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Abstract
Xanthomonas campestris is very important industrial microorganism for its ability to produce xanthan gum, which has multiple applications. Whey is cheep by product cultivation medium
for industrial production. Due to the low level of β-galactosidase present in X. campestris, it can not grow well and produce xanthan in whey. Therefore, suicidal plasmid pSUP5011 was mobilized from E. coli to X. campestris by transconjugation to introduce the transposon Tn5 . About 126 X. campestris transconjugants Kmr were selected and tested for its ability to produce xanthan gum in whey media.
Transconjugant no. 49 was selected as the highest xanthan producer
transconjugant. It was treated with UV-irradiation as a second step of
genetic improvement. About 45 mutants were selected and tested for
their ability to produce xanthan in whey media and some biochemical
parameters were measured. A Tn-UV-2 mutant proved to be the best xanthan producer mutants in lactose or whey media. Its xanthan gum production was characterized using Fourier transform infrared (FTIR) spectra.