Microbial biofilm composition and polymer degradation of compostable and non-compostable plastics immersed in the marine environment

Abstract

Different plastic types considered as compostable are found on the market such as petro-based (e.g., polybutylene adipate terephthalate (PBAT)) or bio-based plastics (e.g., polylactic acid, (PLA)). Even if their degradation has been confirmed in industrial compost conditions, investigation of their degradation in natural marine environment has been limited. To better understand biodegradation into natural marine environment, commercial compostable (PBAT, semi-crystalline and amorphous PLA) and non-compostable polymers (low density polyethylene, polystyrene, polyethylene terephthalate, polyvinyl chloride) were submerged in situ on the sediment and in the water column in the Mediterranean Sea. These samples were studied by chemical and microbiological approaches. After 82 days of immersion, no significant bacterial degradation of the different polymers was observed, except some abiotic alterations of PBAT and LDPE probably due to a photooxidation process. However, after 80 days in an enrichment culture containing plastic films as a main carbon source, Marinomonas genus was specifically selected on the PBAT and a weight loss of 12% was highlighted. A better understanding of the bacterial community colonizing these plastics is essential for an eco-design of new biodegradable polymers to allow a rapid degradation in aquatic environment.

Physicochemical and biological ageing processes of (micro)plastics in the environment: a multi-tiered study on polyethylene

“…However, similarly to previous biofouling experiments performed in the field (Delacuvellerie et al 2021), the changes in surface properties are observed to be not homogeneous across the particle surface in the different samples. This is observable, for example, by the appearance of the sharp peak of glycosidic bond in only half of the samples (Fig.…”

“…Our multi-tiered laboratory test confirms this hypothesis, showing that plastic surface physicochemical properties are strongly affected by biofouling. Since the colonization of plastic surfaces by different microorganisms has been reported for litter and microplastics collected in a variety of aquatic systems (Nava and Leoni 2021;Delacuvellerie et al 2021;Deng et al 2021;, this process needs further investigation in future studies, in order to more realistically mimic the environmental behavior of (micro) plastics.…”

“…Studies of plastic ageing in environmental settings showed that biofilm's structural and functional features are controlled by the environmental conditions and substrate types (Delacuvellerie et al 2021;Barros and Seena 2021; Fig. 7 Score plot of principal components 1 and 2 (explained variance is indicated in parenthesis).…”

Biodegradable plastics in the marine environment: a potential source of risk?

“…Molecular weight reduction, mainly caused by the chain shortening, is a representative indicator for the hydrolysis of BPs, since only in hydrolysis can there be a measurable and significant molecular weight reduction. Due to this, a greater weight loss ratio than molecular weight reduction indicates that surface erosion predominates, such as that for PCL [50,52] and PHA [47] . A contrary situation indicates that bulk erosion is more important than surface erosion at this stage, as happens to PBS, PBAT [52] , and PLA [50] .…”

Effect of land use on microplastic pollution in a major boundary waterway: The Arvand River

“…As plastics are designed to last, plastic waste accumulate in the marine environment for long time (Delacuvellerie et al, 2021;Wang et al, 2016). Durign this period, and under the influence of a number of factors such as UV irradiation, oxidants, hydrolysis and mechanical abrasion, large plastic pieces disintegrate into smaller fragments (< 5 mm) (Song et al, 2017) generally J o u r n a l P r e -p r o o f referred to as MPs.…”