Biomedical Engineering Reference
In-Depth Information
Figure 2. Time course of growth and enzyme synthesis by
A. oryzae
strain FQB-01 grown in media
prepared with brewery wastewaters (BW) supplemented with different initial concentrations of soluble
starch (
2
: 0, □: 10, Ο: 20; ∆: 30;
◊
: 40 g/L).
TS
: total sugars;
TAA
: total amylolytic activity. The
cultures were carried out at 30ºC/96 h in an orbital shaker at 200 rpm.
Thus, the maximum
TAA
levels obtained in the media supplemented with 10, 20, 30 and 40 of
g of starch/L of medium were 81, 102, 113 and 116 EU/mL in BW medium and 78, 98, 107
and 111 EU/mL in MPW medium. As it can be noted, increasing the
TS
concentration from
30 to 40 g/L did not produce a significant increase in
TAA
concentrations in both MPW and
BW media (Figures 1 and 2).
From the comparison of the results obtained in both media, it can be noted that the
maximum
TAA
obtained in BW medium (116 EU/mL) was slightly higher than in MPW (111
EU/mL). In contrast, biomass concentration in MPW medium (3.47 g/L) was slightly higher
than that in BW medium (3.32 g/L). Taking into account these results, it can be concluded
that the biomass produced in BW was more productive than that in MPW, being the yields of
enzyme production (EU on g of cell dry weight) calculated as 34939.76 and 31988.47 EU/g
of cell dry weight, respectively.
During fermentation in both the starch-supplemented MPW and BW media, the pH
initially dropped from 6.0 to 4.0 after 24 h followed by its increase to 7.0 approximately (60
h), and remained constant thereafter. The
TS
concentration decreased during fermentation in
parallel with the increase in biomass and enzyme production. Final COD values of
approximately 0.16 g/L or lower were obtained in the media supplemented with 40 g of
starch/L of medium and in the media containing lower initial starch concentrations,
respectively. This indicates that at least 95% of the initial COD were removed from BW and
MPW media.
From a comparative point of view, it can be noted that the
TAA
concentrations produced
by
A. oryzae
FQB-01 were considerably higher than those produced by
Aspergillus niger
UO-
01 in both BW (70 EU/mL) and MPW (60 EU/mL) media (Salas et al., 2006).
