A novel proterhodopsin bearing Flavobacterium species from an Antarctic saline lake

Numerous Flavobacterium species have been officially described from Antarctic samples, and with recent investigations more will likely be described [1]. All Antarctic Flavobacterium species show some level of cold adaptation and have enhanced osmotolerance relative to other members of Flavobacterium (Fig. 1). 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, however most species cluster together suggesting ecophysiological specialisation amongst related Flavobacterium species. Within the largest of these cold-adapted clades (Fig. 2) resides one so far undescribed strain, designated ACAM 123, most closely related to the species F. degerlachei and F. frigoris. ACAM 123 likely represents a novel species, based on accumulated data [2]. ACAM 123 is both salt-requiring and psychrophilic (tolerates up to 6% NaCl, optimal temperature for growth ~10°C). ACAM 123 forms slimy orange colonies and contains carotenoids but not flexirubin pigments. The strain is not motile (or only weakly so at best) and is also non-fermentative, proteolytic, moderately saccharolytic and able to perform assimilatory denitrification, via reduction of nitrate to ammonia.