La flore bactérienne des eaux thermales et minérales

Bacterial flora in thermal and mineral waters

Université de Bordeaux 2, Laboratoire de Microbiologie Pharmaceutique

Abstract

Mineral and thermal waters are not sterile, but contain an indigenous microbial flora of a kind related to the physical and chemical characteristics of these biotopes.

This microflora can be divided into two groups on a metabolic basis: first, lithotrophic bacteria which draw their energy from inorganic substances, and secondly organotrophic bacteria which use organic matter. The former play an important role in the cycle of elements such as sulphur and iron, and in the formulation of certain thermal compounds such as glairins, but have been little studied owing to the slowness of their growth on synthetic media. The second group, which can be demonstrated by simple and rapid methods of culture, consist essentially of gram-negative bacilli (Pseudomonas, Xanthomonas, Acinetobacter, etc.) and show high numerical stability with time. They have no health significance but any sudden rise in their number can indicate contamination of the resource.

Better knowledge of these two types of bacterial flora could make it possible to select biological identity markers from the species characteristic of the resource and lead to a better understanding of their role in the operation of this natural ecosystem.