Fig.3-10 Total color values of C100, ΔMareA and
OE-MareA under different nitrogen sources
3.3.3 Red, orange and yellow values of monascus rice fermented by solid
state fermentation
Under the condition of rice fermentation culture without an additional
nitrogen source, the color valence of pigments from the original strain
C100 was highest at 475 nm. However, the knockout strain ΔMareA and overexpression strain OE-MareA exhibited a higher color value
at 505 nm. After adding Gln for fermentation culture, the color values
of all three strains at three wavelengths were similar to those of the
original strain, indicating that Gln addition could restore red wine
growth and reproduction to its original state unaffected by theAreA gene. Upon adding
(NH4)2SO4, there was not
much difference in color values among the three strains at three
wavelengths; however, their overall color values decreased
significantly. The most significant difference in color price among the
three strains was observed after adding NaNO3,
suggesting that NaNO3 had pronounced effects on both
knockout and overexpression strains’ color prices. When Urea was used as
a nitrogen source, changes in color price for all three strains were
similar to those obtained with NaNO3 but less effective.
In general, knocking out the MareA gene resulted in a decrease in
the color values of yellow and orange pigments, but had little effect on
red pigments; overexpression of the MareA gene led to an increase
in the color values of all three pigments. The addition of Gln restored
the growth and reproduction of red pigment to its original state, which
was unaffected by the AreA gene. When NaNO3 was
added, the utilization of NaNO3 by the strain was
regulated by the MareA gene, which prevented the strain from
using nitrogen as a nitrogen source, resulting in significantly lower
color values than the original strain. Conversely, overexpression
strains exhibited significantly higher color values than the original
strain with noticeable effects. As shown in Figure 3-11.