Adaptive Changes in the Inferred Proteomes of Dominant Bacterial Clades in the Global Ocean

Using a global metagenomic dataset of marine bacterial nucleotide sequences as part of the Ocean Sampling Day Consortium, I identified sequences belonging to the most abundant clades of marine bacteria on a global scale. When translated to protein sequences and compared against protein domain databases, these proteomes show that marine bacteria have distinct adaptations to local conditions, based on temperature, salinity, and latitude (perhaps a proxy for insolation). These adaptations are distributed throughout the proteome, but protein domains associated with central metabolic and housekeeping functions are more likely to have adaptations than others. The most common clades, Prochlorococcus spp. and Pelagibacter spp., showed less adaptation to local environments than did less common clades like Sulfitobacter and Flavobacterium.