Strain AB-CW3, a Proteolytic Bacterium From Hypersaline Soda Lakes That Preys on Cells of Gram-Positive Bacteria.

A new haloalkaliphilic species of , strain AB-CW3, was isolated from a system of hypersaline alkaline soda lakes in the Kulunda Steppe using cells of as growth substrate. AB-CW3's complete, circular genome was assembled from combined nanopore and Illumina sequencing and its proteome was determined for three different experimental conditions. AB-CW3 is an aerobic gammaproteobacterium feeding mainly on proteins and peptides. Unique among , it uses a flagellum for motility, fimbria for cell attachment and is capable of complete denitrification. AB-CW3 can use proteins derived from living or dead cells of and other Gram-positive bacteria as the carbon and energy source. It encodes and expresses production of a novel Lantibiotic, a class of antimicrobial peptides which have so far only been found to be produced by Gram-positive bacteria. AB-CW3 likely excretes this peptide via a type I secretion system encoded upstream of the genes for production of the Lanthipeptide. Comparison of AB-CW3's genome to 18 other genomes from marine, hypersaline, and soda lake habitats indicated one or two transitions from marine to soda lake environments followed by a transition of back to the oceans. Only 19 genes appear to set haloalkaliphilic apart from their neutrophilic relatives. As strain AB-CW3 is only distantly related to other members of the genus, we propose to provisionally name it "".