L4: Centrifugation

Question 1

Which microorganisms produce most industrial enzymes?

Answer 1

Bacteria and fungi

Question 2

What bulk enzyme is low priced and low molecular weight(MW)?

Answer 2

Succinic acid

Question 3

What bulk enzymes are high priced and high molecular weight (MW)?

Answer 3

1. Human growth hormone
2. Monoclonal antibodies

Question 4

What is the equation for the sigma factor?

Answer 4

Q=ug*∑

Q is the throughput (m3/s)
∑ has units of m2 and is equivalent to the cross sectional area of a settler with the same capacity

Question 5

What is the equation for the sigma factor for bowl centrifuge?

Answer 5

∑=piω^2(R^2-rc^2)H/gln(R/r)

ω is the angular velocity (rad/s)
R is the outer radius of the bowl (m)
rc is the radius of the clarified discharge weir (m)
H is the height of the bowl (m)
r is the inner radius of the liquid in the bowl (m)
g is the acceleration due to gravity (m/s2)

Question 6

What is the Disc Stack Centrifuge Capacity formula?

Answer 6

∑=(2/3)piω^2n(R^3-rc^3)/g*tanθ

ω is the angular velocity (rad/s)
n is the number of discs
R is the outer radius of the discs (m)
r is the inner radius of the discs (m)
θ is the angle between disc and vertical (rad). Radians = Degrees × π/180°
g is the acceleration due to gravity (m/s^2)

Question 7

What are the main industries that use industrial enzymes, and what purposes do they serve?

Answer 7

Food (bread, dairy, fruit juice), textile (fabric treatment), detergent (low-temp washing), pulp/paper (bleaching), animal feed (absorption), and leather (dehairing).

Question 8

What are the primary microorganisms used for enzyme production?

Answer 8

Aspergillus, Trichoderma, Bacillus, and Kluyveromyces.

Question 9

What is the primary goal when producing industrial enzymes?

Answer 9

To optimize production costs, achieve high yields, and maintain enzyme stability.

Question 10

What are the main stages in the enzyme production process?

Answer 10

Fermentation, downstream processing (DSP), and formulation.

Question 11

Explain the difference between intracellular and extracellular enzyme production.

Answer 11

Intracellular requires cell disruption for enzyme recovery; extracellular is secreted but may require protection from proteases.

Question 12

Why is extracellular enzyme production preferred

Answer 12

It avoids the need for cell disruption, simplifying recovery and reducing costs.

Question 13

What is the typical size and volume of fermentation tanks used in industrial enzyme production?

Answer 13

Tanks of up to 100 m³ with an operating volume of 80 m³.

Question 14

What are the primary techniques for separating cells after fermentation?

Answer 14

Centrifugation and filtration.

Question 15

Describe the function of a disc stack centrifuge in enzyme production.

Answer 15

It separates cells from the liquid phase, isolating extracellular products with high clarity.

Question 16

What is the purpose of the sigma factor in centrifugation?

Answer 16

It helps calculate the capacity of a centrifuge based on its geometric and operating parameters.

Question 17

Why are high-throughput disc stack centrifuges preferred over microfiltration in some processes?

Answer 17

They handle larger volumes, are faster, and work well for separating cells from the liquid phase.

Question 18

What is the role of ultrafiltration in the purification process?

Answer 18

It removes smaller proteins, sugars, and salts, concentrating the enzyme product.

Question 19

List some of the primary costs in enzyme production.

Answer 19

Raw materials, equipment, labor, utilities, and product recovery.

Question 20

What does the process scale in enzyme production depend on?

Answer 20

Market demand, typically estimated to produce around 500 tons per year.

Question 21

What are the challenges of maintaining sterility in centrifugation?

Answer 21

The need to prevent contamination, manage cooling, and control residence time.

Question 22

What factors affect particle settling during centrifugation?

Answer 22

Weight, drag of the fluid, buoyancy, and particle size (Stokes Law).

Question 23

Describe the purpose of precipitation in enzyme recovery.

Answer 23

To separate insoluble proteins from soluble proteins through pH adjustment or the addition of salts.

Question 24

What are the main goals in the formulation stage of enzyme production?

Answer 24

Achieving product stability, matching recovery yield, and ensuring product delivery specifications.

Question 25

Why might Solid-State Fermentation (SSF) be used less frequently than Submerged Fermentation (SmF)?

Answer 25

SSF is suitable for few applications due to limited scalability and higher operational complexity.

Question 26

How does scaling up fermentation improve cost-efficiency in enzyme production?

Answer 26

Larger fermenters allow economies of scale, reducing costs per unit of enzyme produced.