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Breeding of xanthan gum producing bacteria by atmospheric room temperature plasma mutagenesis
WANG Hong, WANG Lu, LYU Weifeng, SONG Wenfeng, HOU Jingjie, GOU Min, TANG Yueqin
2023, 40 (6):
39.
doi: 10.3969/j.issn.2095-1736.2023.06.039
Xanthomonas campestris
was used as the starting strain for the screening of xanthan
gum-producing strain by atmospheric room temperature plasma (ARTP)
mutagenesis. The results showed that five mutated strains were obtained
based on the diameter of colony on primary screening plate. Then, one
excellent strain X20 was found by evaluating the yield and viscosity of
xanthan gum for further secondary screening. The xanthan gum yield and
viscosity of strain X20 were 3.52 g/L and 77.30 mPa·s, which were 77.78%
and 40.03% higher than that of the starting strain, respectively.
After 10 generations of cultivation, strain X20 exhibited good genetic
stability. Different environmental factors affecting the fermentation
performance of strain X20 were studied. When glutamic acid was used as
the nitrogen source, the highest xanthan gum production and viscosity
were 7.30 g/L and 495.50 mPa·s, respectively, which were 43.27% and
22.29% higher than those of the starting bacteria. High concentration of
glutamic acid (>1 g/L) significantly suppressed the fermentation
culture viscosity of the starting strain and X20, which reduced to 21.8
mPa·s and 25.93 mPa·s at 4 g/L glutamic acid, respectively. Xanthan gum
viscosity of strain X20 was higher than that of the starting strain
under different initial pH conditions. Moreover, strain X20 was more
adapted to the fermentation environment of pH 6.5 (with viscosity of
546.5 mPa·s). With the increase of salinity, the xanthan gum yield of
strain X20 increased while its viscosity decreased, but all of them were
higher than those of the starting strain. When the salinity was 8 g/L,
the xanthan gum yield and viscosity of X20 were 12.19 g/L and 331.23
mPa·s, which were 23.05% and 109% higher than those of the starting
strain, respectively. The viscosity of X20 remained stable at different
temperatures (20 ℃-80 ℃) and high mineralization (28.90 g/L), and was
always better than that of the starting strain, showing some potential
for industrial application.
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