Significant role of an exocellular protease in utilization of heme by Vibrio vulnificus

Clinical and environmental isolates of Vibrio vulnificus could grow in a synthetic medium supplemented with heme protein as the iron source. Protease- deficient mutants of the bacterium could not utilize any of the heme proteins in the synthetic medium, but the addition of purified V. vulnificus protease restored their growth. The protease digested all heme proteins tested and elicited heme liberation from the proteins. Furthermore, the induction of protease production by the heme proteins was demonstrated. These observations suggest that protease contributes to the efficient utilization of heme by V. vulnificus.