Triclosan enriches for Dehalococcoides-like Chloroflexi in anaerobic soil at environmentally relevant concentrations

Abstract Triclosan is an antimicrobial agent that is discharged to soils with land-applied wastewater biosolids, is persistent under anaerobic conditions, and yet its impact on anaerobic microbial communities in soils is largely unknown. We hypothesized that triclosan enriches for Dehalococcoides-li...

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Bibliographic Details
Published in:FEMS microbiology letters 2013-07, Vol.344 (1), p.48-52
Main Authors: McNamara, Patrick J., Krzmarzick, Mark J.
Format: Article
Language:English
Subjects:
Agricultural land
Anaerobic conditions
Antimicrobial agents
Biological and medical sciences
Biosolids
Chloroflexi - drug effects
Chloroflexi - genetics
Chloroflexi - metabolism
community fingerprinting
Dehalococcoides
emerging contaminants
Fundamental and applied biological sciences. Psychology
Microbial activity
Microbiology
Microcosms
organochloride respiration
RNA, Bacterial
RNA, Ribosomal, 16S
Soil - analysis
Soil Microbiology
Soil Pollutants - analysis
Soils
Triclosan - analysis
Triclosan - pharmacology
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Summary:Abstract Triclosan is an antimicrobial agent that is discharged to soils with land-applied wastewater biosolids, is persistent under anaerobic conditions, and yet its impact on anaerobic microbial communities in soils is largely unknown. We hypothesized that triclosan enriches for Dehalococcoides-like Chloroflexi because these bacteria respire organochlorides and are likely less sensitive, relative to other bacteria, to the antimicrobial effects of triclosan. Triplicate anaerobic soil microcosms were seeded with agricultural soil, which was not previously exposed to triclosan, and were amended with 1 mg kg−1 of triclosan. Triplicate control microcosms did not receive triclosan, and the experiment was run for 618 days. The overall bacterial community (assessed by automated ribosomal intergenic spacer analysis and denaturing gradient gel electrophoresis) was not impacted by triclosan; however, the abundance of Dehalococcoides-like Chloroflexi 16S rRNA genes (determined by qPCR) increased 20-fold with triclosan amendment compared with a fivefold increase without triclosan. This work demonstrates that triclosan impacts anaerobic soil communities at environmentally relevant levels.
ISSN:0378-1097
1574-6968
DOI:10.1111/1574-6968.12153