Biology

Microorganisms in Food Production

1,086 Questions

Microorganisms play a vital role in food production through processes like fermentation and bioprocessing. Questions on this topic cover the use of yeast, bacteria, and industrial microbiology. These concepts are important for science sections in various competitive exams.

Alcoholic fermentationDairy beverage productionIndustrial ethanol preparationCitric acid productionBiodigester temperature

Microorganisms in Food Production Questions

Multiple choice

During downstream process of penicillin fermentation, phosphoric acid or sulphuric acid is added to the medium to _________.

  1. kill all fungi

  2. lower the pH and convert penicillin to anionic form

  3. produce phosphate or sulphate salt of penicillin

  4. precipitate penicillin
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lower the pH and convert penicillin to anionic form: the acids lower the pH to 2 or 2.5. This helps to convert penicillin to anionic form and the broth is immediately extracted in a Podbielniak counter current solvent extractor.

Multiple choice

A scientist produced an enzyme by microbial fermentation. He wanted to test it and thus, disintegrated it into its constituent parts: apoenzyme and cofactor. Each of the parts is heated for 3 minutes at 100°C. Subsequently, various combinations are tested for their ability to perform the enzymatic function. Which of the following combinations will retain its functionality?

  1. Unheated apoenzyme and unheated cofactor.

  2. Heated apoenzyme and unheated cofactor.

  3. Heated apoenzyme and heated cofactor.

  4. More than one of the above combinations is possible.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Unheated apoenzyme and unheated cofactor. An enzyme is made up of two parts- apoenzyme, that is the protein part and a cofactor that is the non protein part. Since apoenzyme is protein in nature, if it is heated at a high temperature, it will get denatured. But since cofactor is non protein in nature, it remains unaltered even at high temperature.

Multiple choice

During fermentation, continuous feed is used to maintain __________.

  1. temperature

  2. cell number

  3. substrate concentration

  4. product concentration
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Substrate concentration: During fermentation, microorganisms utilize substrate to produce products. But as fermentation proceeds the substrate concentration decreases, which is replenished by continuous feed of substrate.

Multiple choice

Torulopris utilis is a microorganism used _________.

  1. for production of third generation antibiotics

  2. for synthesis of citric acid

  3. as a flavouring yeast

  4. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As a flavoring yeast: Torulopris utilis is a yeast, which is produced from wood sugar, pasteurized and in activated, dried and formed into a powder to produce a light green coloured yeast that has meaty taste.

Multiple choice

Aeration and agitation is an important parameter in fermentation technology. In a stirring vessel, the power consumption by an agitator can be evaluated by __________.

  1. strain gauge attached to the shaft of agitator

  2. meter attached to the agitator motor

  3. dynamometer

  4. all of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During agitation, the force built and power consumed by the agitator is not equal all over the fermentor. Therefore, it needs to be assessed at every point, which are done by the above 3 procedures.

Multiple choice

During wine production, if aeration is done, which of the following organisms is likely to grow?

  1. Acetobacter

  2. Lactobacillus

  3. Yeast

  4. Penicillium
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Acetobacter: Wine is produced by alcoholic fermentation of juice from ripe grapes. This is anaerobic fermentation facilitated by yeasts Saccharomyces present in the grape. But Acetobacter is an aerobic organism that is naturally present in grapes, which grows if aeration is done.

Multiple choice

A researcher inoculated a bottle of fruit juice with yeast and left it open for few days. He observed that first C2H5OH + CO2 are produced and next CO2 + H2O are produced. Which of the following is correct inference of the process?

  1. The yeast uses alcohol for C and energy.

  2. The yeast utilizes glycolysis and then changes to fermentation.

  3. The yeast utilizes fermentation and then changes to respiration.

  4. None of the above is correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The yeast utilizes fermentation and then changes to respiration. Since, C2H5OH + CO2 are produced first, it means fermentation is the first process. Next, CO2 + H2O production indicates respiration.

Multiple choice

Generation of foam is a serious problem during fermentation. Presence of which type of bacteria is likely to cause foam in a batch fed fermentation?

  1. Proteolytic bacteria<o:p></o:p>

  2. Lignin degrading bacteria<o:p></o:p>

  3. Fat degrading bacteria<o:p></o:p>

  4. Cellulolytic bacteria<o:p></o:p>

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Proteolytic bacteria: these perform protein fermentation and medium containing high levels of protein and peptides, during fermentation yield to foams which are very stable. Therefore, antifoaming agents need to be added in the fermentor.    

Multiple choice

While making CO2 transfer from the bulk liquid to an air bubble inside a fermentor, which of the following step has the maximum resistance?

  1. While moving across the cell membrane of microorganisms<o:p></o:p><o:p></o:p>

  2. While moving through the bubble boundary layer<o:p></o:p>

  3. While moving through bulk fermentation medium<o:p></o:p>

  4. While moving through the liquid gas interface<o:p></o:p>

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

While moving through bulk fermentation medium: CO2 is a large molecule as compared to O2. Due to its large structure, it faces a high resistance at every step while travelling from its source to the microorganism. The maximum resistance is offered while it is travelling through the bulk liquid fermentation medium due to the presence of large number of ingredients which makes the medium viscous.  

Multiple choice

A flask containing 100 ml and a bioreactor containing 1 liter of nutrient, both were inoculated with 500 cells of a certain bacteria sp. The flask was incubated on mechanical shaker and aeration was introduced in bioreactor at 37°C for 2 hrs. The final pH in flask was found to be 5 with 105 cells/ml and that in bioreactor was 7 with 1012 cell/ml.

Which of the following is most apparent from the above statement?

  1. Bioreactors are better vessels for maintaining bacterial growth for a longer time.

  2. Bacteria does not like flasks.

  3. Flasks are better for acid production by fermentation.

  4. Flasks are bactericidal.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bioreactors are better vessels for maintaining bacterial growth for a longer time: The conditions in both the vessels are same. But bacterial concentration is more in bioreactor because they get large space to multiply and divide.

Multiple choice

Match the following organisms with their products produced by fermentation commercially

 
Column I Column II
A. Clostridium 1. Acetone-Butanol
B. Bacillus licheniformis 2. Amylase
C. Bacillus subtilis 3. Bacitracin
D. Propinobacterium 4. Vitamin B12

  1. A - 1, B - 2, C - 3, D - 4

  2. A - 1, B - 3, C - 2, D - 4

  3. A - 4, B - 3, C - 1, D - 2

  4. A - 2, B - 1, C - 4, D - 3
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A - 1, B - 3, C - 2, D - 4: Clostridium acetobutylicum is the organism used in Acetone-Butanol fermentation, Bacillus licheniformis is used in Amylase production, Bacillus subtilis is exploited to manufacture Bacitracin antibiotic. Previously, Saccharomyces sp was used to produce Vitamin B12 but now a days, Propinobacterium sp is used because yield is more.

Multiple choice

Which of the following microorganisms is/are used in the making of chocolate?

A. Kloeckera africana B. Kocuria rhizophila C. Gluconacetobacter oboediens D. Kluyveromyces marxianus

  1. Only A

  2. Only B

  3. Only B and C

  4. Only A and C

  5. Only A and D
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The fungi, Kloeckera africana and Kluyveromyces marxianus both are used in the making of chocolate. The bacteria Kocuria rhizophila is used in the making of cheese and the bacteria Gluconacetobacter oboediens is used in the making of vinegar.