Fermentation Technology Quiz

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Questions and Answers

Which of the following is NOT a requirement for an effective fermenter?

Control the pH of the culture

Maximize contamination levels (correct)

Minimize liquid loss from the vessel

Allow feeding of nutrient solutions and reagents

What is the primary purpose of agitation in fermenters?

To mix the three phases within a fermenter (correct)

To increase the temperature of the liquid

To eliminate the need for oxygen

To minimize the growth of microorganisms

Which type of fermenter uses compressed gas for mixing?

Batch fermenter

Continuous flow fermenter

Airlift fermenter (ALF) (correct)

Stirred Tank Reactors (STRs)

What component in a stirred tank reactor aids in mass transfer?

Baffle plates Signup and view all the answers

What is the main disadvantage of using shake flask fermentations?

Limited scale-up potential Signup and view all the answers

Which of the following factors is crucial to maintain during fermentation aside from agitation?

Control the temperature Signup and view all the answers

In the context of fermentation, the liquid phase in a fermenter primarily contains what?

Dissolved nutrients and metabolites Signup and view all the answers

What is one key function of the impeller in a stirred tank reactor?

To drive the stirrer system for mixing Signup and view all the answers

What initiates liquid movement in airlift fermenters?

Injection of compressed air Signup and view all the answers

What causes the upward movement of liquid in an airlift reactor?

Density difference between riser and downcomer Signup and view all the answers

What is a key advantage of using airlift fermenters over mechanically agitated reactors?

Reduced heat generation Signup and view all the answers

What mechanism do deep-jet fermenters use to mix contents?

Liquid kinetic energy Signup and view all the answers

How is efficient heat transfer achieved in fermenter design?

Surrounding with an outer jacket or via internal coils Signup and view all the answers

Why is aeration important in most fermentations?

To provide large quantities of sterile air or oxygen Signup and view all the answers

Where is the sparger typically located in stirred tanks to promote aeration?

Directly below the agitator Signup and view all the answers

What should be done when fermentations operate above ambient temperature?

Input additional heat to support metabolism Signup and view all the answers

What characterizes a batch fermentation system?

No additions following inoculation except for some components Signup and view all the answers

Which of the following are disadvantages of batch fermentation?

Slower growth rate due to nutrient decline Signup and view all the answers

What is a benefit of fed-batch fermentation?

Increased nutrient volume reduces toxicity Signup and view all the answers

In continuous fermentation, what is a primary disadvantage?

Constant loss of large volumes of product Signup and view all the answers

What distinguishes solid state fermentation (SSF) from liquid state fermentation (LSF)?

SSF uses solid support while LSF is based on liquid media Signup and view all the answers

What type of products can be manufactured using solid state fermentation?

Pharmaceuticals like antibiotics and enzymes Signup and view all the answers

Which of the following is a feature of continuous fermentation?

It maintains a steady state where nutrient concentration is stable Signup and view all the answers

What is the primary concern in a fed-batch fermentation system?

Increased chances of contamination Signup and view all the answers

What is a key characteristic of solid state fermentation (SSF)?

It involves the growth of microorganisms on solid support. Signup and view all the answers

Which of the following is NOT an advantage of solid state fermentation?

High levels of liquid waste production. Signup and view all the answers

Which type of culture is involved in straw bioconversion?

Dual culture. Signup and view all the answers

What is the first step in the solid state fermentation process?

Pretreatment of a substrate. Signup and view all the answers

What is a common product generated from solid state fermentation?

Mushrooms. Signup and view all the answers

How is the hydrolysis of substrates primarily achieved in SSF?

By enzymatic actions on polymeric substrates. Signup and view all the answers

What kind of materials are typically used in solid state fermentation?

Solid substrates like cereal grains and straws. Signup and view all the answers

Why do fungi perform better than bacteria in solid state fermentation?

They thrive in low moisture conditions. Signup and view all the answers

What is a primary advantage of tray bioreactors in solid-substrate fermentation?

Effective oxygen transfer Signup and view all the answers

Which feature is characteristic of packed bed reactors (PBR)?

Immobilized microbial cells act as biocatalysts Signup and view all the answers

How does a fluidized bed reactor (FBR) achieve mixing of solid particles?

Through continuous forced aeration Signup and view all the answers

What is a disadvantage of using a rotating drum bioreactor?

Limited substrate capacity Signup and view all the answers

What role does heat removal play in solid-substrate fermentation?

It regulates microbial growth and activity Signup and view all the answers

What is a common use of bed systems in solid-substrate fermentation?

Wastewater management Signup and view all the answers

How are humidity levels controlled in tray bioreactors?

By circulating humidified air throughout the chamber Signup and view all the answers

In what way does the design of fluidized bed reactors prevent substrate particle aggregation?

Through the application of forced air Signup and view all the answers

What is the primary focus of upstream processing (USP) in fermentation?

Processes leading to fermentation Signup and view all the answers

What type of metabolites are produced during the active growth of microorganisms?

Primary metabolites Signup and view all the answers

Which of the following is NOT a characteristic of primary metabolites?

Determined by microbial activity alone Signup and view all the answers

What is the main goal of downstream processing (DSP) in fermentation?

