Coalescence of bacterial groups originating from urban runoffs and artificial infiltration systems among aquifer microbiomes
<p>The invasion of aquifer microbial communities by aboveground microorganisms, a phenomenon known as community coalescence, is likely to be exacerbated in groundwaters fed by stormwater infiltration systems (SISs). Here, the incidence of this increased connectivity with upslope soils and impe...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-08-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://hess.copernicus.org/articles/24/4257/2020/hess-24-4257-2020.pdf |
| Summary: | <p>The invasion of aquifer microbial communities by aboveground
microorganisms, a phenomenon known as community coalescence, is likely to be
exacerbated in groundwaters fed by stormwater infiltration systems (SISs).
Here, the incidence of this increased connectivity with upslope soils and
impermeabilized surfaces was assessed through a meta-analysis of 16S rRNA
gene libraries. Specifically, DNA sequences encoding 16S rRNA V5-V6 regions from free-living
and attached aquifer bacteria (i.e., water and biofilm samples) were
analysed upstream and downstream of a SIS and compared with those from
bacterial communities from watershed runoffs and surface sediments from the
SIS detention and infiltration basins. Significant bacterial transfers were
inferred by the SourceTracker Bayesian approach, with 23 % to 57 % of the
aquifer bacterial biofilms being composed of taxa from aboveground sediments
and urban runoffs. Sediments from the detention basin were found more
significant contributors of taxa involved in the buildup of these biofilms
than soils from the infiltration basin. Inferred taxa among the coalesced
biofilm community were predicted to be high in hydrocarbon degraders such as
<i>Sphingobium</i> and <i>Nocardia</i>. The 16S rRNA-based bacterial community structure of the downstream-SIS
aquifer waters showed lower coalescence with aboveground taxa (8 % to 38 %)
than those of biofilms and higher numbers of taxa predicted to be involved
in the N and S cycles. A DNA marker named <i>tpm</i> enabled the tracking of
bacterial species from 24 genera including <i>Pseudomonas</i>, <i>Aeromonas </i>and <i>Xanthomonas</i>, among these
communities. Several <i>tpm</i> sequence types were found to be shared between the
aboveground and aquifer samples. Reads related to <i>Pseudomonas</i> were allocated to 50
species, of which 16 were found in the aquifer samples. Several of these
aquifer species were found to be involved in denitrification but also
hydrocarbon degradation (<i>P. aeruginosa</i>, <i>P. putida</i> and <i>P. fluorescens</i>). Some <i>tpm</i> sequence types allocated to <i>P. umsongensis</i> and <i>P. chengduensis</i> were
found to be enriched among the <i>tpm</i>-harbouring bacteria, respectively, of the
aquifer biofilms and waters. Reads related to <i>Aeromonas</i> were allocated to 11
species, but only those from <i>A. caviae</i> were recovered aboveground and in the aquifer
samples. Some <i>tpm</i> sequence types of the <i>X. axonopodis</i> phytopathogen were recorded in higher
proportions among the <i>tpm</i>-harbouring bacteria of the aquifer waters than in the
aboveground samples. A significant coalescence of microbial communities from
an urban watershed with those of an aquifer was thus observed, and recent
aquifer biofilms were found to be significantly colonized by runoff-opportunistic taxa able to use urban C sources from aboveground
compartments.</p> |
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| ISSN: | 1027-5606 1607-7938 |