Microbial quality and nutritional aspects of Norwegian brand waters

Abstract

The microbiological quality of the five leading brands of Norwegian bottled still waters was investigated. All brands were free for the enteric indicator organisms and named pathogens whose absence is demanded in current quality directives. The relatively nutrient-poor agar R₂A revealed large heterogeneous bacterial populations which grew slowly, or not at all, on clinical media specified for use in substrate-utilization approaches to identification. The main approach used for identification was cultivation of microbes on R₂A, followed by amplification and partial sequencing of 16S rDNA genes. The identity of the heterotrophic plate count of the brands differed significantly to that found in many other similar studies with respect to the dominating species. The bacterial flora was dominated by beta- and alphaproteobacteria most of which were psychrotolerant. Several brands contained Sphingomonas and large populations of Methylobacterium species which have been associated with a variety of opportunistic infections of immunocompromised hosts. Analysis of the isolated strains' nutritional capabilities using the Biolog GN2® system, gave in most instances low positive scores, and strain identifications using the system were generally inconclusive. Measures of assimilable organic carbon in the water revealed that some brands contained levels higher than those which have been associated with biological stability and restricted or no growth of heterotrophs in distribution systems. The relationship between assimilable organic carbon and R₂A plate counts was significant and moderately positive for bottled waters. Assimilable organic carbon correlated strongly with the survival time of Escherichia coli when introduced into bottles as a contaminant. Those brands having high values (~100 μg/L) supported protracted survival, but not growth of E. coli, whereas E. coli quickly became nonculturable in brands with low values. Thus measures of assimilable organic carbon may have a particular value in predicting the survival of this and nutritionally similar species of hygienic relevance. Only small numbers of fungi were found. However, one isolate (Aureobasidium pullulans) has been associated with infections of humans.

Treatment stage associated changes in cellular and molecular microbial markers during the production of drinking water at the Vansjø water works

“…Bacteria were identified by partial sequencing of the 16S rRNA gene exactly as previously described (Otterholt and Charnock, 2011a) using the primers 341f and 907f and a small amount of colony material as template. Sequencing reactions were performed by a commercial laboratory (ABI-lab, University of Oslo, Oslo, Norway) using the PCR primers.…”

“…The reported count includes only confirmed yeasts and molds. A forward primer binding to 3 0 -end of 18S rDNA and a reverse primer binding to the 5 0 -end of 25/28S rDNA of yeasts were used to amplify the intervening 5.8S gene and the noncoding Internal Transcribed Spacer regions ITS1 and ITS2, exactly as previously described (Otterholt and Charnock, 2011a). Sequencing reactions were performed using the PCR primers.…”

Evaluation of preservative efficacy in pharmaceutical products: the use of psychrotolerant, low-nutrient preferring microbes in challenge tests

“…Abbreviated to S sp. 2 The Sphingomonadaceae (Alphaproteobacteria) form part of a recently published large‐scale identification of the bacterial flora of Norwegian drinking waters 13 and have accession numbers HQ601937 ( S sp.1) and HQ601940 ( S sp.2). Strains C. t and C. l (a Betaproteobacterium) are new to this study and have the accession numbers (JF766377 and JF766378).…”

“…PCR amplification and sequencing of the 5.8S gene and the non‐coding Internal Transcribed Spacer regions ITS1 and ITS2 were performed exactly as previously described 13 . Similarity searches were performed as described above for bacteria.…”

“…Identification of bacteria based on colony-polymerase chain reaction (PCR) of the 16S rRNA gene PCR amplification and sequencing of approximately 500 bp of a segment of the 16S rRNA gene were performed exactly as previously described. 13 Sequence similarity searches were conducted in April 2012 using the blast network service and the GenBank database.…”