New psychrophilic and psychrotolerant Bacillus marinus strains from tropical and polar deep-sea sediments and emended description of the species.

In contrast to the current view that psychrophily combined with an absolute requirement for NaCl is connected with the Gram-negative cell wall type, psychrophilic and psychrotolerant, NaCl-requiring, Gram-positive bacteria have been isolated from tropical Atlantic, Arctic and Antarctic deep-sea sediments. Some of the isolates are even extremely psychrophilic, having maximum growth temperatures of 4 degrees C. On the basis of phenotypic characteristics, DNA base analyses, DNA-DNA hybridizations and partial and complete 16S rRNA gene sequence analyses, the strains from the three distinct geographical regions have been allocated to the obligately marine species Bacillus marinus. The distribution and origin of B. marinus are discussed and an emended description of the species is presented.