15. Which of the following is not an industrial product made by the fungus Aspergillus niger?
A.Galactosidase
B.Citric acid
C.Gluconic acid
D.Lysine

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16.  The biotin level in obtaining L-gluatmic acid by fermentation using Micrococcus glutamicus is critical because
A.too low level prevents growths, hence L-glutamic acid production
B.too high level prevents L-glutamic acid production
C.both (a) and (b)
D.none of the above

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17. Most productive species among the different vitamin B12 producing Pseudomonads is
A.P. denitrificans
B.P. ovalis
C.P. aureofaciens
D.none of these

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18. The enzyme which converts optically active isomers of lactic acid to the optically inactive racemic mixture is
A.isomerase
B.racemase
C.dehydrogenase
D.invertase

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19. The sugar concentration of molasses used in fermentation should be
A.10-18%
B.20-30%
C.4-5%
D.30-38%

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20. Bacitracin, an antibiotic similar to penicillin, is produced by
A.Bacillus polymyxa
B.Streptomyces erythreus
C.Bacillus licheniformis
D.Aspergillus fumigatus

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21. Which of the following Ascomycetes are used for riboflavin production?
A.Eremnothecium ashbyii
B.Ashbya gossypii
C.Candida guilliermondia
D.Both (a) and (b)

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