Edge-Localized Biodeterioration and Secondary Microplastic Formation by Papiliotrema laurentii Unsaturated Biofilm Cells on Polyurethane Films

Abstract

Painted environmental surfaces are prone to microbiological colonization with potential coating deterioration induced by the microorganisms. Accurate mechanistic models of these interactions require an understanding of the heterogeneity in which the deterioration processes proceed. Here, unsaturated biofilms (i.e., at air/solid interfaces) of the yeast Papiliotrema laurentii were prepared on polyether polyurethane (PEUR) and polyester-polyether polyurethane (PEST-PEUR) coatings and incubated for up to 33 days at controlled temperature and humidity with no additional nutrients. Transmission micro-Fourier transform infrared microscopy (μFTIR) confirmed preferential hydrolysis of the ester component by the biofilm. Atomic force microscopy combined with infrared nanospectroscopy (AFM-IR) was used to analyze initial PEST-PEUR coating deterioration processes at the single-cell level, including underlying surfaces that became exposed following cell translocation. The results revealed distinct deterioration features that remained localized within ∼10 μm or less of the edges of individual cells and cell clusters. These features comprised depressions of up to ∼300 nm with locally reduced ester/urethane ratios. They are consistent with a formation process initiated by enzymatic ester hydrolysis followed by erosion from water condensation cycles. Further observations included particle accumulation in the broader biofilm vicinity. AFM-IR spectroscopy indicated these to be secondary microplastics consisting of urethane-rich oligomeric aggregates. Overall, multiple contributing factors have been identified that can facilitate differential deterioration rates across the PEST-PEUR surface. Effects of the imposed nutrient conditions on Papiliotrema laurentii physiology were also apparent, with cells developing the characteristics of starvation response, despite the availability of polyester metabolites as a carbon source. The combined results provide new laboratory insights into field-relevant microbiological polymer deterioration mechanisms and biofilm physiology at polymer coating interfaces.

Current progress towards understanding the biodegradation of synthetic condensation polymers with active hydrolases

“…The complete hydrolysis of polyurethanes is important because partially degraded polyurethanes will increase the amount of microplastics in the environment. We have observed polyurethane microplastic release in our experiments, 61 and there are several groups attempting to degrade microplastics from different angles. One approach has been to agglomerate the microplastics into larger particulates to reduce their movement in the environment.…”

“…[58][59][60] We have recently shown that urethane-rich nanoparticles and microparticles were released during the fungal degradation of a polyester polyether polyurethane coating with analytical data supporting only polyester hydrolysis. 61 It would be inaccurate to describe our results as 'polyurethanase' activity. However, while 'polyurethanase' is not an accurate classification, urethanase is accurate since many of the articles describing urethanease activity focus on the degradation of ethyl carbamate, a carcinogen that can be present in fermented foods and drinks.…”

The Effect of Rumen Microbiota in The Susceptibility of Subacute Ruminal Acidosis in Dairy Cows

“…Fusarium_oxysporum, an economically important lamentous fungus species of Fusarium, is a large species complex of among plant, animal and human pathogens that attack a diverse array of species in a host-speci c manner [30,31]. Papiliotrema_laurentii is a yeast that commonly inhibits in soil and plant, and has ability to hydrolyze polyester coatings and coat components [32]. Studies also suggested that Papiliotrema_laurentii can accumulate intracellular lipids from inulin hydrolysates [33].…”

Assessment of Microplastics in a Municipal Wastewater Treatment Plant With Tertiary Treatment: Removal Efficiencies and Loading Per Day Into the Environment

“…Primary MPs are used in the form of spherules as precursors in the plastic industry, with a wide range of applications such as packaging, o ce equipment, and vehicle construction, or as scrubbing material in personal care products or air-blasting granules and pellets, among other uses (Mani et al 2015). Barlow et al 2020). Microplastics are considered to be more prevalent in the environment than macro or mesoplastics, owning their larger quantities and small sizes (Karbalaei et al 2018).…”

“…Primary MPs are used in the form of spherules as precursors in the plastic industry, with a wide range of applications such as packaging, o ce equipment, and vehicle construction, or as scrubbing material in personal care products or air-blasting granules and pellets, among other uses (Mani et al 2015). Secondary MPs are formed by means of chemical and physical mechanisms such as hydrolytic degradation, photolysis, weathering, ultraviolet radiation or abrasion (Ziajahromi et al 2017;Arhant et al 2019), or via biotic degradation, as biodeterioration (Jang et al 2018; Barlow et al 2020). Microplastics are considered to be more prevalent in the environment than macro or mesoplastics, owning their larger quantities and small sizes (Karbalaei et al 2018).…”