GENOMIC TYPING AND FATTY-ACID COMPOSITION OF RHODOTHERMUS-MARINUS

Twenty strains of Rhodothermus marinus from shallow marine hot springs in Iceland, the Is. of S. Miguel in the Azores and the Stufe di Neron e, Naples, Italy and one spontaneous non-pigmented variant were examin ed by pulsed-field gel electrophoresis (PFGE), restriction fragment le ngth polymorphism of the rRNA genes (ribotyping) and fatty acid analys is. Whole genome DNA-DNA hybridization showed that strains PRQ-36, PRQ -40 and PRQ-52 from the Azores and strain NR-29 from Naples shared a h igh DNA homology with the type strain (DSM 4252(T)) from Iceland that range between 77% and 89% and, therefore, belong to the same genomic s pecies. The fatty acid composition of all the strains was very similar , indicating a close relationship of the strains, as well. The PFGE an alysis using AseI and PmeI generated distinct electrophoretic patterns for most strains. However, some strains from the Azores had identical PFGE patterns and probably represented clones of the same organism. T he inferred genomic size of the strains varied between about 3.3 and 3 .6 megabase pairs (Mbp), except for one strain with an estimated genom ic size of 2.8 Mbp. Ribotyping with EcoRI, PstI, BamHI and HindIII pro duced several distinct ribotypes that generally shared one or more ban ds in common. The ribotypes establish a basis for a typing system for these Bacteria.