The Terrestrial Plastisphere: Diversity and Polymer-Colonizing Potential of Plastic-Associated Microbial Communities in Soil

Abstract

The concept of a ‘plastisphere microbial community’ arose from research on aquatic plastic debris, while the effect of plastics on microbial communities in soils remains poorly understood. Therefore, we examined the inhabiting microbial communities of two plastic debris ecosystems with regard to their diversity and composition relative to plastic-free soils from the same area using 16S rRNA amplicon sequencing. Furthermore, we studied the plastic-colonizing potential of bacteria originating from both study sites as a measure of surface adhesion to UV-weathered polyethylene (PE) using high-magnification field emission scanning electron microscopy (FESEM). The high plastic content of the soils was associated with a reduced alpha diversity and a significantly different structure of the microbial communities. The presence of plastic debris in soils did not specifically enrich bacteria known to degrade plastic, as suggested by earlier studies, but rather shifted the microbial community towards highly abundant autotrophic bacteria potentially tolerant to hydrophobic environments and known to be important for biocrust formation. The bacterial inoculates from both sites formed dense biofilms on the surface and in micrometer-scale surface cracks of the UV-weathered PE chips after 100 days of in vitro incubation with visible threadlike EPS structures and cross-connections enabling surface adhesion. High-resolution FESEM imaging further indicates that the microbial colonization catalyzed some of the surface degradation of PE. In essence, this study suggests the concept of a ‘terrestrial plastisphere’ as a diverse consortium of microorganisms including autotrophs and other pioneering species paving the way for those members of the consortium that may eventually break down the plastic compounds.

Nocardioides alcanivorans sp. nov., a novel hexadecane-degrading species isolated from plastic waste

“…A set of microbial strains was isolated from plastic debris and plastic-polluted soil found on an abandoned landfill in the Potsdam-Mittelmark district of Brandenburg, north-eastern Germany (52° 02′ 58.8″ N 12° 39′ 34.8″ E). The research aimed at understanding this example of a terrestrial plastisphere as a distinct microbial habitat and the potential of such plastic-associated micro-organisms to degrade polyethylene [1], one of the most common plastic types found in the terrestrial environment. The microbial isolates were enriched in slurries prepared with plastic debris from the landfill and mineral salt medium (MSM; 0.1% (NH 4 )2SO 4 , 0.1% K 2 HPO 4 , 0.1% NaNO 3 , 0.1% KCl, 0.02% MgSO 4 and 0.01% yeast extract) containing cycloheximide (1% of 1 M) but no additional carbon source according to a protocol of Burd [2].…”

Fate of petroleum-based and plant-based teabags exposed to environmental soil conditions for one year

“…PLA teabags, in fact, remained intact in terms of weight and fibre density throughout the whole study. Furthermore, PLA teabags showed a slightly increased weight overtime, which could potentially be explained by a growing microbiota biofilm ( MacLean et al, 2021 ).…”

Paenalcaligenes niemegkensis sp. nov., a novel species of the family Alcaligenaceae isolated from plastic waste

“…In the frame of a study targeting the culture-dependent microbial diversity of the terrestrial plastisphere, a set of microbial strains was isolated from plastic debris and plastic-polluted soil found on an abandoned landfill close to the small city of Niemegk in the Potsdam-Mittelmark district of Brandenburg, north-eastern Germany (52° 02′ 58.8″ N, 12° 39′ 34.8″ E). The investigation aimed at understanding the terrestrial plastisphere as a distinct microbial habitat and the potential of such plastic-associated micro-organisms to degrade polyethylene [1], one of the most common plastic types found in the terrestrial environment. The microbial isolates were enriched in slurries prepared with plastic debris from the landfill and mineral salt medium (MSM; 0.1 % (NH 4 ) 2 SO 4 , 0.1 % K 2 HPO 4 , 0.1 % NaNO 3 , 0.1 % KCl, 0.02 % MgSO 4 and 0.01 % yeast extract) containing cycloheximide (0.01 M) but no additional carbon source, according to a protocol of Burd [2].…”