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| Table 4. | Effect of MnSO4 concentration on the production of citric acid by mutant strain of Aspergillus niger NGGCB101 in recycling fed-batch bioreactor system. |
| Sampling vs. fed-batch |
MnSO4 conc. (a x 10-5M) |
Peak day for maximal product formation |
Total acid (g/l) |
Citric acid monohydrate (g/l) |
Dry cell mass (g/l) |
Final pH |
Sugar (g/l) |
Final ferrocyanide ions conc. (ppm) |
% citric acid* |
Mycelial morphology |
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| Used |
Residual |
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| Litres |
% |
|||||||||||
| Control 1.0 |
- 11.50 |
- 1.0 x 10-6 2.0 x 10-6 3.0 x 10-6 4.0 x 10-6 |
6 2 2 2 2 |
93.34 48.44 59.52 48.98 34.31 |
88.55 43.52 56.78 47.40 30.28 |
14.55 12.05 15.50 18.00 22.50 |
2.3 3.8 3.2 3.5 3.6 |
94.5 104.0 98.7 98.9 108.5 |
55.5 46.0 52.3 51.1 41.5 |
50.58 40.90 40.05 50.50 56.44 |
89.37 41.84 57.52 49.52 31.62 |
Small pellets Large pellets Mixed mycelia Fine pellets Fine pellets |
| 2.0 |
22.50 |
1.0 x 10-6 2.0 x 10-6 3.0 x 10-6 4.0 x 10-6 |
2 2 2 2 |
46.55 68.95 60.04 57.62 |
42.34 65.55 56.78 55.02 |
11.55 14.06 16.65 19.90 |
3.8 3.1 3.3 3.4 |
96.5 102.0 105.5 112.5 |
43.5 48.0 44.5 37.5 |
34.52 36.50 42.55 49.98 |
48.23 67.59 56.90 51.21 |
Viscous Viscous Fine pellets Fine pellets |
| 3.0 |
33.50 |
1.0 x 10-6 2.0 x 10-6 3.0 x 10-6 4.0 x 10-6 |
2 2 2 2 |
74.67 86.46 80.90 78.74 |
70.98 79.86 75.54 74.24 |
10.00 12.50 15.75 18.90 |
2.6 2.4 2.5 2.5 |
98.6 99.5 100.0 108.5 |
51.4 50.5 50.0 41.5 |
30.54 32.00 38.04 39.50 |
71.98 80.26 75.54 68.42 |
Mixed mycelia Mixed mycelia Gelatinous Gummy mass |
| 4.0 |
44.50 |
0 x 10-6 2.0 x 10-6 3.0 x 10-6 4.0 x 10-6 |
2 2 2 2 |
98.66 134.5 106.6 94.32 |
92.80 128.68 98.42 90.10 |
9.50 12.30 13.50 14.45 |
2.1 1.6 1.9 2.0 |
94.6 95.0 103.5 110.0 |
45.4 55.0 46.5 40.0 |
22.45 22.80 24.55 25.00 |
83.45 96.62 89.90 86.55 |
Mixed mycelia Fluffy pellets Small pellets Small pellets |
| 5.0 |
5.50 |
1.0 x 10-6 2.0 x 10-6 3.0 x 10-6 4.0 x 10-6 |
3 3 3 3 |
79.34 95.90 92.22 89.56 |
78.25 91.20 87.52 85.40 |
8.00 9.50 10.50 12.40 |
2.4 2.2 2.5 2.6 |
120.5 115.0 104.5 100.5 |
29.5 35.0 45.5 49.5 |
20.80 21.34 24.05 24.52 |
72.42 66.78 76.98 71.05 |
Mixed mycelia Fine pellets Fine pellets Fine pellets |
| Initial
sugar concentration 150 g/l, initial pH 6.0, aeration rate 1.0l/l/min,
incubation temperature 30°C, ferrocyanide ion concentration 200 ppm.
Total volume of the fermentation medium was kept constant i.e., 9-L
(60 %) throughout for all the treatments. *On the basis of sugar used,
All the results are sum mean of three parallel replicates.
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