Cold-active acetogenic bacteria in the permanently cold sediments of Lake Fryxell, Antarctica were investigated using culture-based methods. Two psychrophilic, acetogenic strains were isolated and found to be physiologically and phylogenetically related to Acetobacterium bakii and Acetobacterium tundrae. However, the Antarctic isolates showed a lower growth temperature range than other species of Acetobacterium, with growth occurring from -2.5 to 25 degrees C and optimally at 19-21 degrees C. Cultures incubated at +5 and +1 degrees C grew with generation times of 7 and 9 days, respectively. The rapid growth of these strains at low temperatures suggests that acetogenesis may be an important anaerobic process in the sediments of Lake Fryxell.
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