Affiliation:
1. Danish Institute for Fisheries Research, Department of Seafood Research, Technical University of Denmark, DK-2800 Lyngby,1 and
2. Enzyme Development, Novo Nordisk, DK-2880 Bagsværd,2 Denmark
Abstract
ABSTRACT
The marine bacterium
Shewanella algae
, which was identified as the cause of human cases of bacteremia and ear infections in Denmark in the summers of 1994 and 1995, was detected in seawater only during the months (July, August, September, and October) when the water temperature was above 13°C. The bacterium is a typical mesophilic organism, and model experiments were conducted to elucidate the fate of the organism under cold and nutrient-limited conditions. The culturable count of
S. algae
decreased rapidly from 10
7
CFU/ml to 10
1
CFU/ml in approximately 1 month when cells grown at 20 to 37°C were exposed to cold (2°C) seawater. In contrast, the culturable count of cells exposed to warmer seawater (10 to 25°C) remained constant. Allowing the bacterium a transition period in seawater at 20°C before exposure to the 2°C seawater resulted in 100% survival over a period of 1 to 2 months. The cold protection offered by this transition (starvation) probably explains the ability of the organism to persist in Danish seawater despite very low (0 to 1°C) winter water temperatures. The culturable counts of samples kept at 2°C increased to 10
5
to 10
7
CFU/ml at room temperature. Most probable number analysis showed this result to be due to regrowth rather than resuscitation. It was hypothesized that
S. algae
would survive cold exposure better if in the biofilm state; however, culturable counts from
S. algae
biofilms decreased as rapidly as did counts of planktonic cells.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
32 articles.
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