1. Which of the following instrument works on the principle of batch sterilization?
a) Incubator
b) Autoclave
c) Centrifuge
d) LAF
Explanation: Autoclave is an instrument that works on the principle of batch sterilization. It is used to kill germs which invade the fermentation media. The incubator provides optimum conditions for the growth of microorganisms. Laminar Air Flow (LAF) prevents the contamination of biological samples. A centrifuge is used in the separation of liquids or gases.
2. The highest feasible temperature for batch sterilization is ________
a) 124°C
b) 120°C
c) 122°C
d) 121°C
Explanation: The highest temperature, which appears to be feasible for batch sterilization is 121°C so the procedure should be designed such that exposure of the medium to this temperature is kept to a minimum. The nutrients might get depleted if there is a long exposure.
3. The destruction of microorganisms by moist heat is described by ______________
a) Zero-order reaction
b) First-order reaction
c) Third-order reaction
d) Second-order reaction
Explanation: The destruction of microorganisms by moist heat or stream is described by First-order reaction and may be represented by the equation, -dN/dt = kN, where N is the number of viable organisms, t is the time of sterilization and reaction rate constant.
4. The contamination can be avoided by sterilizing the fermenter vessels only
a) true
b) false
Explanation: The contamination can be avoided by sterilizing the fermenter, using pure inoculum to start the fermentation, sterilizing the medium, sterilizing all the components of the fermenter, and maintaining the aseptic conditions
5. If the foreign microorganism invades the fermentation, which of the following is not likely to occur?
a) The medium will not allow the growth of contaminant
b) The contaminant may outgrow the production organism
c) The contaminant may contaminate the final product
d) The contaminant may degrade the final product
Explanation: If the foreign microorganism invades the fermenter, the medium will allow the growth of the contaminant along with the production organism. In case, it may outgrow the production organism and contaminate or degrade the final product of the fermenter.
6. Which of the following reaction occurs during the sterilization which results in browning of media?
a) Sandmeyer reaction
b) Maillard reaction
c) Cannizzaro reaction
d) Gattermann reaction
Explanation: Maillard reaction is the most common reaction which occurs during the sterilization process. It results in the browning of the medium as well as the nutrient quality is degraded. The other three- Sandmeyer, Cannizzaro, Gattermann- are the types of organic chemical reactions.
7. The long exposure of batch sterilization may lead to ____________
a) Purification of media
b) Recovery of media
c) Degradation
d) Good quality of product
Explanation: The long exposure of batch sterilization may lead to degradation of the medium. The medium may lose all its nutritional quality. The heat labile components like proteins, vitamins get degraded due to overheating.
8. Which scientists introduced the term ‘Del factor’?
a) Deindoerfer and Humphrey
b) Jacob and Monod
c) Banks and Corbett
d) Richards
Explanation: The ‘Del Factor’ was introduced by Deindoerfer and Humphrey as a design criterion for sterilization. It is also called the Nabla factor, sterilization criterion and is represented by the term ∇.
9. What is the advantage of batch sterilization over continuous sterilization?
a) Superior maintenance of medium quality
b) Ease of scale-up
c) Automatic control
d) Lower equipment costs
Explanation: The advantage of batch sterilization over continuous sterilization is that it has lower capital of equipment costs. Whereas the medium quality, automatic control, ease of scale-up are the advantages of continuous sterilization.
10. The equation for Del factor is _____________
a) ∇ = ln (N0/Nt)
b) ∇ = ln (Nt/N0)
c) ∇ = ln (N0)
d) ∇ = ln (N0Nt)
Explanation: The Del Factor is expressed as, ∇ = ln (N0/Nt), where N0 is the number of viable organisms present initially at the time of sterilization treatment and Nt is the number of viable organisms after the treatment.