Topic 13 -Applied & Industrial Microbiology I & II

Question 1

List 3 food preservation methods before industrial canning & refrigeration

Answer 1

Drying
Osmotic Pressure
Fermentation

Question 2

A bit about drying food preservation?

Answer 2

removes water, which is needed by all organisms

Question 3

A bit about osmotic pressure food preservation?

Answer 3

Uses salt or sugar

High solute concentrations can be inhibitory directly, and also lower H2O concentration.

Question 4

A bit about fermentation food preservation?

Answer 4

Adds alcohols and/or acids that inhibit many microbes

Question 5

Food preservation allows…?

Answer 5

food to be stored and helps avoid food borne diseases e.g. food poisoning by intoxication or infection

Question 6

Describe food poisoning by intoxication

Answer 6

bacteria produce a toxin that is ingested w/ the food

Question 7

Describe food poisoning by infection

Answer 7

Caused by an infectious microorganism in the food e.g. salmonella

Question 8

What is HACCP and what is the aim of this system?

Answer 8

Hazard Analysis and Critical Control Point

aimed at minimising the risk of food poisoning

Question 9

List the proactive measures used in HACCP

Answer 9

• Identifying hazards in the manufacturing process
• Identifying steps in production chain where hazards can be controlled (these are called critical control points CCP)
• Determine tolerances at these points to control the hazards
• Constantly monitor CCP’s & act if are outside of safe range

Question 10

List 7 modern food preservation methods

Answer 10

canning
freezing
preservatives
vacuum packing
freeze drying
high pressure
irradation

Question 11

Define commercial sterilisation?

Answer 11

main aim is to destroy botulinum endospores

• pathogens have been killed
• any surviving bacteria/fungi will not grow under the normal storage conditions of the can

Question 12

Define sterilisation?

Answer 12

Removal or destruction of all living organisms, incl. endospores

Question 13

List & describe the 3 main types of can spoilage

Answer 13

1. Thermophilic anaerobic spoilage: causes swelling of can due to gas production
2. Flat sour spoilage: lowered pH, sour smell, no swelling of can
3. Mesophilic spoilage: occurs if cans underprocessed (not heated high/long enough) or if there is a leakage into can after processing (hole/crack)

Question 14

Describe aseptic packaging

Answer 14

pre-sterilised materials assembled into packages and aseptically filled w/ commercially sterilised foods.

Question 15

Describe food preservation by high-energy electrons

Answer 15

irradation/ionizing -breaks DNA chains, kills bacteria & spores

Question 16

Describe food preservation by High-Pressure Processing (HPP)

Answer 16

kills microbes by disruption of enzymes and non-covalent bonds

Question 17

How is cheese a beneficial use of microoganisms?

Answer 17

Lactic acid bacteria ferment lactose to produce it.

Rennin is also used to help solidify

Question 18

How is yoghurt a beneficial use of microoganisms?

Answer 18

produced by fermentation of milk by lactic acid bacteria
-proto cooperation by streptococcus thermophilus and lactobacillus bulgarius allows this (feed each other).

consult slide on page 5.
1 produces what the other is limited by.

Question 19

How is red wine a beneficial use of micooganisms?

Answer 19

Saccharomyces cerevisiae converts sugar to ethanol & CO2

Question 20

How is vinegar a beneficial use of microoganisms?

Answer 20

ethanol converted to acetic acid by acetobactor and gluconobacter

Question 21

Define microbial biotechnology and name the two types

Answer 21

Use of microoganisms or cell components to make useful products or remove wastes.

• Classical/traditional biotech: wine, antibiotics, enzymes, chemicals, food
• Recombinant DNA tech: GMO

Question 22

Define industrial fermentation and name the vessel used for it

Answer 22

Large scale cultivation of microbes (or other cells) to produce a commercially valuable substance.
Vessel used are called bioreactors.

Question 23

What is a bioreactor?

Answer 23

vessel designed to control all aspects of cell growth to optimise conditions for production e.g. pH, temp

Question 24

What is a primary metabolite?

Answer 24

Synthesis parallels cell growth, as it is a metabolite that is produced as part of growth process
e.g. cells, aa, enzymes, end products of fermentation (ethanol)

Question 25

What is a secondary metabolite?

Answer 25

Synthesis follows AFTER CELL GROWTH (so is not needed for cell growth)
e.g. antibiotics, pigments, toxins

Question 26

Name some chemicals and medicines that use microoganisms to be produced

Answer 26

Xanthan gum
AA's
citric acid
enzymes
vitamins
pharmaceuticals
vaccines

Question 27

List 3 products of recombinant DNA technology

Answer 27

Human insulin (from E.Coli)
Human Growth Hormone (somatotropin)
Human blood clotting factors (VIII, IX)

Question 28

Human hepatitis B vaccine can be produced from…?

Answer 28

yeast cell origin. It is the first example of a vaccine produced from recombinant cells which is effective against a human viral infection

Question 29

What is biomass?

Answer 29

Organic matter produced by living organisms

Question 30

What is bioconversion?

Answer 30

Conversion of biomass to alternative energy sources (methane, ethanol, H2)

Question 31

List 3 biofuels that can be made by microoganisms

Answer 31

1. Cellulose -first needs to be digested by cellulase enzymes to sugars, then sugars fermented to ethanol or higher alcohols or hydrogen
2. Algal oils
3. Hydrogen