GENETIC STABILITY AND XANTHAN GUM PRODUCTION IN XANTHOMONAS-CAMPESTRIS PV CAMPESTRIS NRRL B1459

A transposon (Tn5-SC) was constructed that can be used to quantify gen etic deletions or amplifications. This transposon was used to evaluate the genomic stability of Xanthomonas campestris pv. campestris NRRL B 1459 and we found that the genome of this bacterium is as stable as ot her Gram-negative bacteria or even more stable. Homologous recombinati on between plasmid sequences was determined in strain NRRL B1459 and w as found to occur at a similar level to that reported for other Gram-n egative bacteria. We report here that in X.c.c. NRRL B1459 there is no straightforward correlation between the occurrence of genetic rearran gements and frequency of homologous recombination. These data are disc ussed with respect to the reported instability of strain NRRL B1459 fo r xanthan gum production.