Abstract
The organisms from heterotrophic plate counts of four brands of bottled non‐carbonated mineral waters were analysed by ribosomal ribonucleic acid gene restriction patterns in addition to identification by customary techniques. Five commercialized bottles of each brand were examined once in the year 1989–90. The total bacterial flora was divided into two main groups: the pseudomonads and the unidentified strains. Whereas phenotypic results did not reveal any significant differences between the four brands, rRNA gene restriction patterns were discriminatory. Among the 73 strains studied, 45 distinct patterns were observed, with only three common to several springs. These results reveal, at one determined time, a remarkable biological specificity of each brand of water.