ALICYCLOBACILLI FROM AN UNEXPLORED GEOTHERMAL SOIL IN ANTARCTICA - MOUNT-RITTMANN

The isolation of three species from soil samples from an unexplored si te in Antarctica, belonging to the Alicyclobacillus genus, is reported . The isolates, named MR1, MR2 and MR4, were from 30 samples of geothe rmal soil from Mount Rittmann. All the isolates had lipids based mainl y on fatty acids possessing a terminal cyclohexane; hopanoid and quino nes of MK-7 were also present. All isolates were characterized by phen otypic features and the isolate MR1 was subjected to genetic analyses. The isolates were thermoacidophilic, showing an optimum temperature o f 63 degrees C and an optimum pH of 3.5-4.0. They were able to grow in the temperature range 45-70 degrees C. The percentage C+G of DNA of M R1 was 64.9% and showed a 16S rDNA similarity of 99.3% with Alicycloba cillus acidocaldarius ATCC 43034 and a DNA-DNA homology of 69.7% with A. acidocaldarius DSM 446. The strain MR1 is unable to produce amyloly tic activity under different growth conditions. It is proposed to acco mmodate MR1 in the genus Alicyclobacillus as subspecies rittmannii of A. acidocaldarius.