Plasmid pNZ521, containing phospho-beta-galactosidase, maturation protein and proteinase P genes was conjugally transferred for the first time from L.lactis into X.campestris XLM1.After 30 generations 67% of the tested colonies were resistant to chloramphenicol in the transconjugant proteinase activity appeared in the growth medium, whereas in L.lactis MG1820 it was extracted from the cell walt Proteinase activity and production of xanthan gum were studied in different concentrations of whey. Xanthan gum production was found much higher in all cultures with the transconjugant strain XLM1521.