Influence of temperature on the growth potential of Southern polar marine bacteria

Regular surveys of heterotrophic microflora from seawater were conducted in the subantarctic (Kerguelen archipelago) and Antarctic (Terre Adélie area). Although a predominance of psychrophilic bacteria could be expected for such polar marine environments, there were no significant differences between results obtained after incubation at two different temperatures (4°C for 21 days or 18°C for 6 days). To investigate this further, four sets of bacterial strains were isolated from the subantarctic area (early fall, late fall, spring, and summer) and one set of Antarctic bacteria was isolated in summer. The growth rates of the 143 strains collected were determined at four different temperatures (4, 7, 20, and 30°C). The results clearly indicated that a large majority of the isolated bacteria must be considered psychrotrophic and not truly psychrophilic strains.