CONSTRUCTION OF GENOMIC BANK OF BRADYRHIZOBIUM SPP (RHIZOBIACEAE)

A wild type strain of Bradyrhizobium spp. that associates with Neonoto nia wightii (a tropical forage legume) was analysed with molecular bio logy techniques. A genomic bank of the total DNA from this bacteria wa s constructed by using the high copy number pUC 119 plasmid, as the cl oning vector, established in Escherichia coli HB101 by transformation. The total DNA of Bradyrhizobium was cloned as a collection of San 3AI fragments. Tile hybrid plasmids of tile bank contain 10-20kb, rhizobi a DNA fragments inserted into die Inc z region. Assuming that tile mol ecular weight of tile Bradyrhizobium genome is about 4,200kb, and tile average size of tile inserts is 15kb, there is more than 95% probabil ity that a nan sequence will be represented in each 10(3) transformant s, according to tile Clarke and Carbon (Cel 9: 91-99, 1976) mathematic al expression. Although various chemical and physical methods were use d, symbiotic plasmids were not detected ill this strain of rhizobia.