Genomic and physiological analysis reveals versatile metabolic capacity of deep-sea Photobacterium phosphoreum ANT-2200
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Bacteria of the genus Photobacterium thrive worldwide in oceans and show substantial eco-physiological diversity including free-living, symbiotic and piezophilic life styles. Genomic characteristics underlying this variability across species are poorly understood. Here we carried out genomic and physiological analysis of Photobacterium phosphoreum strain ANT-2200, the first deep-sea luminous bacterium of which the genome has been sequenced. Using optical mapping we updated the genomic data and reassembled it into two chromosomes and a large plasmid. Genomic analysis revealed a versatile energy metabolic potential and physiological analysis confirmed its growth capacity by deriving energy from fermentation of glucose or maltose, by respiration with formate as electron donor and trimethlyamine N-oxide (TMAO), nitrate or fumarate as electron acceptors, or by chemo-organo-heterotrophic growth in rich media. Despite that it was isolated at a site with saturated dissolved oxygen, the ANT-2200 strain possesses four gene clusters coding for typical anaerobic enzymes, the TMAO reductases. Elevated hydrostatic pressure enhances the TMAO reductase activity, mainly due to the increase of isoenzyme TorA1. The high copy number of the TMAO reductase isoenzymes and pressure-enhanced activity might imply a strategy developed by bacteria to adapt to deep-sea habitats where the instant TMAO availability may increase with depth.
KeywordsDeep-sea adaptation Bioluminescence TMAO reductase Hydrostatic pressure Anaerobic respiration
Coding DNA sequence
This work was supported by Grants SIDSSE-201307, SIDSSE-QN-201405, SIDSSE-QN-201406 and SIDSSE-QN-201408 from Sanya Institute of Deep-Sea Sciences and Engineering, the Strategic Priority Research Program grant XDB06010203 and International Partnership for Innovative Team Program (20140491526) from the Chinese Academy of Sciences, the NSFC 41506147 from National Natural Science Foundation of China, a grant for LIA-BioMNSL from Centre National de la Recherche Scientifique, the grant DY125-15-R-03 from China Ocean Mineral Resources R & D Association (COMRA) Special Foundation, the Grant NSFC 41306161 from the National Science Foundation of China and a grant from Mt. Tai Scholar Construction Engineering Special Foundation of Shandong Province. We acknowledge France Genomique for the support for this sequencing project.