Molecular Mechanism of Iron Transport Systems in Vibrio

The ability to acquire iron from the environment is often an important virulence factor for pathogenic bacteria and Vibrios are no exception to this. Vibrios are reported mainly from marine habitats and most of the species are pathogenic. Among those, the pathogenic vibrios eg. V cholerae, V. parahaemolyticus, V. vulnificus causes foodborne illnesses. Vibrios are capable of producing all different classes of siderophores like hydroxamate (aerobactin), catecholate (vibriobactin, fluvibactin), carboxylate (vibrioferrin), and amphiphilic (amphibactin). Every different species of vibrios are capable of utilizing some endogenous or xenosiderophores. Being Gram-negative bacteria, Vibrios import iron siderophore via TonB dependent transport system and unlike other Gamma proteobacteria these usually possess two or even three partially redundant TonB systems for iron siderophore transport. Other than selected few iron siderophores, most pathogenic Vibrios are known to be able to utilize heme as the sole iron source, while some species are capable of importing free iron from the environment. As per the present knowledge, the spectrum of iron compound transport and utilization in Vibrios is better understood than the siderophore biosynthetic capability of individual species.