Polaribacter

P. aestuariivivens[1] P. aquimarinus[1] P. atrinae[1] P. butkevichii[1] P. dokdonensis[1] P. filamentus[1] P. franzmannii[1] P. gangjinensis[1] P. glomeratus[1] P. haliotis[1] P. huanghezhanensis[1] P. insulae[1] P. irgensii[1] P. lacunae[1] P. litorisediminis[1] P. marinaquae[1] P. marinivivus[1] P. pacificus[1] P. porphyrae[1] P. reichenbachii[1] P. sejongensis[1] P. septentrionalilitoris[1] P. staleyi[1] P. tangerinus[1] P. undariae[1] P. vadi[1] Polaribacter is a genus in the family Flavobacteriaceae.

[5] Members of the genus Polaribacter decompose algal cells and thus may be important in biogeochemical cycling, as well as influence seawater chemistry and the composition of microbial communities as temperatures continue to rise.

[6] Polaribacter is a genus that is being continuously researched and to date there are 25 species that have been validly published under the International Code of Nomenclature of Prokaryotes (ICNP): P. aquimarinus, P. atrinae, P. butkevichii, P. dokdonensis, P. filamentus, P. franzmannii, P. gangjinensis, P. glomeratus, P. haliotis, P. huanghezhanensis, P. insulae, P. irgensii, P. lacunae, P. litorisediminis, P. marinaquae, P. marinivivus, P. pacificus, P. porphyrae, P. reichenbachii, P. sejongensis, P. septentrionalilitoris, P. staleyi, P. tangerinus, P. undariae, P. vadi.

[8] P. huanghezhanensis P. porphyrae P. marinivivus P. aquimarinus P. gangjinensis P. reichenbachii P. marinaquae P. dokdonensis P.sp.MED152 P. insulae P. vadi P. litorisediminis P. haliotis P. tangerinus P. atrinae P. butkevichii P. undariae P. sejongensis P. irgensii P. franzmannii P. filamentus P. glomeratus Tenacibaculum Members in the genus Polaribacter are abundant in polar oceans and are important in the export of dissolved organic matter (DOM).

The Antarctic spring is especially important as it brings about significant changes, including sea ice melting, thermal stratification due to warming surface waters, and increased dissolved organic matter (DOM) production.

[23] The relative abundance of free-living bacteria belonging to the genus Polaribacter and in the family Rhodobacteraceae peaked at different points during phytoplankton blooms, suggesting a niche specialization contributing to successive degradation of phytoplankton-derived organic matter.

[23] For both the Arctic Ocean and the North Sea, Polaribacter exhibited similar trends pertaining to phytoplankton blooms in the summertime as well as assuming particular niches for organic matter degradation.

[17] Many research studies have found that Polaribacter can alternate between two lifestyles as a mechanism for adaptation in surface waters where nutrient concentrations are low and light exposure is high.

[4] Sequenced strains of the genus Polaribacter show a high prevalence of peptidase and glycoside hydrolase genes in comparison to other bacteria in the Flavobacteriaceae, indicating they contribute to degradation and uptake of external proteins and oligopeptides.

[17] Once they've degraded these molecules, the bacterium may then search for new particles to colonize, forcing them to freely-swim in environments where nutrients and organic carbon is not easily available.

[27][28] Some notable features of the genome include genes for agar, alginate, and carrageenan degrading enzymes in Polaribacter species which colonize the surface of macroalgae.

[27][29] Proteases are also commonly found in the genomes of species that preferentially grow on solid substrates and degrade protein instead of using free amino acids and living a pelagic lifestyle.

[29][4] A genomic analysis of the Polaribacter strain MED152, found a considerable amount of genes that allow for surface or particle attachment, gliding motility and polymer degradation.

[4] This led the researchers to theorize that Polaribacter strain MED152 has two different life strategies, one where it acts like other marine bacteroidetes, attaching to surfaces and searching for nutrients and, another life strategy where, if the strain was in a well lit, low nutrient area of the ocean, it would use carbon fixation to synthesize intermediates of metabolic pathways.

The strain Hel1_33_49 has a genome which contains proteorhodopsin, fewer polysaccharide utilization loci and no mannitol dehydrogenase, which the researchers associate with a pelagic lifestyle.

[17] Hel1_85 on the other hand, has a genome which contains twice as many polysaccharide utilization loci, a mannitol dehydrogenase and no proteorhodopsin, pointing to a lifestyle with lower oxygen availability such as a biofilm.

[17] Only two species of lytic phage are known to infect members of this genus, and both have double stranded DNA with virions that include isometric heads and non-contractile tails (class Caudoviricetes, morphotype: siphoviruses).

These cold dwelling bacteria are an abundant source of psychrophilic enzymes which have an interesting ability to retain higher catalytic activity at temperatures below 25 °C.

[36] This is important as enzymes that operate at lower temperatures not only make the industrial processes more efficient, but they also minimize the chance of side reactions occurring.

Psychrophilic enzymes can also aid with heat labile or volatile compounds, allowing reactions to occur without significant product loss.