Fermentation technology for plant metabolites: ergot alkaloids, SCP, enzymes MCQs With Answer

Introduction

This quiz set focuses on fermentation technology for production of plant-related metabolites—specifically ergot alkaloids, single-cell protein (SCP), and industrial enzymes—tailored for M.Pharm students studying Medicinal Plant Biotechnology (MPG 201T). Questions cover microbial producers, biosynthetic pathways, upstream and downstream process parameters, reactor strategies (submerged vs. solid-state), scale-up considerations, strain improvement, quality control, analytical methods and regulatory/safety aspects. Emphasis is placed on practical fermentation variables (pH, aeration, C:N ratio, kLa), bioprocess optimization, and purification approaches relevant to pharmaceutical-grade products. This set will test conceptual understanding and applied problem-solving needed for designing and evaluating fermentation processes for plant metabolite production.

Q1. Which organism is the classical producer of ergot alkaloids used in pharmaceutical production?

• Claviceps purpurea
• Aspergillus niger
• Saccharomyces cerevisiae
• Penicillium chrysogenum

Correct Answer: Claviceps purpurea

Q2. The first committed enzymatic step in ergot alkaloid biosynthesis is the prenylation of tryptophan to form which intermediate?

• Dimethylallyltryptophan (DMAT)
• Lysergic acid
• Ergoline
• Ergotamine

Correct Answer: Dimethylallyltryptophan (DMAT)

Q3. Which fermentation mode is generally preferred for large-scale production of fungal ergot alkaloids to maintain sterility and control parameters?

• Submerged (liquid) fermentation in stirred tank reactors
• Open-air solid-state farming on fields
• Non-sterile batch lagoons
• Continuous flow packed-bed photobioreactors

Correct Answer: Submerged (liquid) fermentation in stirred tank reactors

Q4. In producing single-cell protein (SCP) from yeast, which downstream treatment is often necessary to make it suitable for food/feed due to high nucleic acid content?

• RNA reduction by heat and enzymatic treatments
• Lyophilization without pretreatment
• Centrifugation only
• Direct spray-drying with no processing

Correct Answer: RNA reduction by heat and enzymatic treatments

Q5. Which parameter most directly influences oxygen transfer rate and is critical for aerobic enzyme production in stirred tank reactors?

• Volumetric mass transfer coefficient (kLa)
• Thermal conductivity of broth
• Viscosity of the antifoam agent
• Conductivity of the medium

Correct Answer: Volumetric mass transfer coefficient (kLa)

Q6. Solid-state fermentation (SSF) often provides advantages for production of certain enzymes. Which of the following is a primary advantage of SSF over submerged fermentation?

• Higher product concentration with lower water activity that can favor certain fungal enzymes
• Complete elimination of contamination risk
• Easier scale-up to large stirred tanks without modifications
• Better control of dissolved oxygen in liquid phase

Correct Answer: Higher product concentration with lower water activity that can favor certain fungal enzymes

Q7. Which class of ergot alkaloids includes peptide-containing compounds such as ergotamine and ergocristine?

• Ergopeptines
• Ergoline alcohols
• Lysergic acids
• Indole monoterpenoids

Correct Answer: Ergopeptines

Q8. For improving ergot alkaloid yields by strain development, which strategy directly modifies biosynthetic genes to increase precursor flux?

• Metabolic engineering of eas (ergot alkaloid synthesis) pathway genes
• Random UV mutagenesis without screening
• Repeated subculturing on agar plates
• Supplementing medium with generic vitamins only

Correct Answer: Metabolic engineering of eas (ergot alkaloid synthesis) pathway genes

Q9. Which analytical technique is most commonly used for quantitative determination and purity assessment of ergot alkaloids in fermentation broth?

• High-performance liquid chromatography (HPLC) with UV or MS detection
• Simple colorimetric pH indicator strips
• Paper chromatography with iodine staining
• Visible spectrophotometry at 700 nm

Correct Answer: High-performance liquid chromatography (HPLC) with UV or MS detection

Q10. When designing a fed-batch process to maximize enzyme production, which feeding strategy helps avoid catabolite repression and maintain enzyme induction?

