Microbial colonization patterns and biodegradation of petrochemical and biodegradable plastics in lake waters: insights from a field experiment

Abstract

IntroductionOnce dispersed in water, plastic materials become promptly colonized by biofilm-forming microorganisms, commonly known as plastisphere.MethodsBy combining DNA sequencing and Confocal Laser Scanning Microscopy (CLSM), we investigated the plastisphere colonization patterns following exposure to natural lake waters (up to 77 days) of either petrochemical or biodegradable plastic materials (low density polyethylene - LDPE, polyethylene terephthalate - PET, polylactic acid - PLA, and the starch-based MaterBi® - Mb) in comparison to planktonic community composition. Chemical composition, water wettability, and morphology of plastic surfaces were evaluated, through Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), and static contact angle analysis, to assess the possible effects of microbial colonization and biodegradation activity.Results and DiscussionThe phylogenetic composition of plastisphere and planktonic communities was notably different. Pioneering microbial colonisers, likely selected from lake waters, were found associated with all plastic materials, along with a core of more than 30 abundant bacterial families associated with all polymers. The different plastic materials, either derived from petrochemical hydrocarbons (i.e., LDPE and PET) or biodegradable (PLA and Mb), were used by opportunistic aquatic microorganisms as adhesion surfaces rather than carbon sources. The Mb-associated microorganisms (i.e. mostly members of the family Burkholderiaceae) were likely able to degrade the starch residues on the polymer surfaces, although the Mb matrix maintained its original chemical structure and morphology. Overall, our findings provide insights into the complex interactions between aquatic microorganisms and plastic materials found in lake waters, highlighting the importance of understanding the plastisphere dynamics to better manage the fate of plastic debris in the environment.

Freshwater plastisphere: a review on biodiversity, risks, and biodegradation potential with implications for the aquatic ecosystem health

“…Few studies currently available report inconsistent results on the direct involvement of plastisphere in biodegradation processes. The metabolic potential to hydrolyse and use the plastic polymers as carbon sources was not convincingly demonstrated, while plastic materials were mostly used as adhesion surfaces by opportunistic aquatic microbes ( Oberbeckmann et al, 2021 ; Di Pippo et al, 2023 ). Further investigations are thus needed to provide a deeper understanding of plastisphere role in plastic biodegradation.…”

Biodegradation of Nitrile Gloves as Sole Carbon Source of Pseudomonas aeruginosa in Liquid Culture

“…Additionally, nitrile groups are known to be highly toxic, mutagenic, and carcinogenic, as reported in recent studies by Gong et al [ 11 ] and Nigam et al [ 12 ]. Moreover, plastics and microplastics have the potential to transport chemical pollutants, as well as microorganisms capable of forming biofilms [ 13 ].…”