This set of Fermentation Technology online quiz focuses on “Commercial Applications – Surface, Submerged and Solid State Fermentation”.
1. In which of the following the microorganisms grow on the surface of the medium?
a) Submerged fermentation
b) Surface fermentation
c) Solid state fermentation
d) Batch fermentation
View Answer
Explanation: In surface fermentation, the microorganisms are allowed to grow on the surface of the liquid culture medium. It is also called as the surface culture fermentation. However, it is time-consuming and requires a large space.
2. Which of the following is not required in surface fermentation?
a) Aeration
b) Baffles
c) Agitation
d) Stirrer
View Answer
Explanation: Agitation is not provided or done in the surface culture fermentation. In this, microorganisms grow on the surface of the liquid medium without agitation. The filtrate is separate from the cell mass and is processed to recover the desired product after an appropriate incubation time.
3. Which of the following grows on the surface of the medium when Aspergillus niger is inoculated?
a) Slime layer
b) Mycelium layer
c) Foam layer
d) Capsule
View Answer
Explanation: When Aspergillus niger is allowed to grow on the surface of the liquid medium in surface culture fermentation, a layer of mycelium grows on the surface of the medium. It appears as a mycelial mat which is thick and floating over the medium.
4. In which of the following the microorganisms grow inside the medium?
a) Submerged fermentation
b) Surface fermentation
c) Solid state fermentation
d) Batch fermentation
View Answer
Explanation: In submerged fermentation, the microorganism grows inside the liquid medium. The nutrients or enzymes or reactive compounds which are required for the growth of microorganisms are added to the medium.
5. Which of the following is not true for submerged liquid fermentation?
a) The concentration of media is lower
b) Small-size bioreactors are used
c) Easy sampling
d) Expensive downstream processing
View Answer
Explanation: Usually in submerged liquid fermentation, the bioreactor used are of larger size because the concentration of media is less and is diluted. The small-sized bioreactors can be used in the solid-state fermentation. However, the sampling is easy for biomass measurement but the downstream processing is difficult and very expensive.
6. Which of the following process proceeds with having a rich fermentation broth and high oxygen concentration?
a) Submerged fermentation
b) Surface fermentation
c) Solid state fermentation
d) Batch fermentation
View Answer
Explanation: Submerged fermentation proceeds with having a rich fermentation broth and high concentration of oxygen. However, the concentration of broth is very much lower as compared to that of water content and is diluted.
7. Which of the following process occurs in the absence of free liquid?
a) Submerged fermentation
b) Batch fermentation
c) Solid state fermentation
d) Continuous fermentation
View Answer
Explanation: Solid state fermentation (SSF) occurs in the absence or near absence of free liquid. In this method, the waste products like agro-industrial wastes are utilized as a substrate which is a source of nutrients for the production of products like enzymes, etc.
8. Which of the following is not true of solid state fermentation (SSF)?
a) Easy downstream process
b) Small-size bioreactors are used
c) Greater chances of contamination
d) Less consumption of energy
View Answer
Explanation: The chances of contamination is low because of less availability of water. However, the chances of contamination are more in submerged liquid fermentation. The consumption of energy is less for gas transfer and small-size bioreactors are used. The downstream processing is cheap, easy and time-saving.
9. Which of the following bioreactor is used in group-1 SSF?
a) Rotating drum
b) Stirred-bed
c) Packed bed
d) Tray
View Answer
Explanation: Tray bioreactor is used in group-1 solid state fermentation. In group-1, the aeration is not produced naturally and is effortless. Agitation is also not required and is static. Packed bed bioreactors are used in group-2, rotating drum bioreactor is used in group-3, and stirred-bed bioreactor is used in group-4.
10. Which of the following requires a substrate as support?
a) Submerged fermentation
b) Surface fermentation
c) Solid state fermentation
d) Batch fermentation
View Answer
Explanation: Solid state fermentation (SSF) requires a substrate as solid support. The substrate should be natural and inert and must not be reactive. The substrates like bran, bagasse, and paper pulp are most commonly used.
11. Which of the following physicochemical factor does not affect SSF?
a) Pressure
b) Temperature
c) pH
d) Moisture content
View Answer
Explanation: Pressure has no role to play in the affection of SSF. Factors like temperature, pH, moisture content, gaseous environment, aeration, particle size affect the solid-state fermentation.
12. Which of the following bioreactor mix intermittently without forced aeration?
a) Packed-bed bioreactors
b) Rotating drum bioreactors
c) Spouted-bed bioreactors
d) Fluidized-bed bioreactors
View Answer
Explanation: Rotating drum bioreactors mix intermittently without forced aeration. It operates on semi-continuous or continuous mode where the rotating drum is a horizontal cylinder filled with a bed of substrate.
13. The concentration of products is low in SSF.
a) True
b) False
View Answer
Explanation: The concentration of products is high in solid state fermentation (SSF) and the rate of production is also higher and therefore, higher yield. However, the concentration of the product is low in submerged fermentation due to slower production rate and therefore, low yield.
14. SSF occurs in the presence of the liquid medium.
a) True
b) False
View Answer
Explanation: Solid state fermentation occurs in the absence of the liquid medium by employing an inert or natural substrate as solid support. The microorganisms are chosen such that it requires less water for growth such as filamentous fungi.
Sanfoundry Global Education & Learning Series – Fermentation Technology.
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