Marine Archaeon Enhances Polyphosphate Metabolism Under Persistent Cadmium Stress.

Phosphate metabolism was studied to determine whether polyphosphate (polyP) pools play a role in the enhanced resistance against Cd and metal-removal capacity of Cd-preadapted (CdPA) . Polyphosphate kinase (PPK), exopolyphosphatase (PPX) and phosphate transporter transcript levels and their activities increased in CdPA cells compared to control (Cnt) cells. K inhibited recombinant Ma-PPK and activated Ma-PPX, whereas divalent cations activated both enzymes. Metal-binding polyP and thiol-containing molecule contents, Cd-removal, and biofilm synthesis were significantly higher in CdPA cells >Cnt cells a single addition of Cd>Cnt cells. Also, CdPA cells showed a higher number of cadmium, sulfur, and phosphorus enriched-acidocalcisomes than control cells. Biochemical and physiological phenotype exhibited by CdPA cells returned to that of Cnt cells when cultured without Cd. Furthermore, no differences in the sequenced genomes upstream and downstream of the genes involved in Cd resistance were found between CdPA and Cnt cells, suggesting phenotype loss rather than genome mutations induced by chronic Cd-exposure. Instead, a metabolic adaptation induced by Cd stress was apparent. The dynamic ability of to change its metabolism, depending on the environmental conditions, may be advantageous to remove cadmium in nature and biodigesters.