Understanding Fermentation: Process and Steps

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Questions and Answers

In the context of fermentation, what is zymology?

The disposal of effluents produced by the process.
The science of fermentation. (correct)
The process of converting sugar to acids, gases, or alcohol.
The bulk growth of microorganisms on a growth medium.

Which of the following is NOT a primary purpose of fermentation processes?

Creating recombinant products.
Synthesizing inorganic compounds. (correct)
Producing microbial enzymes.
Modifying a compound via transformation.

During fermentation, why is the sterilization of the medium, fermenters, and ancillary equipment crucial?

To ensure that the equipment can be operated aseptically. (correct)
To provide adequate aeration and agitation.
To reduce power consumption during the fermentation process.
To promote the growth of the organism in the production fermenter.

What is the MOST important factor to consider when designing a fermenter for long-term operation?

The vessel should be capable of being operated aseptically for a number of days. (D) Signup and view all the answers

Why is it important to minimize power consumption in a fermenter?

To reduce operational costs. (B) Signup and view all the answers

What design consideration helps reduce the labor required for fermenter operation, harvesting, cleaning, and maintenance?

Designing the vessel for minimal manual intervention. (B) Signup and view all the answers

Why should the geometry of a production fermenter be similar to that of smaller, pilot-scale vessels?

To enable easier and more reliable scale-up of the fermentation process. (A) Signup and view all the answers

What is the MOST important reason for using the cheapest suitable materials in the construction of a fermenter?

To reduce initial capital expenditure. (B) Signup and view all the answers

In the context of fermenter vessel design, which type of seal is exclusively suitable for creating a reliable aseptic connection between metal to metal joints?

O-ring seal (A) Signup and view all the answers

What is the primary function of agitation in submerged microbial cultures within a fermenter?

To ensure a uniform suspension of microbial cells and a homogenous nutrient medium. (C) Signup and view all the answers

Which of the following agitator types is characterized by a disc with a series of rectangular vanes set vertically around its circumference?

Disc turbine agitator (B) Signup and view all the answers

In a vaned disc agitator, where are the rectangular vanes attached?

Vertically to the underside of the disc. (D) Signup and view all the answers

What role does the skirt-like shield play in a simple stirrer seal design, particularly concerning the lower bearing and housing?

Preventing airborne contaminants from settling on the bearing. (C) Signup and view all the answers

What is the primary factor to consider when selecting materials for constructing a fermenter that requires strict aseptic conditions?

The material's ability to withstand repeated steam sterilization cycles. (B) Signup and view all the answers

What is the purpose of the springs or expanding bellows that press the components together in a mechanical seal for a stirrer shaft?

To ensure continuous contact between the rotating and stationary parts of the seal. (A) Signup and view all the answers

According to the American Iron and Steel Institute (AISI), what is the key differentiating factor between steel alloys and stainless steels?

The percentage of chromium content. (B) Signup and view all the answers

Why is oxygen transfer so important in fermentation processes?

Most industrial fermentation processes are aerobic and require oxygen for product formation and cell growth. (B) Signup and view all the answers

When selecting a material for seals in fermentation equipment, why are nitrile or butyl rubbers typically preferred?

They can withstand the fermentation process conditions. (A) Signup and view all the answers

What property is crucial for materials used in fermenter construction to prevent contamination?

Resistance to corrosion. (C) Signup and view all the answers

Which of the following best describes the role of chromium in enhancing the corrosion resistance of stainless steel?

It creates a thin, hydrous oxide film that is self-healing and insoluble. (D) Signup and view all the answers

For a fermentation process using a Hazard Group 1 organism on a large scale, what level of containment is typically required?

Good Industrial Large Scale Practice (GILSP). (B) Signup and view all the answers

In the context of fermenter design, why is glass a useful material for small-scale fermenters (1 to 30 dm3)?

It provides smooth, non-toxic, corrosion-proof surfaces and allows easy visual inspection. (C) Signup and view all the answers

How does the inclusion of molybdenum in stainless steel enhance its properties in fermenter construction?

It improves resistance to solutions of halogen salts and pitting by chloride ions. (A) Signup and view all the answers

What minimum percentage of chromium is generally required in steel to develop an effective corrosion-resistant film?

10 to 13% (A) Signup and view all the answers

What is the primary function of baffles in agitated vessels?

