A novel light stimulated Flavobacterium species from an Antarctic saline lake

Flavobacterium species have been detected and isolated in various polar biomes, predominantly freshwater to marine salinity Antarctica continental lakes. So far 16 species have been officially described. All species show some level of cold adaptation and have comparatively enhanced osmotolerance relative to other members of the genus. The overall pattern of the distribution of cold-adapted species within the Flavobacterium phylogenetic radiation suggests the emergence of cold adaptation has occurred multiple times within different ecosystems over the least 0.5-0.7 Gya. One so far undescribed strain ACAM 123, most closely related to F. degerlachei, and likely representing a novel species represents one such emerged cold adapted lineage being both salt-requiring and very psychrophilic (opt. temp. ~10°C). ACAM 123 is non-fermentative, proteolytic, able to denitrify, and appears to be epiphytic in nature. It was isolated from Burton Lake a meromictic lagoon located within the Vestfold Hills ice free zone of Antarctica. This water body has an unusually high Bacteroidetes diversity. Most interestingly we can show the growth yield, metabolic rate, ATP content and carotenoid pigment content of ACAM 123 is stimulated by light, linked to its possession of a proteorhodopsin system. The genome of ACAM 123 was obtained by 454 pyrotag sequencing in order to reveal traits related to its response to illumination. ACAM 123 contains numerous putative bacteriophytochrome signal transduction systems further suggesting light is influential on its growth. The overall results suggests Flavobacterium species have not only successfully adapted to cold ecosystems but species can be econiche specialists that bear superficially little resemblance to the ecological preferences of the more well studied species of Flavobacterium.