A methyl methane sulfonate sensitive mutant of P. putida strain PpG1 is also extremely sensitive to UV-rays, compared to parent wild type cells. This mutant behaves typically as recombination less (recA) mutants of Escherichia coli and Pseudomonas aeruginosa, since as a recipient, it exhibits extremely low frequency of recombination following conjugational, transductional, and transformational gene transfer. Sex factor plasmids such as K-XYL or TOL can mobilize chromosomal genes equally well both from recA+ and recA801 donor cells, suggesting that host recombination functions are not necessary for mobilization of chromosomal genes by such plasmids.