tranquillimonas tranquillimonas tranquillimonas is a gram-negative, obligately halophilic, rod-shaped and non-motile genus of bacteria from the family of rhodobacteraceae with one known species (tranquillimonas alkanivorans). tranquillimonas alkanivorans has been isolated from seawater from the semarang port in indonesia. tranquillimonas scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: rhodobacterales family: rhodobacteraceae genus: tranquillimonasharwati et al. 2008 type species tranquillimonas alkanivorans species t. alkanivorans