To recover products safely and efficiently Signup and view all the answers

Which aspect is critical in the optimization of fermentation media?

Cost-effective carbon and nutrient sources Signup and view all the answers

Secondary metabolites are best defined as?

Not central to the organism's developmental processes Signup and view all the answers

What is the primary aim of strain improvement in fermentation processes?

To improve yield and productivity Signup and view all the answers

Which of the following is NOT a product derived from fermentation?

Glucose Signup and view all the answers

Study Notes

Biotechnology (PMP-404) Level 4 Pharm D

Lecture 2 and 3 cover solid state fermentation (SSF)
Objectives for Lecture 2: identify basic parts of fermenters, methods for controlling conditions inside, differentiation between fermentation types

Fermenter Specifications

Requirements for fermenters include minimizing liquid loss, avoiding contamination, ensuring adequate mixing and aeration, maintaining specific temperature, controlling pH of the culture, promoting growth of wider organism range, and enabling nutrient/reagent feeding

Major Parts of Fermenter

Impellers
Baffles
Inoculation port
Sparger
Sampling point
pH control device
Temperature control system
Foam control device
Bottom drainage system

Submersion Fermentation Techniques

1. Batch: Closed system; no additions except acid/base, air & antifoam after inoculation; has definite start/end; product harvested, fermenter cleaned before restarting
- Advantages: low contamination chance
- Disadvantages: slower growth rate, more downtime, variability
2. Fed-Batch: Semi-closed; continuous nutrient additions; product remains until run's end;
- Advantages: useful if substrate causes viscosity problems or toxicity at high concentration
- Disadvantages: high contamination risk
3. Continuous: Open system; continuous nutrient addition and product removal at same rate; results in constant volume; reaches a steady state;
- Advantages: faster growth rate
- Disadvantages: high contamination risk, product loss

Control of Chemical and Physical Conditions

1. Agitation: Mixing three phases - liquid, gaseous (O2, CO2), solid.
2. Heat transfer: Generated by metabolic activity and agitation. Effective heat transfer is crucial for temperature control. Use outer jacket or internal coils.
3. Aeration: Most fermentations are aerobic. Sterile air/oxygen enters through a sparger system, which is usually located below the agitator in stirred tanks.

Types of Fermenters

a) Stirred Tank Reactors (STRs): Mechanically moving agitators/impellers within a baffled cylindrical vessel.
b) Airlift Fermenter (ALF): No moving parts, using compressed air at the bottom to create mixing from density difference in the riser and downcomer regions.

Solid State Fermentation (SSF)

Growth of microorganisms on solid support without much water.
Supports used: cereal grains (rice, wheat, barley, corn), legume seeds, straws, sawdust.
Products include: food (cheeses, mushrooms), fuel, pharmaceuticals (antibiotics), enzymes, organic acids, ethanol
Bioreactors for SSF are typically batch processes, though fed-batch and continuous systems are being developed.

SSF Advantages

Low contamination, minimal waste/effluent, simple technology, high product yield, easy bioreactor design.

SSF Disadvantages

Lower growth rates, increased non-productive downtime, variability of product yield, less efficient compared to other methods

Bioreactors for SSF

1. Tray bioreactor: Tray tops are open; bottoms and sides are perforated, allowing aeration; substrate is spread thinly and stacked in a chamber with humidified air circulation. Temperature control with worm/cold water circulation. Scale up achieved increasing tray area. Used for most fermented food/enzyme production.
2. Two-Bed systems: Solid substrate bed up to about 1m deep; humidified air is continuously forced through.
2.a) Packed bed reactor (PBR): Tubular reactors packed with immobilized cells using top or bottom feed with nutrients; uses forced aeration. Uses include waste water management
2.b) Fluidized bed reactor (FBR): Particles behave as a liquid; forced aeration at the bottom chamber creates mixing; used for continuous operation, prevents adhesion between particles.
3. Rotating drum bioreactor: Semi-filled drum that rotates to mix the substrate, with air circulation around the bed. Substrate bed depth is limited for effective oxygen/CO2 transfer (and baffles might be incorporated)

Stages of Fermentation

Upstream Processing (USP): Involves microorganism selection and improvement, establishing suitable medium, optimization to maximize yield
Downstream Processing (DSP): Includes cell harvesting, product purification, and other finishing processes

Microbial Metabolites

Primary metabolites: Essential for organism growth, development, reproduction, central metabolites, formed in large quantities during cells' active growth; easy extraction
Secondary metabolites: Do not play role in cell development/reproduction; observed in some microorganisms; ecological function; formed in smaller quantities, with difficult extraction

Phases of Metabolites Production in Batch Culture

Phase 1 (Trophophase): Nutrients sufficient; exponential growth, no product formation
Phase 2 (Idiophase): Carbon limitation; growth slowing or stopped; product formation and harvesting occurs
Phase 3 (Senescence): Product formation stopped, degradation starts

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Description

Test your knowledge on the essential components and functions of different types of fermenters. This quiz covers various aspects of fermentation technology, including agitation, mass transfer, and heat transfer mechanisms. Perfect for students and professionals in biotechnology and chemical engineering.