Bacterial flora in bottled uncarbonated mineral drinking water

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Abstract
A quantitative study of bacterial populations in mineral water was carried out. Samples were stored at 6 and 20.degree. C, and the colony counts were determined on tryptone agar plates incubated at 22 and 37.degree. C. Samples were collected from the spring source in sterile glass flasks and from the bottling factory in conventional plastic and glass containers. In both cases, the initial population (101-102 cfu/mL water) increased to 105-106 cfu/mL after 3 days storage as determined from plate counts incubated at 22.degree. C. The levels reached by this population were similar to those of samples of mineral water obtained at the market stage. Results from plate counts incubated at 37.degree. C showed that populations in samples collected at the bottling factory reached 102-103 cfu/mL. No growth was observed in water collected from spring source. Bacterial multiplication was not stopped even when water was stored at 6.degree. C. Caulobacter was the genus found most frequently in both types of samples, followed by Sphaerotilus-Leptothrix. Acinetobacter calcoaceticus and Pseudomonas fluorescens were frequently found in only two wsprings, and Pseudomonas putida, Arthrobacter, Aeromonas hydrophila, and Corynebacterium were isolated less frequently. Janthinobacterium was recovered only once from a single spring. A giant bacterium closely resembling Hyphomicrobium and a budding one similar to Pasteuria were recovered from all samples of a single spring and from some of the commercial samples.