Topic 6 - (Microbiology and pathogens) Microbial Techniques

Question 1

Microbial Techniques:

4 ways of measuring growth:

Answer 1

• cell counts
• dilution plating
• area + mass of fungi
• optical methods

Question 2

Ways of measuring growth:

Cell Counts?

Answer 2

• bacteria + single elled fungi cultered in nutrient broth
• counted using a microscope + haemocytometer

Question 3

Ways of measuring growth:

Dilution plating?

Answer 3

• used to find total viable cell count
• culture diluted until colonies can be counted

Question 4

Ways of measuring growth:

Area + mass of fungi?

Answer 4

• diameter measured + compared or mass found from centrifugation

Question 5

Ways of measuring growth:

Optical methods?

Answer 5

• the amount of light that can pass through a culture is measured

Question 6

2 problems with culturing microorganisms?

Answer 6

• mutant strain may arise that’s pathogenic
• pathogens from enviroment may contaminate

Question 7

How are microorganisms cultured?

Answer 7

Aseptically

Question 8

Describe the Aseptic culture technique:

Answer 8

• ## obtain the microorganism you want to culture

Question 9

What are the 4 phases of microorganism growth?

in order

Answer 9

lag
log
stationary
death

Question 10

4 phases of microorganism growth and what they mean

Answer 10

lag - microorganisms are adjusting to environment before reproducing
(means the pop wont increase at max in log phase)
log - pop size grows exponentially - every round of division doubles pop size. suffiecient number of nutrients
stationary - pop = maximum due to decreased nutrient levelsand build up of toxic substances
death - lack of nutrients ^ toxicity in products + death of organisms

Question 11

Aseptic culture technique

what are the appropriate nutrients in a broth?

Answer 11

minerals/nitrogen/carbon

The medium also needs to be enriched in potein from a blood/yeast/meat extract

Question 12

Some microorganisms need a very specific combination of nutrients and therefore need to be grown in a selective medium (containing a very specific balance of nutrients) - Why is this useful?

Answer 12

• this meany only specific bacteria will grow in it and e.g mutant strains won’t

Question 13

streak plate:

process of inoculating?

Answer 13

streak plate:
* steralise inoculating loop by flaming (blue)
* dip in culture
* sterile plate
* at least 3 streaks straight or zig zag, turn, streak which must overlap from first streak, turn, streak to obstain single colonies

Question 14

spread plate:

process of inoculating?

Answer 14

spread plate:
* drop some on and use a sterile spreader to distribute it
If looking for single colonies: then incubate the plate and use an inoculating loop to take off individual colonies

Question 15

What conditions do broths produce?

Answer 15

Anoxic conditions

Question 16

what does anoxic mean?

Answer 16

a place or environment lacking oxygen

Question 17

anoxic vs hypoxia

(not needed but just for just)

Answer 17

• The complete lack of oxygen delivery to an organ
• Hypoxia - when an organ experiences oxygen delivery that is insufficient to meet the metabolic needs of the tissue