In the present study, we report the whole genome sequences of two species, Ornithinibacillus contaminans DSM22953 T isolated from human blood and Ornithinibacillus californiensis DSM 16628 T isolated from marine sediment, in genus Ornithinibacillus . Comparative genomic study of the two species was conducted together with their close relative Ornithinibacillus scapharcae TW25 T , a putative pathogenic bacteria isolated from dead ark clam. The comparisons showed O. contaminans DSM22953 T had the smallest genome size of the three species indicating that it has a relatively more stable habitat. More stress response and heavy metal resistance genes were found in the genome of O. californiensis DSM 16628 T reflecting its adaption to the complex marine environment. O. scapharcae TW25 T contained more antibiotic resistance genes and virus factors in the genome than the other two species, which revealed its pathogen potential. [ABSTRACT FROM AUTHOR]