Applied Microbiology

Question 1

Application of Microbiology is

Answer 1

Commercial use of microorganisms

Question 2

2 fields of it are

Answer 2

Food microbiology

Industrial microbiology

Question 3

Food microbiology is

Answer 3

use of microbes in food production and the prevention of food spoilage and food related illnesses

Prevent food related illnesses
– Prevent contamination from pathogens
– Treat food product to kill pathogens

Prevent food spoilage
– Food spoilage microbes reduce quality of food
– Reduce shelf life of food

Question 4

Food microbiology is

Answer 4

application of microbes to industrial manufacturing processes and the solution of environmental, health, and agricultural problems, molecular micro.

Question 5

What is food spoilage

Answer 5

Food made unpalatable through injury or damage (made unacceptable)

Changes in food characteristics (organoleptic) 
– Appearance: colour, gas pockets, foam
– Odour
– Taste or flavour
– Texture
– Slime formation

Question 6

What causes food to spoil

Answer 6

– Insect and rodent infestation
– Physical damage: bruising, freezer burn, drying, pressure
– Enzyme activity
– Chemical damage: oxidation of fat (rancidity)
– Microbial growth (most common) including bacteria, moulds and yeast.
– Under ideal conditions bacteria predominate - shorter generation times

Question 7

Microbial growth and spoilage

Answer 7

• Spoilage appears to be rapid onset
• Due to exponential growth pattern microbes
• Initial population is mixed
• Microbe with shortest generation time under the conditions of storage will dominate.
• Bacteria will dominate over moulds and yeast.

Question 8

Decay and Putrefaction

Answer 8

Spoilage is a natural activity of microbes attempting to obtain nutrients for growth.

Aerobic microbial spoilage is decay.

Anaerobic microbial spoilage is putrefaction.

Question 9

Disease transmission + food spoilage

Answer 9

Diseases acquired from food
• direct effects of microbes (infections)
• toxins
• microbial action on food

increase Spread of foodborne pathogens due to industrialization
– Food sources from different parts of
world
– Contamination not confined to a single area

Question 10

microorganism as food (yeats, fungi, algae) and their advantage

Answer 10

• Yeasts - source of protein and vitamin
• Fungi - mushrooms
• Algae - direct food

Advantages: grow fast, good protein content, save environment

Question 11

food preservation methods

Answer 11

1. Prevent microbial contamination
2. Microbial growth and activities inhibition
3. Destroy/remove microbes from food

Question 12

benefits of fermentation

Answer 12

• Oldest method of food processing
• Increase shelf life and safety of product
– High acid and salt, bacteriocins
– Preserves food by inhibiting spoilage bacteria
• Enhance aroma, texture, flavor
– grape juice –> wine; milk –> cheese

• Improve digestibility, nutritional content

Question 13

why treat waste

Answer 13

• Remove pathogens: bacteria, viruses, eggs and cysts of parasitic worms
• Remove toxins: metals, pesticides, herbicides
• Prevent contamination of drinking water
• Prevent foul odours: H2S, amines, oil and grease scum
• Remove nutrients that cause pollution

Question 14

what is BOD stand for

Answer 14

biochemical oxygen demand

Question 15

biochemical oxygen demand is and what do

Answer 15

• Determine the levels of biological degradable organic material present in water
• This test relies on the amount of oxygen required by microbes to remove (degrade) these organic compounds
• Measure decreases in oxygen concentrations following the oxygen dependent oxidation of organic compounds by bacteria
• High BOD indicates high levels of organic material in water tested

Question 16

waste water treatment - primary

Answer 16

Physical process, remove larger solid and insoluble objects

Storm water drainage and sewage are separate in Australia (most developed countries)

Question 17

waste water treatment - secondary

Answer 17

Microbial digestion of organic material
Hydrolysis (slow – rate limiting step):
• Reaction where complex macromolecules are split into smaller parts
• Hydrolysis by exo-enzymes produced by microbes
– Proteins broken down to amino acids by proteases
– Carbohydrates broken down to simple sugars by amylases
– Fats and oils broken down to long chain fatty acids by lipases

Question 18

waste water treatment - tertiary

Answer 18

– Physical and chemical methods used

– Potable (Drinkable) Water

Question 19

uses of bacteriophages

Answer 19

Possible treatment for bacterial infection?
– Phage quickly removed from body by immune system
– Some experiments continuing in Russia and Georgia

Identify pathogenic bacteria (Phage typing)
– Phage specific for bacteria
– Salmonella, Staphlococcus

Recombinant DNA technology
– Insert gene into plasmid, deliver plasmid to bacteria via phage
– Bacteria produces desired product