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Drinking Water Microbiome

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Front. Microbiol. | doi: 10.3389/fmicb.2019.00028

Spring water of an alpine karst aquifer is dominated by a taxonomically stable but discharge-responsive bacterial community

 Domenico Savio1, 2*, Philipp Stadler1,  Georg H. Reischer1, Katalin Demeter1, Rita B. Linke1, Alfred P. Blaschke1, Hermann Stadler3,  Robert L. Mach1,  Alexander K. Kirschner4 and  Andreas H. Farnleitner1, 2, 5*
  • 1Centre for Water Resource Systems, Vienna University of Technology, Austria
  • 2Department Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences Tulln, Austria
  • 3Department for Water Resources Management and Environmental Analytics, Institute for Water, Energy and Sustainability, Joanneum Research, Austria
  • 4Unit Water Hygiene, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Austria
  • 5Interuniversity Cooperation Centre Water & Health, Austria

Alpine karst aquifers are important groundwater resources for the provision of drinking water around the world. Yet, due to difficult accessibility and long-standing methodological limitations, the microbiology of these systems has long been understudied. The aim of the present study was to investigate the structure and dynamics of bacterial communities in spring water of an alpine limestone karst aquifer (LKAS2) under different hydrological conditions (base vs. event flow). The study was based on 16S rRNA gene amplicon sequencing, study design and sample selection were guided by hydrology and pollution microbiology data. Spanning more than 27 months, our analyses revealed a taxonomically highly stable bacterial community, comprising high proportions of yet uncultivated bacteria in the suspended bacterial community fraction. Only the three candidate phyla Parcubacteria (OD1), Gracilibacteria (GN02), Doudnabacteria (SM2F11) together with Proteobacteria and Bacteroidetes contributed between 70.0 and 88.4 % of total reads throughout the investigation period. A core-community of 300 OTUs consistently contributed between 37.6 and 56.3 % of total reads, further supporting the hypothesis of a high temporal stability in the bacterial community in the spring water. Nonetheless, a detectable response in the bacterial community structure of the spring water was discernible during a high-discharge event. Sequence reads affiliated to the class Flavobacteriia clearly increased from a mean proportion of 2.3 % during baseflow to a maximum of 12.7 % during the early phase of the studied high-discharge event, suggesting direct impacts from changing hydrological conditions on the bacterial community structure in the spring water. This was further supported by an incline of species richness (Chao 1) at higher discharge. The combination of these observations also allowed the identification and characterization of three different discharge classes (Q1-Q3). In conclusion, we found a taxonomically stable bacterial community prevailing over more than two years in spring waters from an alpine karst aquifer. Clear response to changing discharge conditions could be detected for particular bacterial groups, whereas the most responsive group – bacteria affiliated to the class of Flavobacteriia – might harbor potential as a valuable natural indicator of ‘system disturbances’ in karst aquifers.

Keywords: Alpine karst spring, Spring water microbiome, High-discharge event, Base flow, high-throughput sequencing

Received: 31 Jul 2018; Accepted: 09 Jan 2019.

Edited by:

Frederik Hammes, Swiss Federal Institute of Aquatic Science and Technology, Switzerland

Reviewed by:

David G. Weissbrodt, Delft University of Technology, Netherlands
Stefano Amalfitano, Istituto di ricerca sulle acque (IRSA), Italy
Blake W. Stamps, Colorado School of Mines, United States  

Copyright: © 2019 Savio, Stadler, Reischer, Demeter, Linke, Blaschke, Stadler, Mach, Kirschner and Farnleitner. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Dr. Domenico Savio, Vienna University of Technology, Centre for Water Resource Systems, Vienna, 1040, Vienna, Austria, domenico.savio@kl.ac.at
Prof. Andreas H. Farnleitner, Karl Landsteiner University of Health Sciences Tulln, Department Pharmacology, Physiology and Microbiology, Tulln, Austria, andreas.farnleitner@kl.ac.at