A NEW IRON-OXIDIZING BACTERIUM, LEPTOSPIRILLUM-THERMOFERROOXIDANS SP-NOV

A new aerobic thermoacidophilic, chemolithoautotrophic, iron-oxidizing bacteria with important phenotypic similarities to Leptospirillum fer rooxidans was isolated from acid iron-containing hydrothermal springs (pH approximately 2, approximately 45-degrees-C) on the island of Kuna shir (Kuril Islands). The temperature characteristics of the new bacte rium differed from those of Leptospirillum ferrooxidans. in having an optimal temperature of 45-50-degrees-C and a maximum temperature of 55 -60-degrees-C, and by its greater resistance to high Fe2+ concentratio ns. The optimal pH for growth was 1.65-1.9. The GC content in the ther mophilic strain L-88 was 56.2 +/- 0.3 mol.%, which was some six units greater than that of the mesophilic type strain of Leptospirillum ferr ooxidans. VKM B-1339, which was 50.3 +/- 0.3 mol.%. The level of DNA h omology between Leptospirillum ferrooxidans and Leptospirillum thermof erroxidans was 26.7%. On the basis of these phenotypic and genotypic d ifferences, strain L-88 is presented as a new species of the genus Lep tospirillum, with the name Leptospirillum ferrooxidans species. nov. S train L-88 is kept at the Institute of Microbiology (INMI) of the Russ ian Academy of Sciences.