Primary succession of microbial communities in an aquifer from the Covey Hill formation in Quebec, Canada

Aquifers in the continental subsurface have long been exploited for their resources. However, given the technical difficulties in accessing recurring subsurface samples, their community diversity and temporal dynamics remain largely misunderstood. Here, we investigated the effects of time and organi...

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Main Authors: Samuel Beauregard-Tousignant, Cassandre Sara Lazar
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-05-01
Series:Frontiers in Microbiology
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Online Access:https://www.frontiersin.org/articles/10.3389/fmicb.2025.1568469/full
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author Samuel Beauregard-Tousignant
Samuel Beauregard-Tousignant
Cassandre Sara Lazar
Cassandre Sara Lazar
author_facet Samuel Beauregard-Tousignant
Samuel Beauregard-Tousignant
Cassandre Sara Lazar
Cassandre Sara Lazar
author_sort Samuel Beauregard-Tousignant
collection DOAJ
description Aquifers in the continental subsurface have long been exploited for their resources. However, given the technical difficulties in accessing recurring subsurface samples, their community diversity and temporal dynamics remain largely misunderstood. Here, we investigated the effects of time and organic and inorganic carbon concentration variation on primary succession of microbial communities belonging to the Bacteria and Eukaryote domains colonizing rock surfaces and groundwater from a shallow fractured sandstone aquifer with a very high concentration of organic carbon and low concentration of nitrogen compounds. We attempted to recreate its physicochemical environment in a triplicate bioreactor setup and let the communities grow for 24 days. The sessile and planktonic communities were sampled daily in independent experiments and identified based on their 16S (Bacteria) or 18S (Eukaryote) rRNA genes. Time was the parameter with the strongest correlation both with alpha and beta diversity. The primary succession of all communities seems to have been divided into two temporal phases: in the first phase, approximately the two 1st days, the variations in community composition and diversity were high. In the second phase, the variation is more progressive and lasted until the end of the experiment. As expected in an aquifer rich in organic carbon, bacteria were mostly heterotrophs, except in the first few days where there were some chemolithotrophs, and eukaryotes were heterotrophs or likely mixotrophs. Unexpectedly, the alpha diversity of the sessile and planktonic communities varied following similar patterns, but the planktonic ones varied with a wider amplitude. Regarding carbon's effect, organic and inorganic carbon concentration variation explained a much smaller proportion of the variation in alpha and beta diversity than expected. We believe this is due to its high concentration throughout the incubation and to the strong limiting effect of other factors such as nitrogen concentration and pH. The communities of both Bacteria and Eukaryotes were more active than expected and their temporal dynamics and interactions should be further investigated in varying carbon, nitrogen and other nutrient concentrations to better understand how different perturbations can affect subsurface communities and, subsequently, us.
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spelling doaj-art-0ccbd2cb964c4c639d58acd22f621c6b2025-08-20T03:08:17ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2025-05-011610.3389/fmicb.2025.15684691568469Primary succession of microbial communities in an aquifer from the Covey Hill formation in Quebec, CanadaSamuel Beauregard-Tousignant0Samuel Beauregard-Tousignant1Cassandre Sara Lazar2Cassandre Sara Lazar3Biological Sciences Department, Université du Québec à Montréal (UQAM), Montreal, QC, CanadaInteruniversity Research Group in Limnology/Groupe de Recherche Interuniversitaire en Limnologie (GRIL), Montreal, QC, CanadaBiological Sciences Department, Université du Québec à Montréal (UQAM), Montreal, QC, CanadaInteruniversity Research Group in Limnology/Groupe de Recherche Interuniversitaire en Limnologie (GRIL), Montreal, QC, CanadaAquifers in the continental subsurface have long been exploited for their resources. However, given the technical difficulties in accessing recurring subsurface samples, their community diversity and temporal dynamics remain largely misunderstood. Here, we investigated the effects of time and organic and inorganic carbon concentration variation on primary succession of microbial communities belonging to the Bacteria and Eukaryote domains colonizing rock surfaces and groundwater from a shallow fractured sandstone aquifer with a very high concentration of organic carbon and low concentration of nitrogen compounds. We attempted to recreate its physicochemical environment in a triplicate bioreactor setup and let the communities grow for 24 days. The sessile and planktonic communities were sampled daily in independent experiments and identified based on their 16S (Bacteria) or 18S (Eukaryote) rRNA genes. Time was the parameter with the strongest correlation both with alpha and beta diversity. The primary succession of all communities seems to have been divided into two temporal phases: in the first phase, approximately the two 1st days, the variations in community composition and diversity were high. In the second phase, the variation is more progressive and lasted until the end of the experiment. As expected in an aquifer rich in organic carbon, bacteria were mostly heterotrophs, except in the first few days where there were some chemolithotrophs, and eukaryotes were heterotrophs or likely mixotrophs. Unexpectedly, the alpha diversity of the sessile and planktonic communities varied following similar patterns, but the planktonic ones varied with a wider amplitude. Regarding carbon's effect, organic and inorganic carbon concentration variation explained a much smaller proportion of the variation in alpha and beta diversity than expected. We believe this is due to its high concentration throughout the incubation and to the strong limiting effect of other factors such as nitrogen concentration and pH. The communities of both Bacteria and Eukaryotes were more active than expected and their temporal dynamics and interactions should be further investigated in varying carbon, nitrogen and other nutrient concentrations to better understand how different perturbations can affect subsurface communities and, subsequently, us.https://www.frontiersin.org/articles/10.3389/fmicb.2025.1568469/fullcontinental subsurfacemicrobial communitiessessile microbesmicrobial community successiongenomics
spellingShingle Samuel Beauregard-Tousignant
Samuel Beauregard-Tousignant
Cassandre Sara Lazar
Cassandre Sara Lazar
Primary succession of microbial communities in an aquifer from the Covey Hill formation in Quebec, Canada
Frontiers in Microbiology
continental subsurface
microbial communities
sessile microbes
microbial community succession
genomics
title Primary succession of microbial communities in an aquifer from the Covey Hill formation in Quebec, Canada
title_full Primary succession of microbial communities in an aquifer from the Covey Hill formation in Quebec, Canada
title_fullStr Primary succession of microbial communities in an aquifer from the Covey Hill formation in Quebec, Canada
title_full_unstemmed Primary succession of microbial communities in an aquifer from the Covey Hill formation in Quebec, Canada
title_short Primary succession of microbial communities in an aquifer from the Covey Hill formation in Quebec, Canada
title_sort primary succession of microbial communities in an aquifer from the covey hill formation in quebec canada
topic continental subsurface
microbial communities
sessile microbes
microbial community succession
genomics
url https://www.frontiersin.org/articles/10.3389/fmicb.2025.1568469/full
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