Production of single-cell protein MCQs With Answer

Production of single-cell protein MCQs With Answer

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Production of single-cell protein (SCP) MCQs With Answer is designed for M.Pharm students aiming to master the biotechnological production, processing, and safety aspects of microbial protein as an alternative protein source. This set of MCQs focuses on microbial strains, substrates, fermentation modes, downstream separation, nutritional quality, anti-nutritional factors, regulatory considerations, and scale-up challenges. Questions emphasize critical parameters such as oxygen transfer, nucleic acid reduction, analytical methods for protein estimation, and industrial processing techniques. The quiz balances conceptual depth and practical application to prepare postgraduate pharmaceutical biotechnology students for exams and research in SCP production and evaluation.

Q1. Which organism is classically used in industrial production of single-cell protein known as “torula yeast”?

  • Saccharomyces cerevisiae
  • Candida utilis
  • Fusarium venenatum
  • Methylococcus capsulatus

Correct Answer: Candida utilis

Q2. A major nutritional concern with high SCP intake is elevated levels of which compound that must be reduced to make SCP suitable for human consumption?

  • Chitin
  • Nucleic acids (RNA/DNA)
  • Cellulose
  • Phytic acid

Correct Answer: Nucleic acids (RNA/DNA)

Q3. Which method is commonly applied to lower nucleic acid content in microbial biomass to acceptable levels?

  • Spray drying at low temperatures
  • Enzymatic hydrolysis with nucleases
  • Ion-exchange chromatography
  • Lyophilization without pretreatment

Correct Answer: Enzymatic hydrolysis with nucleases

Q4. Which substrate class is associated with methylotrophic bacteria used for SCP production from C1 compounds?

  • Plant-derived lignocellulosic hydrolysates
  • Molasses and starch hydrolysates
  • Methane and methanol
  • Crude glycerol only

Correct Answer: Methane and methanol

Q5. In large-scale SCP fermentation where oxygen transfer is limiting, the key parameter to monitor and optimize is:

  • kLa (volumetric oxygen transfer coefficient)
  • Redox potential only
  • Foam collapse time
  • Supersaturation pressure

Correct Answer: kLa (volumetric oxygen transfer coefficient)

Q6. Which downstream technique is most effective for concentrating microbial biomass from a dilute fermentation broth?

  • Spray drying
  • Centrifugation and decantation
  • Gel-permeation chromatography
  • Dialysis

Correct Answer: Centrifugation and decantation

Q7. Fusarium venenatum is commercially exploited for production of which type of SCP-related product?

  • Single-cell oil for biodiesel
  • Quorn mycoprotein (fungal mycoprotein for food)
  • Yeast extract supplements
  • Algal biomass for spirulina

Correct Answer: Quorn mycoprotein (fungal mycoprotein for food)

Q8. Which analytical method provides the most direct estimate of total protein content in SCP biomass?

  • Kjeldahl nitrogen determination with protein conversion factor
  • UV-Vis absorbance at 280 nm
  • Dry cell weight measurement
  • Optical density at 600 nm (OD600)

Correct Answer: Kjeldahl nitrogen determination with protein conversion factor

Q9. A major advantage of using agro-industrial wastes (e.g., molasses, whey) as SCP feedstock is:

  • Complete elimination of downstream processing
  • Zero risk of contamination
  • Cost reduction and valorization of waste streams
  • Guaranteed superior amino acid profile

Correct Answer: Cost reduction and valorization of waste streams

Q10. Which microbial feature increases the digestibility and bioavailability of SCP for monogastric animals?

  • High chitin content in cell walls
  • Rigid cellulose layers
  • Cell wall susceptibility to enzymatic or mechanical disruption
  • Presence of mycotoxins

Correct Answer: Cell wall susceptibility to enzymatic or mechanical disruption

Q11. In continuous culture of SCP, maintaining the dilution rate above the maximum specific growth rate (D > µmax) will result in:

  • Stable high biomass concentration
  • Washout of the culture
  • Maximal product yield per cell
  • Spontaneous mutation to slower-growing strains

Correct Answer: Washout of the culture

Q12. Which of the following is a regulatory concern specifically for bacterial SCP when used in food applications?

  • Allergenicity from fungal proteins
  • Endotoxin (lipopolysaccharide) contamination
  • Vitamin overdosage
  • High water activity in dried product

Correct Answer: Endotoxin (lipopolysaccharide) contamination

Q13. Spray drying of SCP biomass is preferred industrially mainly because it:

  • Preserves nucleic acids without modification
  • Provides rapid moisture removal and yields stable powder
  • Always increases lysine content
  • Is the lowest energy drying method

Correct Answer: Provides rapid moisture removal and yields stable powder

Q14. Genetic or metabolic engineering of SCP strains is commonly used to:

  • Increase nucleic acid content for better flavor
  • Reduce essential amino acids to improve palatability
  • Enhance essential amino acid profile and reduce unwanted metabolites
  • Convert protein into lipids solely

Correct Answer: Enhance essential amino acid profile and reduce unwanted metabolites

Q15. Which flocculant type is often used to improve biomass settling and reduce centrifugation energy in SCP harvest?

  • Anionic surfactants like SDS
  • Polyelectrolyte cationic flocculants (e.g., chitosan or polyDADMAC)
  • Strong oxidizing agents like hypochlorite
  • Non-ionic detergents

Correct Answer: Polyelectrolyte cationic flocculants (e.g., chitosan or polyDADMAC)

Q16. When using lignocellulosic hydrolysates as substrate for SCP, a major pretreatment challenge is:

  • Excessive simple sugar concentration causing no effect
  • Generation of inhibitory compounds (furans, phenolics) during hydrolysis
  • Complete sterilization is unnecessary
  • Too high protein content in hydrolysate

Correct Answer: Generation of inhibitory compounds (furans, phenolics) during hydrolysis

Q17. Which method provides direct information about amino acid composition of SCP and is important for nutritional assessment?

  • Gas chromatography of intact cells
  • Amino acid analysis after acid hydrolysis (HPLC/UPLC)
  • FTIR spectroscopy of dried biomass
  • Optical density calibration curve

Correct Answer: Amino acid analysis after acid hydrolysis (HPLC/UPLC)

Q18. In the context of SCP production from methane-oxidizing bacteria, a major industrial challenge is:

  • Low methane availability worldwide
  • Safety and handling of flammable gaseous substrate and gas–liquid mass transfer
  • Inability of bacteria to assimilate carbon
  • Excessive nitrogen fixation causing imbalance

Correct Answer: Safety and handling of flammable gaseous substrate and gas–liquid mass transfer

Q19. Which statement correctly describes the difference between heterotrophic and autotrophic SCP production?

  • Heterotrophic uses inorganic carbon; autotrophic uses organic substrates
  • Heterotrophic organisms require organic carbon sources; autotrophic organisms fix CO2 or utilize C1 compounds
  • Autotrophic systems never need oxygen
  • Heterotrophic processes always produce lower protein content

Correct Answer: Heterotrophic organisms require organic carbon sources; autotrophic organisms fix CO2 or utilize C1 compounds

Q20. Which safety testing is essential for SCP destined for human food to ensure absence of harmful metabolites?

  • Determination of microbial nucleic acid by Dumas method alone
  • Screening for mycotoxins, bacterial endotoxins, and residual toxins by validated analytical assays
  • Only sensory evaluation for off-odors
  • Measurement of total ash as the single criterion

Correct Answer: Screening for mycotoxins, bacterial endotoxins, and residual toxins by validated analytical assays

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