Cloning a genomic region required for a high-affinity iron-uptake system in Rhizobium meliloti 1021

A collection of transposon-induced mutants of Rhizobium meliloti 1021 defective in siderophore-mediated iron assimilation were obtained and classified as biosynthetic, transport or regulatory. Several of the mutations were cloned and the adjacent sequences were used to acquire complementing DNA from the wild type. A single genomic region of about 35kb complemented all of the mutants deficient in production of the siderophore.