To prevent vortex formation and improve aeration efficiency. (C) Signup and view all the answers

Why is it recommended to have a gap between the baffles and the vessel wall in a fermenter?

To promote a scouring action that minimizes microbial growth. (A) Signup and view all the answers

Which of the following describes a nozzle sparger?

A single, open, or partially closed pipe. (C) Signup and view all the answers

What is a major disadvantage of using porous spargers in fermentation processes?

The fine holes can easily become blocked by microbial growth. (D) Signup and view all the answers

What is the recommended minimum diameter for sparger holes in an orifice sparger and why?

6 mm, to minimize pressure drop and prevent blockage. (A) Signup and view all the answers

In what configuration are perforated pipes typically arranged in small stirred fermenters using orifice spargers?

Below the impeller in the form of crosses or rings. (B) Signup and view all the answers

What is the primary reason that heating is not generally used for sterilization of air in large-scale fermentation processes?

Heating is too costly for large-scale operation. (D) Signup and view all the answers

Considering the design of a nozzle sparger, what is the rationale for positioning it as far away as possible from the impeller?

To prevent the impeller from becoming flooded by the air stream. (D) Signup and view all the answers

What is the primary driving force for the circulation of medium in an air-lift fermenter?

The density difference between the liquid column in the riser and the downcomer. (B) Signup and view all the answers

Why might an air-lift fermenter be preferred over a mechanically stirred fermenter for producing single-cell protein (SCP) from methanol?

Mechanically stirred fermenters require external cooling loops due to high aeration and agitation rates, making them uneconomical. (C) Signup and view all the answers

In the context of microbial culture oxygen supply, what does an 'oxygen satisfaction' value below unity imply?

The dissolved oxygen concentration is below the critical level. (B) Signup and view all the answers

According to Bartholomew et al. (1950), which of the following is NOT a step in the transfer of oxygen from air to a microbial cell during fermentation?

The active transport of oxygen across the cell membrane. (D) Signup and view all the answers

What is the significance of the 'critical dissolved oxygen concentration' for a microorganism like Brevibacterium flavum?

It's the minimum oxygen concentration required for optimal biosynthesis of certain metabolites. (D) Signup and view all the answers

What is the approximate circulation time in air-lift fermenter loops of 45-m height, as mentioned in the text?

120 seconds (D) Signup and view all the answers

In an air-lift fermenter, what would be the likely effect of increasing the air flow rate into the riser tube, assuming other conditions remain constant?

It would increase the circulation rate of the medium due to a greater density difference between the riser and downcomer. (C) Signup and view all the answers

How would you describe the relationship between aeration/agitation and oxygen demand in an industrial fermentation process?

Aeration and agitation must be adjusted to satisfy the oxygen demand of the microbial culture. (D) Signup and view all the answers

What is the primary function of steam traps in steam lines within a fermentation process?

To automatically collect and remove condensate from the steam lines. (A) Signup and view all the answers

Which type of valve is best suited for aseptic operations and can handle mycelial broths in a fermenter?

Ball Valve (B) Signup and view all the answers

Why are gate valves unsuitable for regulating flow in a fermenter system?

They are designed for fully open or fully closed positions, not for partial flow. (B) Signup and view all the answers

What is a critical maintenance requirement for gate valves due to their design?

Checking and tightening the nut around the stem to prevent leakage. (A) Signup and view all the answers

In a steam trap, what is the function of the device that opens or closes the valve?

To measure a parameter of the condensate and determine if it should be discharged. (C) Signup and view all the answers

How does a needle valve achieve accurate control of steam or liquid flow?

By utilizing a tapered plug or needle fitting into a tapered valve seat to create a variable orifice. (D) Signup and view all the answers

Why are needle valves considered to have very limited applications in aseptic processes?

Their complex design makes them difficult to clean and sterilize effectively. (D) Signup and view all the answers

Which of the following describes the primary mechanism by which a ball valve prevents deposition of matter and maintains aseptic conditions?

The ball is sealed between two wiping surfaces that clean the surface during operation. (C) Signup and view all the answers

Flashcards

Fermentation

A metabolic process converting sugar to acids, gases or alcohol.

Lactic Acid Fermentation

A process occurring in oxygen-starved muscle cells producing lactic acid.