Influence of microplastic-associated biofilms on the bioavailability of a mixture of cadmium and benzo[a]pyrene by the analysis of biomarker gene expression in larval zebrafish

Marilena Di Natale, Ana Isabel Catarino, Stephen Summers, David Boyle, Marco Torri, Aldo Nicosia, Marianna Musco, Tiziana Masullo, Stefania Russo, Carmelo Daniele Bennici, Antonio Mazzola, Angela Cuttitta, Theodore B. Henry

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Abstract

Microplastics (MPs, 1 µm – 5 mm) in aquatic environments undergo complex weathering transformations such as those induced by microbial colonization and biofilm formation, that affect their ability to interact with environmental contaminants (co-contaminants). In this study, the microbial composition of MP biofilms and its influence on the sorption and bioavailability of two co-contaminants with different physicochemistry, benzo[a]pyrene (B[a]P) and cadmium (Cd) in a mixture, were assessed. Aqueous-phase bioavailability was measured by assessment of biomarker gene expression for these toxicants (cytochrome P450 1A, cyp1a, and metallothionein 2, mt2, for B[a]P and Cd respectively) in larval zebrafish, Danio rerio. Significant induction of cyp1a and mt2 gene expression (p < 0.05) was observed after exposure to the mixture of Cd, B[a]P and MPs compared to joint exposure with individual contaminants and MPs. Significant changes in bioavailability for mt2 biomarker (p < 0.001) resulted after exposure to a Cd and B[a]P mixture with MPs compared to the same exposure without MPs. Biofilms significantly reduced bioavailability of B[a]P (cyp1a gene expression (p < 0.01)) but not Cd (mt2 gene expression) in the mixture with Cd and B[a]P (HDPE + BF + B[a]P + Cd) compared to the same treatment without biofilm (HDPE + B[a]P + Cd). Thus, compared to Cd, the biofilm could provide additional interactions with B[a]P, and new specific active sites on the MPs surface, that reduced B[a]P bioavailability. Additionally, the biofilm microbial community included hydrocarbon-degrading bacteria able to metabolize hydrophobic chemicals. These data indicated that in a mixture of co-contaminants, the biofilm selectively influenced their bioavailability and that the microbial composition of MPs biofilm may have played a key role in reducing B[a]P bioavailability. The results of this study highlight how in a complex exposure scenario characterized by a mixture of different co-contaminants, the polymer and chemical properties and micro-surroundings of the organisms may affect contaminants' bioavailability and/or exposure.
Original languageEnglish
Article number110369
JournalEcological Indicators
Volume152
Early online date20 May 2023
DOIs
Publication statusPublished - Aug 2023

Keywords

  • Bioavailability
  • Biofilm
  • Contaminants
  • Microplastics
  • Mixture
  • Sorption
  • Zebrafish

ASJC Scopus subject areas

  • General Decision Sciences
  • Ecology, Evolution, Behavior and Systematics
  • Ecology

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