16. The biotin level in obtaining L-glutamic 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

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

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

19. The sugar concentration of molasses used in fermentation should be

A. 10-18%
B. 20-30%
C. 4-5%
D. 30-38%

20. Bacitracin, an antibiotic similar to penicillin, is produced by

A. Bacillus polymyxa
B. Streptomyces erythreus
C. Bacillus licheniformis
D. Aspergillus fumigatus