Lecture 2 - Jennifer Culturing Microbes

Question 1

function of aseptic technique

Answer 1

To prevent contamination

Question 2

Before handling and growing microbes what is required

Answer 2

A sterile growth media

Question 3

What is the Latin meaning for “medium”

Answer 3

Middle

Question 4

Name the types of medium

Answer 4

•liquid
•water based (broth)
•solid (agar petri plates)

Question 5

Name the common methods of sterilising bacterial growth media

Answer 5

•boiling
•autoclave
•dry heat

Question 6

Write a short note on boiling

Answer 6

100 degrees celcius
For 30 minutes
Kills cells

Question 7

Write a short note on autoclave

Answer 7

121 degrees celcius
For 30 minutes
Kills all cells and spores

Question 8

Write a short note on dry heat

Answer 8

150 degrees celcius
For 120 minutes
Kills all cells and spores

Question 9

Name the five l’s for handling microorganisms

Answer 9

1.Innoculation
2.Incubation
3.Isolation
4.Inspection
5.Identification

Question 10

Growth in a nutrient broth can be observed as what kind of suspension

Answer 10

A cloudy suspension

Question 11

What is a cloudy suspension in a nutrient broth termed as

Answer 11

A culture

Question 12

What temperature does agar melt at

Answer 12

100 degrees Celsius

Question 13

What temperature does agar solidify at

Answer 13

40 degrees Celsius

Question 14

Name the method used to sterilise agar

Answer 14

Autoclaving

Question 15

What do bacteria grow as on agar

Answer 15

Colonies

Question 16

Each bacterial colony is derived from what

Answer 16

A single cell

Question 17

Single colony purification =

Answer 17

Single bacterial cell purification

Question 18

Where are microorganisms grown

Answer 18

In an incubator

Question 19

What makes an incubator suitable for growing microorganisms

Answer 19

It provides optimal temperature and gas content

Question 20

What does an incubator speed up

Answer 20

The process of multiplication and production of a culture

Question 21

How many different media for growing bacteria

Answer 21

> 500

Question 22

What do different colony types mean

Answer 22

The culture is not pure

Question 23

Disadvantage of broth culture

Answer 23

Not possible to determine if growth of more than one bacterial species has occurred

Question 24

Name identification methods for microorganisms

Answer 24

•Macroscopic or colony morphology
•Microscopic morphology
•biochemical characteristics
•genetic characteristics

Question 25

Define sterilisation

Answer 25

Removal and destruction of all microbes in or on an object

Question 26

Describe physical heat method for the disposal of cultures

Answer 26

•moist heat,boiling, flowing steam Cells and most viruses - not spores •Tyndallization - intermittent boiling •steam (autoclaving) 121 degrees celcius for 15-30 minutes All spores , viruses , cells , media and equipment •dry heat ( hot air) 1 hour at 171 degrees •incineration (burning) 1 second or more at 1000 degrees celcius

Question 27

Describe radiation methods for disposal of cultures

Answer 27

•Ionising eg- x rays , gamma rays , secs-hrs , OH- radicals , damage to DNA •sterilise pharmaceuticals and medical supplies •non ionising eg- UV light ,DNA damage , operating theatres , kitchens

Question 28

Name gaseous avengers used for chemical sterilisation methods

Answer 28

Ethylene oxide

Question 29

What causes cell death in chemical sterilisation methods

Answer 29

EtO alkylates Nucleic acids Proteins Enzymes

Question 30

How long are cycles for chemical sterilisation methods

Answer 30

12 - 24 hours

Question 31

What is ethylene oxide sterilisation commonly used for

Answer 31

Sterilisation of surgical equipment in hospitals

Question 32

Write a short note on pasteurisation

Answer 32

Use of heat 75 degrees celcius for 15 seconds Kill pathogens and reduce number of spoilage microorganisms in good and beverages ( milk , fruit juice , wine , beer)

Question 33

What are antiseptics

Answer 33

Microbicidal agents harmless enough to be applied to skin and mucous membrane

Question 34

Examples of antiseptics

Answer 34

Mercurials Silver nitrate Iodine solution Alcohols Detergents

Question 35

What are disinfectants

Answer 35

Agents that kill microorganisms but not necessarily their spores not safe for application of living tissues they are used on inanimate objects like tables,floors

Question 36

Example of disinfectants

Answer 36

Chlorine Hypochlorites Chlorine compounds Copper surface Quaternary ammonium compounds

Question 37

What are disinfectants and antiseptics distinguished on the basis of

Answer 37

Whether they are safe for application to mucous membranes Safety often depends on concentration of compound Eg: sodium hypochlorite (chlorine) as add to water is safe for drinking but chlorox (5% hypochlorite) is an excellent disinfectant not safe to drink