Microbiological safety of natural mineral water

FEMS Microbiology Reviews 26 (2002) 207^222 www.fems-microbiology.org Microbiological safety of natural mineral water Henri Leclerc a a; b , Annick Moreau Faculte¤ de Me¤decine de Lille et Institut Pasteur de Lille, 1 place de Verdun, 59045 Lille Cedex, France b Centre Expertise Eau/Danone, P.O. Box 87, 74500 Evian les Bains, France First published online 24 April 2002 Abstract Natural mineral water originates from groundwater, an oligotrophic ecosystem where the level of organic matter is low and of a very limited bioavailability. The bacterial populations that evolve in these ecosystems are heterotrophic and in starvation^survival state resulting from an insufficient amount of nutrients; for this reason they enter a viable but non-culturable state. After bottling, the number of viable counts increases rapidly, attaining 104 ^105 colony-forming units ml31 within 3^7 days. These bacterial communities, identified by culture or with specific probes, are primarily aerobic, saprophytic, Gram-negative rods. Groundwater sources for natural mineral waters are selected such that they are not vulnerable to fecal contamination. Ecological data, especially the diversity and physiological properties of bacterial communities, are essential together with epidemiological studies in order to perform a risk analysis for natural mineral waters. On a continuing basis, the management of microbial risks has to rely on assessment of the heterotrophic plate count and, more specially, on detection of marker organisms, i.e. the classic fecal contamination indicators that have to be absent, and vulnerability indicators for which the occurrence should be as low as possible. It is also recommended to search regularly, but not routinely, for viral and protozoan pathogens. 2 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved. Keywords : Natural mineral water; Risk assessment; Indicator of fecal contamination ; Starvation^survival; Waterborne disease; Viable but non-culturable bacterium Contents 1. 2. 3. 4. 5. 6. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Groundwater habitat . . . . . . . . . . . . . . . . . . . . . . . 2.1. Biological component . . . . . . . . . . . . . . . . . . . Starvation^survival lifestyle . . . . . . . . . . . . . . . . . . 3.1. The viable but non-culturable (VBNC) state . . Bottle habitat . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. The bottle e¡ect . . . . . . . . . . . . . . . . . . . . . . . 4.2. Other factors . . . . . . . . . . . . . . . . . . . . . . . . . 4.3. Growth or resuscitation . . . . . . . . . . . . . . . . . Microbial community . . . . . . . . . . . . . . . . . . . . . . 5.1. Prosthecate bacteria . . . . . . . . . . . . . . . . . . . . 5.2. Pseudomonas, Acinetobacter, Alcaligenes . . . . . . 5.3. Cytophaga, Flavobacterium, Flexibacter . . . . . . 5.4. Gram-positive bacteria . . . . . . . . . . . . . . . . . . 5.5. Microbial diversity and speci¢city . . . . . . . . . . Assessing health risks from autochthonous bacteria 6.1. Animal model system . . . . . . . . . . . . . . . . . . . 6.2. Randomized trial in infants . . . . . . . . . . . . . . . 6.3. Virulence characteristics of bacteria . . . . . . . . . * Corresponding author. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208 208 208 209 210 211 211 212 212 213 214 214 214 214 215 215 215 215 216 E-mail address: (H. Leclerc). 0168-6445 / 02 / $22.00 2 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved. PII : S 0 1 6 8 - 6 4 4 5 ( 0 2 ) 0 0 0 9 7 - 9 FEMSRE 747 10-6-02 Received 12 November 2001; received in revised form 6 February 2002; accepted 8 February 2002 208 H. Leclerc, A. Moreau / FEMS Microbiology Reviews 26 (2002) 207^222 7. . . . . . . 216 216 216 217 217 220 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 8. Assessment and management of microbial health risks . . . . . . . 7.1. Identifying microbial hazards in drinking water . . . . . . . . . 7.2. Concerning certain characteristics of natural mineral water 7.3. Assessment of microbial risks . . . . . . . . . . . . . . . . . . . . . . 7.4. Management of microbial risks . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. Introduction 2. Groundwater habitat Before the 1970s, the study of life in groundwater habitats was relatively limited. In the 1970s, however, it became increasingly obvious that certain waste disposal practices were contaminating subsurface environments with e¡ects on groundwater quality. This led to the current interest in the study of these environments. There has also been an increasing interest in demonstrating that various shallow and deep environments contain substantial numbers of viable microorganisms and in using the ability of these microorganisms to degrade potential pollutants, i.e. in bioremediation. Subsurface microbiological research to study microbial community structure, microbial activities and the geochemical properties of groundwater environments has progressed with the development of aseptic sampling techniques [1,2]. In a hydrogeological sense, groundwater refers to water that is easily extractable from saturated, highly permeable strata known as aquifers. For saturated environments, a rigorous distinction between local, intermediate, and re- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gional £ow systems, related to the topography of recharge and discharge areas, has been long recognized by hydrol (...truncated)