ICAR AICE-JRF/SRF Fermentation Technology & Dairy Biotechnology: practice questions

1 · Fermentation kinetics and scale-up · easy

A culture with a specific growth rate of 0.5 h⁻¹ has a doubling time of:

1. 2.00 h
2. 1.39 h
3. 0.69 h
4. 0.50 h

2 · Downstream processing and product recovery · medium

Ion-exchange chromatography separates proteins by:

1. Specific ligand binding
2. Size
3. Charge
4. Surface hydrophobicity

3 · Industrial production of lactic acid and other organic acids · hard

Thermophilic producers such as Heyndrickxia coagulans are attractive for lactic acid production at 50 °C because:

1. They require oxygen to convert sugar to lactic acid
2. They produce racemic acid only
3. Contamination is less likely at that temperature
4. They grow without carbon

4 · Production of enzymes: beta-galactosidase, proteases, lipases · easy

Yeast lactase from Kluyveromyces lactis is suited to milk because its pH optimum is:

1. Strongly acid, 1–2
2. Strongly alkaline, above 10
3. Near neutral, 6.5–7
4. Acidic, 3.5–5

5 · Immobilised enzymes and continuous processes · hard

The apparent Km of an immobilised enzyme is often higher than that of the free enzyme because of:

1. Loss of all active sites on the carrier
2. Higher intrinsic affinity for the substrate
3. Absence of substrate inside the beads
4. Mass-transfer limitation of substrate

6 · Immobilised enzymes and continuous processes · medium

Glutaraldehyde is used in enzyme immobilisation as a:

1. Cross-linking agent
2. Substrate
3. Gel-forming polysaccharide
4. Adsorbent resin

7 · Recombinant DNA technology and genome editing of dairy microbes · medium

Which strain-improvement method gives products not regulated as GMOs?

1. Selection of spontaneous phage-resistant mutants
2. CRISPR insertion of a foreign gene into the chromosome
3. Plasmid with an E. coli gene
4. Transgenic expression of chymosin

8 · Precision fermentation of milk proteins · easy

Precision fermentation differs from biomass fermentation in that:

1. The cells themselves are the product
2. It is a traditional, spontaneous food fermentation process
3. No microorganism is used
4. The target is a protein purified from the culture

9 · Precision fermentation of milk proteins · medium

2'-Fucosyllactose for infant formula is produced commercially by:

1. Solid-state fermentation
2. Precision fermentation in engineered E. coli
3. Chemical synthesis from lactose alone, without enzymes
4. Extraction from human milk

10 · Precision fermentation of milk proteins · medium

Which yeast, formerly called Pichia pastoris, is a host for precision fermentation?

1. Debaryomyces hansenii
2. Saccharomyces boulardii
3. Kluyveromyces marxianus
4. Komagataella phaffii