Bioaccessibility of Microplastic-Associated Antibiotics in Freshwater Organisms: Highlighting the Impacts of Biofilm Colonization via an In Vitro Protocol

Abstract

Microplastics in the environment can be colonized by microbes capable of forming biofilms, which may act as reactive coatings to affect the bioaccessibility of pollutants in organisms. This study investigated the dynamic evolution of biofilm colonization on microplastics and its impacts and mechanisms on the bioaccessibility of microplastic-associated sulfamethazine (SMT) via microcosm incubation in surface water and sediment. After 60 days of incubation, the microbial communities formed in microplastics were distinct and more diverse than those untethered in surroundings, and photoaging treatment decreased the affinity of biofilms on microplastics due to decreased hydrophobicity. Biofilm formation further enhanced the desorption and bioaccessibility of microplastic-sorbed SMT in organisms. In vitro experiments indicated that the critical effects were mainly related to the stronger interaction of gastrointestinal components (i.e., pepsin, bovine serum albumin (BSA), and NaT) with biofilm components (e.g., extracellular polymer substances) than with the pure surface of microplastics, which competed for binding sites in microplastics for SMT more significantly. Photoaging decreased the enhancing effects of biofilms due to their lower accumulation in aged microplastics. This study is the first attempt to reveal the role of biofilms in the bioaccessibility of microplastics with associated antibiotics and provide insights into the combined risk of microplastics in the environment.

Biofilm-Colonized versus Virgin Black Microplastics to Accelerate the Photodegradation of Tetracycline in Aquatic Environments: Analysis of Underneath Mechanisms

“…During the 45 day incubation period, estimation of the biomass of a biofilm using the CV analysis presented a significant (4−5 fold) increase in the amount of biomass (Figure 1A), confirming biofilm formation on TWPs. 8 Correspondingly, SEM analysis verified biofilm formation by revealing microbial adhesion and biofilm formation on TWPs during incubation. The V-TWPs exhibited an uneven and a rather smooth surface [Figure 1D (a1−b1)].…”

“…The adsorption of TC on V-TWPs and Bio-TWPs was better fitted to a pseudo-second-order kinetic model than to a pseudo-first-order kinetic model, and the regression coefficient of the pseudo-second-order kinetic model for Bio-TWPs was greater than that for V-TWPs (Figure S6A and Table S4). The pseudo-first-order model represents the unoccupied sites on the substrate by adsorbates, and the chemical sorption is dominant on the pseudo-second-order model . Both pseudo-second-order kinetic models fit better than pseudo-first-order models in Bio-TWPs, suggesting that TC adsorption on biofilm-covered surfaces was predominantly chemical interactions.…”

“…The pseudo-first-order model represents the unoccupied sites on the substrate by adsorbates, and the chemical sorption is dominant on the pseudo-secondorder model. 8 Both pseudo-second-order kinetic models fit better than pseudo-first-order models in Bio-TWPs, suggesting that TC adsorption on biofilm-covered surfaces was predominantly chemical interactions. In Figure S6B, the Langmuir model accurately represented the behavior of TC adsorption (R 2 = 0.985/0.994 in Table S5), demonstrating that TC adsorbed on the uniform surface of TWPs could generate a monolayer.…”

“…MPs exposed to the natural environment are readily colonized by microorganisms capable of forming biofilms. , Findings in recent studies have indicated that microbial colonization of MPs can influence their surface hydrophobicity, crystallinity, and topography, which is proven to have high affinity for microbial settlement and biofilm growth under certain environmental conditions . Biofilms could potentially modify the adsorption characteristics of MPs and amplify the role of MPs in contaminant (antibiotics and others) migration. , This increases the interaction between MPs and environmental pollutants. However, the knowledge of biofilm colonization on TWPs and associated environmental behavior remains limited.…”

“…10 amplify the role of MPs in contaminant (antibiotics and others) migration. 8,11 This increases the interaction between MPs and environmental pollutants. However, the knowledge of biofilm colonization on TWPs and associated environmental behavior remains limited.…”