Triclosan changes community composition and selects for specific bacterial taxa in marine periphyton biofilms in low nanomolar concentration
- Published
- Accepted
- Subject Areas
- Biodiversity, Bioinformatics, Genetics, Ecotoxicology
- Keywords
- metabarcoding, amplicon sequencing, ecological risk assessment, rRNA, microbial toxicology, marine toxicity tests
- Copyright
- © 2018 Eriksson et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2018. Triclosan changes community composition and selects for specific bacterial taxa in marine periphyton biofilms in low nanomolar concentration. PeerJ Preprints 6:e27125v1 https://doi.org/10.7287/peerj.preprints.27125v1
Abstract
The antibacterial agent Triclosan (TCS) is an ubiquitous environmental contaminant due to its widespread use. Sensitivity to TCS varies substantially among eu- and pro-karyotic species and its risk for the marine environment remains to be better elucidated. In particular, the effects that TCS causes on marine microbial communities are largely unknown. In this study we therefore used 16S amplicon rDNA sequencing to investigate TCS effects on the bacterial composition in marine periphyton communities that developed under long-term exposure to different TCS concentrations. Exposure to TCS resulted in clear changes in bacterial composition already at concentrations of 1 to 3.16 nM. We conclude that TCS affects the structure of the bacterial part of periphyton communities at concentrations that actually occur in the marine environment. Sensitive taxa, whose abundance decreased significantly with increasing TCS concentrations, include the Rhodobiaceae and Rhodobacteraceae families of Alphaproteobacteria, and unidentified members of the Candidate division OD1. Tolerant taxa, whose abundance increased significantly with higher TCS concentrations, include the families Erythrobacteraceae (Alphaproteobacteria), Flavobacteriaceae (Bacteroidetes), Bdellovibrionaceae (Deltaproteobacteria), several families of Gammaproteobacteria, and members of the Candidate phylum BD1-5. Our results demonstrate the variability of TCS sensitivity among bacteria, and the importance of extending the ecotoxicological assessment of antimicrobial chemicals, such as TCS, to non-cultivable bacteria and natural communities.
Author Comment
This study address effects of the antibacterial compound triclosan on the genetic composition of bacteria in natural marine biofilm communities. Triclosan is a high-volume chemical and its use and potential effects have been highly debated in science as well as in society in general. The compound has been detected in both freshwater and marine environments. In the scientific literature there are a number of studies addressing effects of triclosan on freshwater organisms and microbial communities. However, only a few studies have addressed its effects on marine microbial communities, and none of those have used modern DNA sequencing methods. The study describes concentration-response effects of triclosan on bacterial genetic composition and diversity after 17 days of exposure in marine flow-through microcosms. The flow-through nature of this experiment, as well as the use of periphyton (biofilm) communities, renders this study a high degree of ecological realism. The study use high-throughput next generation DNA sequencing of 16S amplicons from samples exposed to a gradient of triclosan concentrations.
Our study shows that TCS has effects on bacterial composition at nanomolar concentrations – concentrations that have been detected in the marine environment. Hence, the study is of great interest for any ecological risk assessment of triclosan.
Supplemental Information
Supplementary figures and supplementary table 1 and 2
This file contains supplementary figures and supplementary table 1 and 2. Figure and table captions are present below and above the figures and tables, respectively.
Supplementary table 3
Exel file with 4 sheets. Three sheets contain statistics for pairwise comparisons of OTU relative abundance between unexposed control samples and low (3.16 nM), intermediate (31.6 nM) and high (316 nM) triclosan exposure. One sheet contain regression statistics of OTU relative abundance vs. triclosan concentration.