Ubiquitous and persistent Proteobacteria and other Gram-negative bacteria in drinking water

Ivone Vaz-Moreira; Olga C Nunes; Célia M Manaia

doi:10.1016/j.scitotenv.2017.02.104

Ubiquitous and persistent Proteobacteria and other Gram-negative bacteria in drinking water

Sci Total Environ. 2017 May 15:586:1141-1149. doi: 10.1016/j.scitotenv.2017.02.104. Epub 2017 Feb 21.

Authors

Ivone Vaz-Moreira¹, Olga C Nunes², Célia M Manaia³

Affiliations

¹ Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal; LEPABE, Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal. Electronic address: ivmoreira@porto.ucp.pt.
² LEPABE, Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
³ Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal.

PMID: 28238372
DOI: 10.1016/j.scitotenv.2017.02.104

Abstract

Drinking water comprises a complex microbiota, in part shaped by the disinfection and distribution systems. Gram-negative bacteria, mainly members of the phylum Proteobacteria, represent the most frequent bacteria in drinking water, and their ubiquity and physiological versatility raises questions about possible implications in human health. The first step to address this concern is the identification and characterization of such bacteria that is the first objective of this study, aiming at identifying ubiquitous or persistent Gram-negative bacteria, Proteobacteria or members of other phyla, isolated from tap water or from its source. >1000 bacterial isolates were characterized and identified, and a selected group (n=68) was further analyzed for the minimum inhibitory concentrations (MIC) to antibiotics (amoxicillin and gentamicin) and metals (copper and arsenite). Total DNA extracts of tap water were examined for the presence of putatively acquired antibiotic resistance or related genes (intI1, bla_TEM, qnrS and sul1). The ubiquitous tap water genera comprised Proteobacteria of the class Alpha- (Blastomonas, Brevundimonas, Methylobacterium, Sphingobium, Sphingomonas), Beta- (Acidovorax, Ralstonia) and Gamma- (Acinetobacter and Pseudomonas). Persistent species were members of genera such as Aeromonas, Enterobacter or Dechloromonas. Ralstonia spp. showed the highest MIC values to gentamicin and Acinetobacter spp. to arsenite. The genes intI1, bla_TEM or sul1 were detected, at densities lower than 2.3×10⁵copies/L, 2.4×10⁴copies/L and 4.6×10²copies/L, respectively, in most tap water samples. The presence of some bacterial groups, in particular of Beta- or Gammaproteobacteria (e.g. Ralstonia, Acinetobacter, Pseudomonas) in drinking water may deserve attention given their potential as reservoirs or carriers of resistance or as opportunistic pathogens.

Keywords: Acquired resistance genes; Bacterial diversity; Correlation analysis; Opportunistic pathogens; Tap water safety.

MeSH terms

Drinking Water / microbiology*
Drug Resistance, Bacterial
Gram-Negative Bacteria / isolation & purification*
Microbial Sensitivity Tests
Proteobacteria / isolation & purification*
Water Microbiology*

Substances

Drinking Water