Bottled aqua incognita: Microbiota assembly and dissolved organic matter diversity in natural mineral waters

Abstract

BackgroundNon-carbonated natural mineral waters contain microorganisms that regularly grow after bottling despite low concentrations of dissolved organic matter (DOM). Yet, the compositions of bottled water microbiota and organic substrates that fuel microbial activity, and how both change after bottling, are still largely unknown.ResultsWe performed a multifaceted analysis of microbiota and DOM diversity in twelve natural mineral waters from six European countries. 16S rRNA gene-based analyses showed that less than ten species-level operational taxonomic units (OTUs) dominated the bacterial communities in the water phase and associated with the bottle wall after a short phase of post-bottling growth. Members of the betaproteobacterial genera Curvibacter, Aquabacterium, and Polaromonas (Comamonadaceae) grew in most waters and represent ubiquitous, mesophilic, heterotrophic aerobes in bottled waters. Ultrahigh-resolution mass spectrometry of DOM in bottled waters and their corresponding source waters identified thousands of molecular formulae characteristic of mostly refractory, soil-derived DOM.ConclusionsThe bottle environment, including source water physicochemistry, selected for growth of a similar low-diversity microbiota across various bottled waters. Relative abundance changes of hundreds of multi-carbon molecules were related to growth of less than ten abundant OTUs. We thus speculate that individual bacteria cope with oligotrophic conditions by simultaneously consuming diverse DOM molecules.

Extracellular DNA in Monochloraminated Drinking Water and Its Influence on DNA-Based Profiling of a Microbial Community

“…Curvibacter is known to be present in oligotrophic drinking water sources. 45 It was detected in the control samples at location 2 but became undetectable after eDNA was removed (FC = 1). Similarly, the detected abundance of Caulobacter and Hydrogenophaga decreased substantially after eDNA was removed (FC = 0.8−0.9).…”

Travel Time and Source Variation Explain the Molecular Transformation of Dissolved Organic Matter in an Alpine Stream Network

“…After internal calibration, raw mass lists were exported from Bruker's Data Analysis software at signal/noise (S/N) ≥ 5 for further data processing using in‐house code in R. First, molecular formulae were assigned to m / z values assuming single‐charged deprotonated molecular ions and Cl‐adducts for a maximum elemental combination of C 100 H 250 O 80 N 4 P 2 S 2 . This happened for each spectrum individually with (i) a conservative mass tolerance of 0.4 ppm, (ii) commonly assumed restrictions of elemental composition (Lesaulnier et al, 2017), and (iii) a check for isotope confirmation (based on adequate mass shift with a tolerance of 0.4 ppm and adequate intensity ratio(s) of isotopic peaks to the monoisotopic parent peak within 20%). In case of multiple formula assignments to the same peak, we gave preference to formulae with better isotope confirmation (more complete isotope pattern) and formulae involved in longer homologous series based on CH 2 (aliphatic elongation), CO 2 (acid‐based elongation), or both (2D molecular network) in this ranked order.…”

Dry phase conditions prime wet‐phase dissolved organic matter dynamics in intermittent rivers

“…S6); plotting order was random to avoid bias created by systematic overplotting of thousands of compounds. To condense the rich mass‐spectrometric information, we grouped formulas into 12 nonoverlapping molecular groups (Santl‐Temkiv et al ; Seidel et al ; Lesaulnier et al ) based on elemental composition and structural information derived from the aromaticity index (AI) (Koch and Dittmar ). We then summed up raw monoisotopic peak intensities of all formulas assigned to a molecular group as a semiquantitative proxy of concentration (Table ).…”