Heterotrophic bacterial populations in the mineral waters of thermal springs in Spain

摘要

The microbiological quality and heterotrophic bacterial populations of 26 thermal mineral water springs in Spain were studied. In most of the springs the number of viable aerobes was less than 103cfu ml‐1and the number of sporulated bacteria less than 102cfu ml‐1. No significant differences were foundin the counts obtained with Plate Count Agar (PCA) and PCA diluted 1 : 10 and incubated at 22°, 37° and 45°C. Total coliforms were found in 14 springs, faecal streptococci in three, spores of sulphite‐reducingClostridiumandPseudomonas aeruginosain seven. NeitherEscherichia colinorStaphylococcus aureuswere found. A total of 665 strains were isolated and 85·4 of these identified; 329 were Gram‐positive and 239 were Gram‐negative. The genera most prevalent present in the springs werePseudomonas(in 92.3),Bacillus(65.4),Enterobacter, MicrococcusandStaphylococcus(50),Acinetobacter(42.3),Arthrobacter(38.4),Clostridium(27) andXanthomonas(23). Gram‐negative bacteria predominated in the mesothermal springs and Gram‐positive bacteria in the hyper‐ and hypothermal springs. The most common Gram‐negative rod species isolated werePs. fluorescens, Ps. aeruginosa, Ps. putida, Ent. agglomerans, Ent. sakazakii, Ac. calcoacet