Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology > Media > Flashcards

Media Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Pure culture

A

population of cells arising from a single cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

who developed pure culture isolation

how?

A

Koch

  • Earlier used potato slices, then gelatin
    Many organisms can digest gelatin and it melts at 37°C
  • Later used agar (from seaweed)
    Revolutionised microbiology
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Advantages of using agar as media

A

Melts at 90-96°C, sets at about 45°C

  • Rarely digested by bacterial enzymes
  • Can incubate at higher temperatures, without agar melting
  • Can add antibiotics, blood etc to molten agar at 46-50°C
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Plating methods

A

Streak plates - Spread a culture to isolate separate cells
Ensure purity or to separate mixtures

  • Diluted by streaking with a flamed loop
  • Individual cells, each grow into one isolated colony
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Streak plates method

A 
Collect sample on sterile loop
Smear onto part of plate
FLAME AND COOL LOOP
Streak 4 lines on plate
FLAME AND COOL LOOP
Streak 4 lines on plate
FLAME AND COOL LOOP
Streak 4 lines on plate
Use up rest of plate with streak

Only touch first streak once

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Requirements for laboratory culture

A
  • Solid or liquid medium
    = Must supply all the nutrients a microbe needs
  • Different microbes have different needs
    = Knowledge of normal habitat can help

-Specialised media grows specific microbes
= Isolation of clinical pathogens, or in food, water
= Hydrocarbon utilisation
= Growth low pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Defined media

A
  • chemically defined
  • concentration of each constituent known
  • specific source of CHNOPS + ions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Support growth media for BG-11 - cyanobacteria

A

Added CO3^2- for photosynthesis

  • it is a photoautotroph, CO3 provides CO2 for photosynthesis
  • Identify- CHNOPS, K, Ca, Mg and trace metals
  • Final pH 7.4
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Support growth media for E. coli growth medium

A

Glucose minimal medium – controlled C-source

  • As it is a chemoorganoheterotroph – using glucose as C and energy source; ammonium as N source
  • require high levels of each component for growth, in particular P.
  • No amino acids provided, as it synthesise own
  • Final pH 7.0
  • Change C- source/ omit Fe to study effect
  • Test mutants for utilisation of Cho, synthesis of amino acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Support growth media for CDM - Haloarchaea

A

High salt concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Uses of defined media

A

Selectivity

  • Specific carbon sources
  • Limits to other nutrients

Use selective media to “enrich” specific organisms
- effective isolation media eg bacteria capable of degrading oil or mutants unable to utilize a specific C-source

Also used to assay compounds by monitoring growth eg Vitamin assay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

To isolate bacteria that rapidly devour hydrocarbons in oil spill:

What would you put in the growth media?
To develop a spray using oil degrading- bacteria– what nutrients would you add to the spray?

A

Oil/ Hydrocarbon as sole carbon source. Plus source N, S, P etc.

If eventually used as spray need to ensure good supply of N,S and P for rapid growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Complex media

A

= Components of undefined composition (unknown)

  • Include digested proteins (casein)
  • Extracts of complex substances (Beef extract, Yeast extract)

= General purpose media supply needs of many different microbes
- Nutrient broth, trypticase soya broth

= Additives for enriched media

  • blood to support growth of pathogens
  • Low pH eg Malt agar pH 6.0, lactic acid bacteria, yeast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Complex media is useful when

A

when growth requirements are not known or for optimal growth, show composition of MacConkeys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Selective media

A

Favour growth of particular organisms, inhibit growth of others

  • Specific substrates
  • Inhibitors
  • pH eg Malt agar
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Differential media

A
  • Distinguish between organisms

- Can allow tentative identification

17
Q

MacConkey agar

A

a selective and differential medium
with casein / animal tissue / Lactose / Bile salts / NaCl / Neutral red / Crystal violet

Selection - Bile salts (inhibitor)
: selects for bacteria able to grow in the gut (coliforms)

Differentiation - Lactose + pH indicator : lactose fermenter –pink (eg Escherichia coli)
Non-lactose fermenter – white (eg Salmonella spp.)

