Heterotrophic plate counts and the isolation of bacteria from mineral waters on selective and enrichment media

M anaia , C.M., N unes , O.C., M orais , P.V. & da C osta , M.S. 1990. Heterotrophic plate counts and the isolation of bacteria from mineral waters on selective and enrichment media. Journal of Applied Bacteriology 69 , 871–876.
The heterotrophic plate counts of 15 brands of bottled non-carbonated mineral waters were examined and found to be generally high and variable. Four selective or enrichment media for the enumeration of coliforms (m-Endo LES and m-lauryl sulphate agar) and Pseudomonas aeruginosa (cetrimide-nalidixic acid agar and malachite green broth) were used to isolate several species of Gram-negative bacteria. Strains identified as CDC gr IVc-2 and Comamonas (Ps.) acidovorans were the two most commonly isolated. Considerable variation in populations was seen between the brands, as well as between two batches of the same mineral water.