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Research has been conducted on the exotoxin A regulation in Pseudomonas aeruginosa. The role of pvdS in this regulation during chronic lung infections associated with the genetic disease cystic fibrosis has been investigated and the results are reported.

The Ti plasmid from the Agrobacterium tumefaciens biovar two strain was associated with the chromosome from a biovar one strain C58 to determine the efficiency of a Ti plasmid-encoded protein in the two bacterial strains. Analysis of vir gene induction and oncogenicity in Agrobacterium D10B/87 and C58 strains indicated the compatibility between the A6 VirA and other components of the vir gene induction response such as ChvE from the C58 chromosome. Furthermore, the deficiency in induction of strain CB100 was corrected in the presence of A6 virA.

The induction of the virulence gene vir in Agrobacterium tumefaciens was investigated using a number of A. tumefasciens strains and different solid media. Organisms grown on acidic medium solidified with bacteriological agar and supplemented with glucose expressed the virulence gene. Organisms grown on media solidified with purified agarose did not express the gene. The active principle responsible for virulence induction was extracted and purified from bacteriological agar.