Bacteriological Quality of Noncarbonated Mineral Water

GERMÁN ALEJANDRO MESSINA; VELAZQUEZ LIDIA; MARIA E. ESCUDERO; ANA M.S. DE GUZMÁN

Mendoza, Argentina.

Congreso; Cuyo Biology Society. 16 Annual Scientific Meeting; 1999

The presence of Pseudomonas sp in noncarbonated mineral water was investigated. Ten samples purchased in retail stores in San Luis were analyzed by: 1) spread plate method (SPM) and 2) membrane filter technique (MFT) after concentration 250 ml-volumes. Three plating media were used: plate count agar (PCA), Aeromonas Pseudomonas agar(GSP), and Pseudomonas selective agar (PS). They were incubated during 72 h at 25°C. In PCA, 495 to 19278 cfu/ml were counted using SPM and massive growth was observed by MFT; in GSP no growth was observed by SPM but 11 to 643 cfu/250 ml were counted by MFT. Similarly, in PS negative results were observed by SPM and 0 to 112 cfu/250 ml were obtained by MFT. Colonies showed morphological, biochemical and staining characteristics of Pseudomonas genus. The microorganisms were motile gram-negative rods, positive for oxidase, catalase and arginine tests and negative for nitratase assay. The Argentine Food Code states that noncarbonated mineral water must not contain P. aeruginosa in a 250 ml sample.