Biofilms of Pseudomonas and Lysinibacillus Marine Strains on High-Density Polyethylene

Abstract

Environmental pollution by plastic debris is estimated on a scale of 100 million metric tons, a portion of which is fragmented into micro-and nanoplastics. These fragments are often colonized by bacterial species in marine environments, possibly contributing to the biodegradation of such materials. However, further investigations are necessary to determine the impact of abiotic polymer weathering on biofilm adhesion, as well as the specific biofilm formation strategies employed by marine isolates. Here, we evaluate deep-sea sediment bacterial isolates for biofilm adhesion, extracellular matrix production, and polymer degradation ability. Our study focuses on high-density polyethylene (HDPE) fragments for their high durability and environmental persistence, subjecting fragments to abiotic weathering prior to bacterial colonization. Marine isolates identified as Pseudomonas sp. and Lysinibacillus sp. exhibited decreasing biofilm formation on weathered HDPE, especially over the first 24 h of incubation. This effect was countered by increased extracellular matrix production, likely improving cell adhesion to surfaces roughened by abiotic degradation. These adhesion strategies were contrasted with a reference Pseudomonas aeruginosa strain, which displayed high levels of biofilm formation on non-weathered HDPE and lower extracellular matrix production over the first 24 h of incubation. Furthermore, our results suggest that an increase in biofilm biomass correlated with changes to HDPE structure, indicating that these strains have a potential for biodegradation of plastic fragments. Therefore, this work provides a detailed account of biofilm formation strategies and bacteria-plastic interactions that represent crucial steps in the biodegradation of plastic fragments in marine environments.

Structural and Functional Characteristics of Microplastic Associated Biofilms in Response to Temporal Dynamics and Polymer Types

“…As the biofilms developed (30 days), more living bacteria were observed together with the extracellular polymeric substances. This is consistent with the SEM images, indicating that these bacteria may devote part of their resources toward biofilm formation via production of extracellular polymeric substances, possibly at the cost of the colonization speed (Oliveira et al 2021).…”

“…The presence of the blanket like extracellular polymeric substances on-top of the bacteria colonizing the surface of PE at day 10 (top left of Fig. 2) indicates that these bacteria may have utilized the PE as the carbon and energy source to drive the biofilm formation (Oliveira et al 2021). The SEM results showed that polymer components and the time for the interaction of MPs and colonizing microbes could synergistically affect the morphological characteristics of the biofilms.…”

Plastic Degradation by Extremophilic Bacteria

“…and Lysinibacillus sp. showed biofilm-related potential for high density PE biodegradation even within a short, 24 h test interval [ 80 ]. These microorganisms produced increased extracellular matrixes that improve cell adhesion to plastic surface.…”

Biochemical features and early adhesion of marine Candida parapsilosis strains on high-density polyethylene

“…Microplastic pollution has reached nearly all ecosystems on the planet, including the seafloor (Kane et al, 2020). Microbial communities present in marine sediments interact with these plastic fragments, often colonizing their surface through the formation of biofilms (Lobelle & Cunliffe, 2011;Oliveira et al, 2021). A mature biofilm can impact physical properties of the colonized polymer, altering its crystallinity, molecular weight, hydrophobicity, surface morphology, and buoyance (Luo et al, 2021).…”

“…The natural weathering of polymers in the environment, for instance, increases surface roughness and impacts biofilm formation. Our previous work has shown that the adhesion of marine bacteria to microplastics is impacted by surface weathering, to which bacteria respond by increasing the production of extracellular matrix (Oliveira et al, 2021). In this context, a similar characterization of marine yeast biofilms has not been addressed.…”