Candidatus Pelagibacter communis

Candidatus Pelagibacter communis

Candidatus Pelagibacter communis

Candidatus Pelagibacter communis is a species of bacteria that belongs to the SAR11 clade, one of the most abundant groups of microorganisms in the ocean. This bacterium is a member of the Alphaproteobacteria class and is known for its small size and streamlined genome.

Characteristics

Candidatus Pelagibacter communis is characterized by its extremely small cell size, typically around 0.37 micrometers in diameter. It has a highly reduced genome, which is one of the smallest known for any free-living organism, consisting of approximately 1.3 million base pairs. This streamlined genome reflects its adaptation to the nutrient-poor environments of the open ocean.

Ecology

Candidatus Pelagibacter communis is found throughout the world's oceans, from the surface to depths of several hundred meters. It plays a crucial role in the marine carbon cycle by consuming dissolved organic carbon and releasing carbon dioxide through respiration. This process is vital for the recycling of carbon in marine ecosystems.

Metabolism

The metabolism of Candidatus Pelagibacter communis is adapted to the oligotrophic conditions of the open ocean. It relies on the uptake of simple organic compounds, such as amino acids and dimethylsulfoniopropionate (DMSP), for energy and growth. The bacterium is also capable of photoheterotrophy, using light to supplement its energy needs through the use of a proteorhodopsin protein.

Genomic Features

The genome of Candidatus Pelagibacter communis is notable for its high coding density, with very few non-coding regions. It lacks many of the genes typically found in other bacteria, such as those for biosynthesis of certain amino acids and vitamins, which it must obtain from its environment. This minimalistic genome is a result of evolutionary pressure to maintain efficiency in nutrient-poor environments.

Importance in Marine Ecosystems

Candidatus Pelagibacter communis is a key player in the biogeochemical cycles of the ocean. By processing dissolved organic matter, it helps maintain the balance of carbon and other nutrients in marine ecosystems. Its abundance and activity make it a significant contributor to the global carbon cycle and climate regulation.

Related Pages

• SAR11 clade
• Marine carbon cycle
• Alphaproteobacteria
• Photoheterotrophy