18
Q

How to ckeck the quality/ safety of the source of drinking water?

A

Quantitate - the heterotrophic, aerobic colony count

Estimate faecal contamination

19
Q

How to estimate faecal contamination

A

using MacConkey broth (E. coli as an indicator) – acid and gas production following growth at 37C

20
Q

Anaerobic chamber

A
  • Vacuum pump + N2 purges
  • Palladium catalyst and hydrogen to remove remaining O2
  • Interchange compartment to prevent exposure to O2
21
Q

Purity checks

A

Single colony and cell form
No extra growth on non-selective media
[same bacteria will give same colony and cell form under same growth conditions]

22
Q

Anaerobic jar

A

growth in absence of O2

O2 removed from chamber by combineing with H to form H2O, catalyzed by palladium pellets

Water is added to chemicals in envelope to generate H2 & CO2. Carbon dioxide promotes more rapid growth of microbes.

Methylene blue becomes colourless in absence of O2

23
Q

Solid growth medium

A
  • Agar plates – growth medium mixed with solid support (agar)
  • Used for general maintenance of cultures
  • Used for separating mixed cultures
  • Small scale growth of bacteria
24
Q

Growth in liquid culture

A

Batch culture

Continuous culture

25
Q

Batch culture

A

a closed system culture of microorganisms of finite volume with specific amounts of nutrients and environmental conditions.

Only a few generations are possible before nutrients are depleted.

26
Q

Bacterial growth

A

Lag phase
log phase/ exponential phase
Stationary phase
Death phase

27
Q

Lag Phase

A

When innoculated cells usually do not start to grow immediately

Cells are synthesising new cellular material

Innoculated cells often depeleted in energy and essential cellular components (e.g. ATP, ribosomes, enzyme cofactors)

Need to prepare for growth

28
Q

Log (exponential) Phase

A

= Cells are growing at maximum rate
For many this is exponential
Culture is mostly chemically and physiologically uniform
Ideal for biochemical/physiological studies

= Balanced growth
All cellular components in balance
In up-shift or down-shift balance is disturbed
Growth decreases until balance resumed

29
Q

Stationary phase

A

Possible causes:

  • Nutrient depletion
  • Build-up of toxic waste-products, e.g. Acid production during fermentation
  • Population reaches a maximal size (quorum sensing)

Once growth stops:
- Continued growth balanced by cell death or no growth but still metabolic activity

30
Q

Death phase

A

Number of viable cells slowly declines

  • Can be logarithmic
  • Dependent upon conditions

Death rate can slow as numbers decrease
- Survival of resistant cells

31
Q

Continuous culture

A

a culture of microorganisms in a medium which is maintained under constant environmental conditions with a constant nutrient supply so that it can grow over an extended period of time.

Achieved in a chemostat -Steady state conditions.

32
Q

Maintenance of steady state conditions.

A

Media fed into the chemostat at a steady rate.

Biomass and spent media removed from chemostat at the same steady rate.

Bacterial growth phase maintained.

33
Q

Batch culture Advantages

A

Versatile: can be used for different reactions every day.

Safe: can be properly sterilized.
Little risk of infection or strain mutation.

Complete conversion of substrate is possible

34
Q

Batch culture Disadvantages

A

High labour cost: skilled labour is required.

Much idle time: Sterilization, growth of inoculum, cleaning after the fermentation.

Safety problems: when filling, emptying, cleaning.

35
Q

Continuous culture Advantages

A

Works all the time: low labour cost, good utilization of reactor.

Often efficient: due to the autocatalytic nature of microbial reactions, the productivity can be high.

Automation may be very appealing.

Constant product quality.

36
Q

Continuous culture disadvantages

A

Often disappointing: promised continuous production for months fails due to a. infection. b. spontaneous mutation of microorganisms to non producing strain.

Inflexible: can rarely be used for other productions without substantial modification.

37
Q

Measurement of Culture Density

A

Counting plate: Plate serial dilutions of known volumes and count number of colonies.

Counting haemocytometer: a thick glass microscope slide with a known volume of culture placed on it.

Measure optical density (must count first).

Microbiology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions