Bacterial Cultivation, Preservation and Innactivation Flashcards Preview

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Flashcards in Bacterial Cultivation, Preservation and Innactivation Deck (25)
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1

What is the process of bacterial reproduction?

Binary fission

2

What are the 4 growth cases of a bacteria?

Lag, exponential, stationary, decline

3

What occurs during the lag phase?

Metabolism to acquire essential constituents ready to divide

4

What happens during exponential phase?

binary fission causes exponential increase

5

What happens during the stationary phase?

Essential nutrients depleted and toxic metabolism products accumulate in media

6

What occurs during the decline phase?

Old cells die rapidly, followed by young

7

How can bacteria be quantified?

Microscopic counting, colony counting, opacity/ turbidity

8

What is a heterotroph?

bacteria that feed on pre-formed living organisms

9

What is an autotroph?

bacteria that use carbon dioxide

10

What needs to be considered for bacterial nutrition?

Large quantities of C and N, Peptones (protein) in culture media, phosphates for nucleic acid, sulphur for amino acids, Ca2+, Fe3+, Mg2+, K+

11

What are 3 microbial responses to nutritional deficiency?

Extracellular molecules collect nutrients, enter semi-starvation state, sporulation

12

What does a selective growth medium allow?

Can limit growth of unwanted microbes or growth of desired ones

13

What does differential growth media enable?

Enables differentiation between different microbes

14

What is a defined and complex medium?

Defined- known amounts of chemicals
Complex- unknown

15

What can influence bacterial growth?

Temp, Ph, Moisture, Atmosphere, Osmotic pressure

16

What is the most common temperature for bacteria growth?

37 degrees

17

What is a mesophile bacterias range of temperature?

20-45 degrees

18

What temperatures do thermophile and psycrophiles prefer?

Psyco- 15
Thermo- 60

19

What does a microaerophlile require in terms of O2?

Oxygen in small amounts

20

What are obligate, aerotolerant and facultative anaerobes?

Obligate- strict killed by O2
Aerotolerant- don't use O2 but not killed by it
Facultative- can grow with or without

21

What is a con of refrigeration, freezing, boiling and vacuum packing?

Refrigeration- some still grow
Freeze- survivors multiply rapidly when thawed
Boiling- endospores survive
Vacc- very selective

22

How is must flash pasteurised and UHT produced?

Flash- 72c for 15 seconds
UHT- 140c for 1 sec

23

What are the normal conditions of an autoclave?

121.5c dore 15 mins

24

How can things be sterilised?

Airfiltration, Gamma radiation, UV light, Chemical methods

25

What are the 5 chemicals used for innactivation?

Surfactants, Phenols, Halogens, Alcohols, Heavy metals