• Controlled low-rate substrate feed maintaining sub-saturating carbon levels
• Single large substrate spike at inoculation
• Continuous high-rate glucose feed leading to overflow metabolism
• No feed; static batch culture to stationary phase

Correct Answer: Controlled low-rate substrate feed maintaining sub-saturating carbon levels

Q11. Which unit operation is most appropriate for concentrating extracellular enzymes from a fermentation broth prior to chromatography?

• Ultrafiltration using appropriate molecular weight cut-off membranes
• Simple filtration through cotton wool
• Settling by gravity alone
• Direct injection into HPLC without concentration

Correct Answer: Ultrafiltration using appropriate molecular weight cut-off membranes

Q12. In SCP production from methanol-utilizing yeasts (e.g., Pichia), what is a critical industrial concern that must be managed?

• Toxicity and volatility of methanol feed and formation of formaldehyde
• Excessive oxygen solubility causing hyperoxia in cells
• Formation of ergot alkaloids as major byproducts
• Instability of yeast cell walls in water

Correct Answer: Toxicity and volatility of methanol feed and formation of formaldehyde

Q13. Which physiological factor is commonly manipulated to favor secondary metabolite (ergot alkaloid) production over biomass growth?

• Limiting a key nutrient (e.g., nitrogen) while maintaining carbon source
• Maximizing temperature to increase growth rate
• Providing excess readily metabolizable sugars
• Maintaining high dissolved oxygen at all times

Correct Answer: Limiting a key nutrient (e.g., nitrogen) while maintaining carbon source

Q14. Immobilization of microbial cells for enzyme production can provide which major benefit?

• Enhanced operational stability and easier reuse of biocatalyst
• Increased rates of genetic mutation
• Complete elimination of mass transfer limitations
• Guaranteed increase in specific growth rate

Correct Answer: Enhanced operational stability and easier reuse of biocatalyst

Q15. Which pre-treatment is commonly used to extract lysergic acid or ergopeptines from Claviceps sclerotia for purification?

• Alkaline or acidic extraction followed by organic solvent partitioning
• Direct aqueous filtration with no pH adjustment
• Steam distillation at low pressure
• Ultraviolet irradiation to volatilize compounds

Correct Answer: Alkaline or acidic extraction followed by organic solvent partitioning

Q16. During industrial enzyme fermentation, protease contamination that degrades product enzymes can be minimized by which approach?

• Using protease-deficient host strains or adding specific protease inhibitors during downstream processing
• Raising the temperature to denature all proteins indiscriminately
• Adding extra carbon source to stimulate protease production
• Prolonged stationary phase cultivation to exhaust proteases

Correct Answer: Using protease-deficient host strains or adding specific protease inhibitors during downstream processing

Q17. What is a principal regulatory concern for production of ergot alkaloids used in medicines?

• Strict control of impurity profile and ergot alkaloid analog composition due to potency and toxicity
• Requirement to produce ergot only by non-microbial chemical synthesis
• No regulatory oversight because ergot is a natural product
• Mandatory inclusion of SCP as a contaminant

Correct Answer: Strict control of impurity profile and ergot alkaloid analog composition due to potency and toxicity

Q18. Which microbial group is most commonly exploited for high-yield single-cell protein production due to rapid growth and high protein content?

• Yeasts (e.g., Saccharomyces, Candida, Pichia)
• Clostridia spore-formers
• Filamentous algae only
• Obligate intracellular bacteria

Correct Answer: Yeasts (e.g., Saccharomyces, Candida, Pichia)

Q19. In scale-up from lab to pilot fermenter for enzyme production, which dimensionless number is often preserved to maintain similar mixing and oxygen transfer characteristics?

• Reynolds number or power input per unit volume (P/V) to keep hydrodynamics comparable
• Absolute agitation speed (rpm) regardless of vessel size
• Time of day the culture is inoculated
• Volume of seed culture only

Correct Answer: Reynolds number or power input per unit volume (P/V) to keep hydrodynamics comparable

Q20. Which downstream analytical method is essential to confirm the identity and determine the molecular mass of novel ergot alkaloid congeners?

• Liquid chromatography–mass spectrometry (LC–MS/MS)
• Simple titration with NaOH
• Thermogravimetric analysis (TGA)
• Paper electrophoresis without standards

Correct Answer: Liquid chromatography–mass spectrometry (LC–MS/MS)

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