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Transcriptomic and rRNA:rDNA Signatures of Environmental versus Enteric Enterococcus faecalis Isolates under Oligotrophic Freshwater Conditions
Citation:
Suttner, B., M. Kim, E. Johnston, L. Orellana, C. Ruiz-Perez, L. Rodriguez-R, J. Hatt, J. Brown, J. SantoDomingo, AND K. Konstantinidis. Transcriptomic and rRNA:rDNA Signatures of Environmental versus Enteric Enterococcus faecalis Isolates under Oligotrophic Freshwater Conditions. Microbiology Spectrum. American Society for Microbiology, Washington, DC, 9(2):e00817-21, (2021). https://doi.org/10.1128/Spectrum.00817-21
Impact/Purpose:
The study looks at the fate of RNA and DNA ratios of the 16S rRNA gene and total RNA transcripts of an enterococci bacterial species in oligotrophic microcosms. Enterococci are used as indicators of fecal pollution in natural waters. The data provides an idea of how the ratios change over time
Description:
The use of enterococci as a fecal an indicator bacterial group for public health risk assessment has been brought into question by recent studies showing that “naturalized” populations of E. faecalis exist in the extraenteric environment in a viable but not culturable (VBNC) state. The extent to which these naturalized or VBNC E. faecalis can confound water quality monitoring is unclear. To determine if strains isolated from different habitats display different survival strategies and responses, we compared the decay patterns of three E. faecalis isolates from the natural environment (environmental strains) against three human gut isolates (enteric strains) in laboratory mesocosms that simulate an oligotrophic, aerobic freshwater environment. Our results showed similar overall decay rates between enteric and environmental isolates based on viable plate and qPCR counts. However, the enteric isolates exhibited a spike in rRNA:rDNA ratios between days 1 and 3 of the mesocosm incubations that was not observed in environmental isolates, which could indicate a different stress response. Nevertheless, there was no strong evidence of differential expression of genes thought to be related to habitat adaptation in the accompanying mesocosm metatranscriptomes when compared between environmental and enteric isolates. Overall, our results provide novel information on how rRNA levels may vary over different metabolic states (i.e., alive vs. VBNC) for this important indicator bacteria. We also observed some evidence for habitat adaptation in E. faecalis; however, this adaptation may not be substantial or consistent enough for integration in water quality monitoring.
URLs/Downloads:
DOI: Transcriptomic and rRNA:rDNA Signatures of Environmental versus Enteric Enterococcus faecalis Isolates under Oligotrophic Freshwater Conditions
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