Identification of thermophilic and marine bacilli from shallow thermal vents by restriction analysis of their amplified 16S rDNA

Aims: In order to identify 73 thermophilic isolates from shallow, marine th ermal vents of Eolian Islands, we compared their restriction patterns of am plified 16S rDNA with those of nine well described Bacillus species and eig ht Eolian Bacillus strains. Methods and Results: This study allowed to assign 57 (78%) isolates to diff erent Bacillus species. Nineteen field strains were recognised as represent atives of four described species, namely B. thermodenitrificans, B. caldoly ticus, B. vulcani and B. stearothermophilus. The profiles of 38 isolates ma tched instead, those of seven Eolian strains (B. thermodenitrificans strain A2, B. licheniformis strain B3-15, and five novel species, represented by Bacillus strain lbw, Bacillus strain 4-1, Bacillus strain 5-2, Bacillus str ain 10-1, Bacillus strain las). Among the 16 unidentified isolates, seven r estriction patterns were recognised. Conclusions: This study showed that restriction analysis of amplified 16S r DNA is useful for a rapid and reliable identification of strains belonging to described species as well as for recognition of new species. Significance and Impact of the Study: This work revealed a high taxonomic d iversity among the thermophilic bacilli isolated from Eolian Islands and a distinct distribution of the species within the Eolian hydrothermal vent sy stem.