From Genomics to Physiology: Identification and Characterization of Discovered Cyclobacterium marinum (07MW18)

Cyclobacterium, a member of the Bacteroidetes phylum, is of great interest due to their tremendous genetic diversity and might play a role in the degradation of biopolymers and particulate detritus. It has been established that the majority of oceans are oligotrophic and availability of detritus in the dark ocean varies throughout the year. Here we report the cultivation of a rare bacterium, Cyclobacterium marinum, from the Atlantic slope at a depth of 260 meters and presume it to be a conditional copiotroph. We are using the genomic and traditional approach to determine its biochemical potential as a conditional oligotrophic marine bacteria. The preliminary data suggest Cyclobacterium is capable of growing in hypersaline environment up to 120 ppt NaCl. The doubling time for Cyclobacterium in Complete Sea Water medium is 23.9 hours, and in the low nutrient environment is 82.84 hours. Cyclobacterium was able to utilize complex carbohydrates and was not able to utilize glucose, sucrose, xylose, galactose, lactose, maltose, and mannitol. The carbohydrate utilization experiment will be repeated for further validation, along with additional complex carbohydrates. We are also exploring the metabolic potential using the genomic approach. The metabolic modeling using whole-genome sequence data suggest that 07MW18 has pathways to use bicarbonate as inorganic C- source. It has three copies of bicarbonate transporter (BicA) and two copies of Carbonic Anhydrase gene. We hypothesize that in the oligotrophic environment, Cyclobacterium will adapt to utilizing bicarbonate as ‘C’ source. For this, we will culture Cyclobacterium in oligotrophic media supplemented with bicarbonate and analyzing expression of BicA and CA genes.