Genetic analysis of mannityl opine catabolism in octopine-type Agrobacterium tumefaciens strain 15955

Abstract

The genetic organization of functions responsible for mannityl opine catabolism of the Ti plasmid of Agrobacterium tumefaciens strain 15955 was investigated. A partial HindIII digest of pTi15955 was cloned into a broad host range cosmid and the clones obtained were tested for ability to confer mannityl opine degradation upon Agrobacterium. Inserts containing genes for catabolism of mannopinic acid, mannopine, agropine, and agropinic acid were obtained, spanning a segment of 43 kb on the Ti plasmid. Two clones conferring upon Agrobacterium the ability to catabolize the mannityl opines were mobilized to several Rhizobium sp., to Pseudomonas putida and P. fluorescens and to Escherichia coli. The catabolic functions were phenotypically expressed in all Rhizobium sp. tested, and in P. fluorescens, but not in P. putida or in E. coli.