Fermentation Technology Questions and Answers – Isolation and Screening of Industrially Important Microbes

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This set of Fermentation Technology Interview Questions and Answers focuses on “Isolation and Screening of Industrially Important Microbes”.

1. Which of the following is NOT a criterion for the choice of an organism?
a) The organism must be genetically stable
b) The organism must be able to produce a high yield of product
c) The optimum temperature for the growth of an organism must be above 50°C
d) The organism must be able to grow in an easily available nutrient medium
View Answer

Answer: c
Explanation: The optimum temperature for the growth of an organism should be above 40°C. This reduces the cooling costs in large scale fermenters. The microorganisms are chosen based on the rest three criteria.
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2. Full-form of ATCC is _________
a) American Type Culture Collection
b) Automatic Type Counter & Classifier
c) American Type Counter Collection
d) American Type Classifier and Collection
View Answer

Answer: a
Explanation: ATCC stands for American Type Culture Collection. It is a non-profit organization and a key resource for medical research. It is the organization which has the largest department of Research and Development.

3. Which of the following method is not used in isolation and screening of desired microorganisms?
a) Crowded plate technique
b) Auxanographic technique
c) Enrichment Culture technique
d) Hanging Drop technique
View Answer

Answer: d
Explanation: Hanging drop technique is used for motility testing of bacteria. The methods for isolation and screening are a crowded plate, auxanography, enrichment culture and use of indicator dyes.

4. The screening is isolation and detection of microorganisms of interest.
a) True
b) False
View Answer

Answer: a
Explanation: Screening is the use of highly selective procedures to allow the detection and isolation of only those microorganisms of interest from a large microbial population.

5. Which of the following method is useful for the isolation and detection of organisms having the ability to produce antibiotics?
a) Crowded plate technique
b) Auxanographic technique
c) Enrichment Culture technique
d) Indicator dye technique
View Answer

Answer: a
Explanation: The Crowded Plate Technique is used for the detection and isolation of the organisms which are antibiotic producers. The serial dilutions of soil are performed and spread on a Petri plate and allowed to grow. The well-isolated colonies are antibiotic producers with the zone of inhibition.
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6. Which of the following shows the zone of inhibition when a particular organism is grown on a Petri plate?
a) Growth Factor producers
b) Antibiotic producers
c) Organic acid producers
d) Amino acid producers
View Answer

Answer: b
Explanation: The Antibiotic producers show the zone of inhibition. It is the zone where only the growth of a particular colony is observed whereas rest all colonies get degraded by antibiotics.

7. Which of the following method is useful for isolation and detection of organisms having the ability to produce growth factors?
a) Crowded plate technique
b) Auxanographic technique
c) Enrichment Culture technique
d) Indicator dye technique
View Answer

Answer: b
Explanation: The Auxanographic technique is used for the detection and isolation of the organisms which are growth factor producers. The growth factor-like amino acids, vitamins promotes the growth of auxotrophic mutants.

8. The prototrophs are the organisms which are not capable of synthesizing all growth requirements for themselves.
a) True
b) False
View Answer

Answer: b
Explanation: The prototrophs are the organisms which are capable of synthesizing all the growth requirements by themselves whereas auxotroph is dependent on prototrophs.

9. Which of the following method is useful for isolation and detection of organisms having the ability to produce organic acids?
a) Crowded plate technique
b) Auxanographic technique
c) Enrichment Culture technique
d) Indicator dye technique
View Answer

Answer: d
Explanation: The use of Indicator Dye Technique is used for detection and isolation of the organisms which are organic acid producers. The organic acid producers produce acid which changes the colour of media and is thus detected easily.
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10. What is the pH range of Bromophenol blue?
a) 3.0 – 4.6
b) 8.0 – 10.0
c) 5 – 8
d) 6.4 – 8.0
View Answer

Answer: a
Explanation: The pH range of Bromophenol blue is 3.0 – 4.6. It changes from yellow at pH 3.0 to blue-violet at pH 4.6. It works best in this range and is also used as a tracking dye in Agarose-Gel Electrophoresis.

11. Which of the following method proceeds with 2-plate preparation?
a) Crowded plate technique
b) Auxanographic technique
c) Enrichment Culture technique
d) Indicator dye technique
View Answer

Answer: b
Explanation: Auxanographic technique proceeds with 2-plate preparation. The 1st plate is used to isolate and detect prototrophs whereas 2nd plate is used for identification of auxotrophs.

12. Which of the following dye is colourless at acidic pH and becomes red at basic pH?
a) Methyl red
b) Thymol blue
c) Phenolphthalein
d) Phenol red
View Answer

Answer: c
Explanation: Phenolphthalein has a pH range between 8.0 – 10.0. It is colourless at pH 8.0 and becomes red at pH above 10.0. It belongs to the phthalein family that is employed as an acid-base indicator.

13. Which of the following plate is used to detect and isolate organic acid producers?
a) Phenol red plate
b) Potato Dextrose Agar plate
c) MacConkey’s Agar plate
d) Rose Bengal Agar plate
View Answer

Answer: a
Explanation: Phenol Red plate is used to detect and isolate organic acid producers. The colour of plate changes from red to yellow in the zone of organisms producing organic acid.
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14. A test tube contains 9ml distilled water. 1g of soil is added to that test tube and the soil is allowed to settle down. Now, 1ml of that stock solution is taken and transferred to the 2nd test tube containing 9ml of distilled water. The process is repeated several times until the requirement is met. For this dilution, it may be said that the solution was diluted _______
a) 100-fold
b) 10-fold
c) 1000-fold
d) 2-fold
View Answer

Answer: b
Explanation: The transfer of a 1ml solution to 9ml d/w is called as serial 10-fold dilution. It is used to reduce the dense culture of cells to usable concentration.

15. Which of the following method is useful for detection and isolation of those microorganisms which are capable of growing on a particular nutrient medium?
a) Crowded plate technique
b) Auxanographic technique
c) Enrichment Culture technique
d) Indicator dye technique
View Answer

Answer: c
Explanation: The Enrichment culture technique is useful for the detection and isolation of those microorganisms which are capable of growing on a particular nutrient medium. For e.g., cellulose producers grow on nutrient medium supplied with cellulose.

Sanfoundry Global Education & Learning Series – Fermentation Technology.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn