7]. Surface roughness in addition to air pockets offers a platform for the adsorption of organic and inorganic contamination particles [8][9][10] that may have lower or higher gravity than that of the MP. Additionally, surface roughness has a consequence on the hydrodynamic properties of MPs, namely on the drifting of MPs over long distances [11].…”