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The study of samples from Antarctica 2008 and 2009 expeditions organized and successfully conducted by
Richard Hoover led to the isolation of diverse anaerobic strains with psychrotolerant and psychrophilic physiology. Due
to the fact that Lake Untersee has never been subject to microbiological study, this work with the samples has significant
and pioneering impact to the knowledge about the biology of this unique ecosystem. Also, the astrobiological
significance for the study of these ecosystems is based on new findings of ice covered water systems on other bodies of
our solar system.
Anaerobic psychrotolerant strain LZ-22 was isolated from a frozen sample of green moss with soils around the
rhizosphere collected near Lake Zub in Antarctica. Morphology of strain LZ-22 was observed to be motile, rod shaped
and spore-forming cells with sizes 1 x 5-10 μm. This new isolate is a mesophile with the maximum temperature of
growth at 40°C. Strain LZ-22 is able to live on media without NaCl and in media with up to 7 % (w/v) NaCl. It is
catalase negative and grows only on sugars with the best growth rate being on lactose. The strain is a neutrophile and
grows between pH 5 and 9.0 with the optimum at 7.8.
Another two strains UL7-96mG and LU-96m7P were isolated from deep water samples of Lake Untersee.
Proteolytic strain LU-96m7P had a truly psychrophilic nature and refused to grow at room temperature. Sugarlytic strain
UL7-96mG was found to be psychrotolerant, but its rate of growth at 3°C was very high compared with other
mesophiles.
Two homoacetogenic psychrophilic strains A7AC-96m and AC-DS7 were isolated and purified from samples
of Lake Untersee; both of them are able to grow chemolithotrophically on H2+CO2. In the presence of lactate, these
strains are able to grow only at 0-18 °C, and growth at 22 °C was observed only with yeast extract stimulation.
In this paper, physiological and morphological characteristics of novel psychrophilic and psychrotolerant
isolates from Antarctica 2008 and 2009 expeditions will be discussed.
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