Week 3-4 Blended Learning Sterilization and Solid Substrate Fermentation

Question 1

Sterilization

Answer 1

Control/prevention of undesired growth of microbial cells. Sterilization completely destroys all viable organisms including spores and may be performed using heat, radiation, chemicals, or by physical removal of cells. The undesired population decreases exponentially; several factors influence the effectiveness of the process

Question 2

Factors that effect the sterilization process

Answer 2

-Population size
-Population composition (age, morphology, physiological conditions)
-Concentration of the antimicrobial agent or the intensity of the treatment
-Period of exposure to the lethal agent
-temperature
-Environmental conditions (pH, viscosity)

Question 3

Sterilization can be applied by heat

Answer 3

-Incineration 500C
-Moist heat (steam pressure at 121 C for 15 minutes)
-Dry heat (higher temp, longer time 160*C, 2 hrs)

Question 4

Probability of contamination for Sterilization?

Answer 4

Needs to occur so that typically the probability of contamination is 0.1% (1 in 1000).

Question 5

Why is keeping a consistent temperature important for sterilization?

Answer 5

It’s important to be careful not to degrade the substrate (protein denaturation

Question 6

What is the objective of sterilization?

Answer 6

The aim of sterilization is to provide the conditions that give an acceptable probability of contamination of 0.1% (1 in 1000)

Question 7

Solid Substrate Fermentation

Answer 7

-More common in Asia than in North America and Europe
-Solid substrate fermentation involves the growth of microorganisms on solid, normally organic, materials in the absence or near absence of water

-Typical substrates and products include:

Substrates: Cereal grains, legumes, lignocellulosic material such as straw, wood chippings

Products: mushrooms, cheeses, tofu, spores of conithyrium minitans (biocontrol of plant pathogens)

Question 8

What are important parameters that affect solid substrate fermentation?

Answer 8

-Water activity (low-growth reduced and too high- lower O2 transfer)
-Temperature-heat generation (influences relative humidity)
-Aeration-required to provide oxygen and to remove heat

Question 9

What are the advantages of Solid Substrate fermentation

Answer 9

-Low cost media
-Superior productivity
-Simple
-Low capital costs
-Reduced energy requirements
-Low waste water output
-No problems with foaming

Question 10

What are the disadvantages of Solid Substrate Fermentation?

Answer 10

-It lacks the sophisticated control mechanisms associated with most liquid base fermenters
-Slower microbial growth
-Heat build up
-Bacterial Contamination
-Difficult to scale up
-Substrate moisture level difficult to control

Question 11

What are the Solid Substrate Fermentation Process Steps?

Answer 11

-Pretreatment of substrate
-Hydrolysis of polymeric substrate material (polysaccharides, proteins)
-Utilization of hydrolysis products
-Separation and purification (downstream processing)

Question 12

Bioreactors used in solid substrate fermentation?

Answer 12

Rotating drum fermenter, tray fermenter, bed systems (column bioreactors, fluidized bed reactors)

Question 13

Rotating drum fermenter

Answer 13

-Bioreactor used in solid substrate fermentation, used for enzymes and biomass

Question 14

Tray fermenter

Answer 14

-Bioreactor used in solid substrate fermentation, used for food and enzymes

Question 15

Column bioreactors

Answer 15

-Bioreactor used in solid substrate fermentation, it is a bed system and used for organic acids

Question 16

Fluidized bed reactors

Answer 16

-Bioreactor used in solid substrate fermentation, it is a bed system and used for biomass production

Question 17

Process Control

Answer 17

There are 3 fundamental components to the process control includes: a sensor, controller, and actuator

Question 18

Sensor

Answer 18

Measures a process variable, converts environmental variable into a quantifiable signal (often an electrical signal that is generated and sent to controller)

Question 19

Controller

Answer 19

-Normally a computer or a microprocessor, it accepts process variable from sensor and it will compare the given process variable to the setpoint, the user would correct the setpoint on the controller, if process variable not same as setpoint then the controller sends electrical signals into actuator

Question 20

Actuator

Answer 20

-Actuates an action, for example a pH meter that measures the concentration of hydrogen ions from sensor, if the pH is not the same as the setpoint then the controller would produce an output and the pump that would add the acid or the base would be filling one of these reagents into the chemical or biotech process.

Question 21

Bioreactor system

Answer 21

-Has 3 components: A reactor vessel, bioconsole, and biocontroller

Question 22

Bioconsole

Answer 22

-A type of actuator

Question 23

Biocontroller

Answer 23

-Is a type of controller (has a computer)

Question 24

Bioreactor has 3 types of sensors what are they?

Answer 24

-Dissolved oxygen, pH probe, and a thermocouple (measures temperature of process)