Development of gene transfer methods for Rubrivivax gelatinosus S1: construction, characterization and complementation of a puf operon deletion strain.

Gene transfer systems were developed in Rubrivivax (Rx.) gelatinosus S1. First, a system for conjugative transfer of mobilizable plasmids from Escherichia coli to Rx. gelatinosus S1 was established. Secondly, optimal conditions for the transformation of Rx. gelatinosus S1 by electroporation were determined. A delta puf strain was constructed. Complementation with the puf operon from a wild-type strain cloned in a replicative plasmid restored photosynthetic growth. Two insertion strains were also selected. All the strains constructed were green, due to a change in carotenoid content. Characterization of these strains provides genetic evidence for a "superoperon" organization in this bacterium.