Reclaimed wastewater reuse in irrigation: Role of biofilms in the fate of antibiotics and spread of antimicrobial resistance. (1st August 2022)

• Record Type: Journal Article
• Authors: Brienza, M.; Sauvêtre, A.; Ait-Mouheb, N.; Bru-Adan, V.; Coviello, D.; Lequette, K.; Patureau, D.; Chiron, S.; Wéry, N.
• Is Part Of: Water research. Volume 221(2022)
• Publication Date: 2022-08-01
• Subjects: Biofilms -- ARGs -- Antibiotics -- Reclaimed wastewater reuse -- Irrigation; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2022.118830
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Antibiotics degradation by interactions between planktonic and biofilm bacteria. Antibiotic exposure had no impact on the planktonic bacterial communities. Resistance selection and propagation in biofilms are generated from bacterial community composition and diversity. Antibiotic exposure is not a driving force for resistance selection and propagation in biofilm. Abstract: Reclaimed wastewater associated biofilms are made up from diverse class of microbial communities that are continuously exposed to antibiotic residues. The presence of antibiotic resistance bacteria (ARB) and their associated antibiotic resistance genes (ARGs) ensures also a continuous selection pressure on biofilms that could be seen as hotspots for antibiotic resistance dissemination but can also play a role in antibiotic degradation. In this study, the antibiotic degradation and the abundance of four ARGs ( qnr S, sul 1, bla TEM, erm B), and two mobile genetic elements (MGEs) including IS 613 and intl 1, were followed in reclaimed wastewater and biofilm samples collected at the beginning and after 2 weeks of six antibiotics exposure (10 µg L −1 ). Antibiotics were partially degraded and remained above lowest minimum inhibitory concentration (MIC) for environmental samples described in the literature. The most abundant genes detected both in biofilms and reclaimed wastewater were sul 1, erm B, and intl 1. The relative abundance of these genes in biofilms increased during the 2 weeks of exposure but the highest values were found in control samples (without antibiotics pressure), suggesting that bacterial community composition and diversity are the driven forces for resistance selection and propagation in biofilms, rather than exposure to antibiotics. Planktonic and biofilm bacterial communities were characterized. Planktonic cells are classically defined "as free flowing bacteria in suspension" as opposed to the sessile state (the so-called biofilm): "a structured community of bacterial cells enclosed in a self-produced polymeric matrix and adherent to an inert or living. surface" as stated by Costerton et al. (1999) . The abundance of some genera known to harbor ARG such as Streptococcus, Exiguobacterium, Acholeplasma, Methylophylaceae and Porphyromonadaceae increased in reclaimed wastewater containing antibiotics. The presence of biofilm lowered the level of these genera in wastewater but, at the opposite, could also serve as a reservoir of these bacteria to re-colonize low-diversity wastewater. It seems that maintaining a high diversity is important to limit the dissemination of antimicrobial resistance among planktonic bacteria. Antibiotics had no influence on the biofilm development monitored with optical coherence tomography (OCT). Further research is needed in order to clarify the role of inter-species communication in biofilm on antibiotic degradation and resistance development and spreading.