Alicyclobacilli from an Unexplored Geothermal Soil in Antarctica: Mount Rittmann
Barbara NICOLAUS*, Roverta IMPROTA, M. Cristina MANCA, Licia LAMA, Enrico ESPOSITO, and Agata GAMBACORTA
Instituto per la Chimica di Moledole di Interesse Biologico, CNR, via Toiano 6, 80072 Arco Felice, Napoli, Italy
Temperature is one of the most important environmental variables; the classification of living organisms based on their relation to temperature has always been considered one of the most basic elements of biological systematics. Many prokaryotes that can grow above the thermophile boundary of 55 to 60℃, indicating considerable diversity (1). The ecology of thermophilic bacteria is, in many respects, more complicated than that of thermophilic Archaea, since there is more diversity both in respect to metabolism and habitats.
Within Antarctic continent there are geothermal environments on Mount Melbourne, Mount Erebus and Mount Rittmann. For the first time, during the antarctic summer 1993-1994, it was possible to reach and then collect samples to study the microbiota present in the geothermal soil at a temperature of approximately 60℃ (2,3). The isolation of three species from soil samples from an unexplored site in Antarctica, belonging to Alicyclobacillus genus was reported. The isolates, named MR1, MR2 and MR4 were from 30 samples of geothermal soil from Mount Rittmann. All the isolates had lipids based mainly on fatty acids possessing a terminal cyclohexane, components of each 'FAME fraction were identified by NMR, GLC and GC-MS; hopanoid and quinones of MK-7 were also present. All isolates were characterized by phenotypic features and the isolate MR1 was subjected to genetic analyses. The isolates were thermoacidophilic showing an optimum temperature of 63℃ and an optimum pH of 3.5-4.0. They were able to grow in the temperature range 45-70℃. The % G+C of DNA of MR1 was 64.9% and showed a 16S rDNA similarity of 99.3% with Alicyclobacillus acidocaldarius ATCC 43034 and a DNA- DNA homology of 69.7% with A. acidocaldarius DSM 446. The proposed to accommodate MR1 in the genus Alicyclobacillus as subspecies rittmannii of A. acidocaldarius.
This research is within the framework of the Italian National Programme for Antarctic Research.
1. Kristjansson, J.K. and Stetter, K.O. (1992) In: Thermophilic Bacteria, J.K. Kristjansson, Ed.CRC Press, Boca Raton, 1-18.
2. Nicolaus, B., Manca, M.C., Lama, L., Esposito, E., and Gambacotta, A. (1995), System. Appl. Microbiol., 18, 32-36.
3. Nicolaus, B., Lama, L., Esposito, E., Manca, M.C., di Prisco, G., and Gambacotta, A. (1996) Polar Biol., 16, 101-104.
