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Table 1. Screening
of stock cultures for citric acid production. All
the fermentations were carried out at 30ºC following growth on 150 g/l
initial sugar concentration. The initial pH of the molasses medium was
kept constant at 6.0 throughout the fermentation period of 6-days.
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Stock cultures of Aspergillus niger |
Dry cell mass (g/l) |
Sugar consumed (g/l) |
Citric acid monohydrate (g/l) |
% Yield* |
Mycelial morphology |
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GCBT1 |
16.53 |
94.65 |
42.56 |
44.96 |
Small shiny pellets |
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GCBT2 |
14.95 |
102.40 |
78.18 |
76.35 |
Intermediate pellets |
|
GCBT3 |
18.24 |
78.04 |
15.25 |
19.54 |
Gelatinous mass |
|
GCBT4 |
16.25 |
81.52 |
6.62 |
8.12 |
Viscous |
|
GCBT5 |
23.72 |
67.82 |
27.69 |
40.83 |
Dumpy mass |
|
GCBT6 |
14.75 |
87.64 |
11.04 |
12.60 |
Viscous |
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GCBT7 |
20.05 |
91.45 |
84.95 |
92.89 |
Intermediate pellets |
|
GCBT8 |
19.12 |
97.60 |
72.98 |
74.77 |
Mixed pellets |
|
GCBT9 |
20.14 |
90.00 |
18.86 |
20.96 |
Gummy mass |
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GCBT10 |
22.68 |
105.28 |
58.14 |
55.22 |
Small round pellets |
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GCBT11 |
18.04 |
99.06 |
41.02 |
41.41 |
Fluffy mass |
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GCBT12 |
19.55 |
89.95 |
13.34 |
14.83 |
Viscous |
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* based on the sugar consumed. Molasses was obtained from Madina Sugar Mills. |
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