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mcb 11 lec > Module 3 > Flashcards

Module 3 Flashcards

1
Q
  • a culture which contains a single species of microorganism
  • a population of cells arising from a single cell
A

Pure Culture (Axenic Culture)

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2
Q
  • increasing the population of microorganisms by providing
    their nutritional and physical requirements
A

Cultivation

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3
Q
  • extracellular substances which provide the cell with materials for building protoplasm and for energy generation
A

Nutrients

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4
Q
  • any nutrient material for growth and cultivation of microorganisms in the laboratory
A

Culture Medium

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5
Q

Uses of culture medium

A
  • for growth and maintenance of microbial cultures
  • to favor the production of particular compounds
  • to study microbial action on some constituents of the medium
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6
Q

types of culture media according to physical state

A

Liquid (Broth) – no solidifying agent
Semi-solid – 0.1 - 0.5% solidifying agent
Solid – 1.5 – 2.0% solidifying agent

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7
Q

solidifying agent used

A

agar or gelatin

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8
Q

types of culture media according to chemical composition

A

synthetic, complex, dehydrated, and compounded

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9
Q

all components are chemically defined

A

Synthetic

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10
Q

not all components are chemically defined
examples are:
potato infusion (plant origin)
beef extract (animal origin)
yeast extract (microbial origin)

A

Complex

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11
Q

types of culture media according to function, purpose, or application

A

General Purpose, Differential , Selective, Enrichment, Assay

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12
Q

all the components are in one media bottle

A

dehydrated

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13
Q

from separated bottles then combined into one

A

compounded

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14
Q
  • can support most or almost all types of species
    e.g. Nutrient Agar (NA) - for bacteria, Potato Dextrose Agar (PDA) - for yeast/mold
A

General Purpose

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15
Q
  • distinguishes one type of bacteria from another
  • with special reagents like pH indicators or dyes
    e.g. Eosin Methylene Blue Agar (EMBA) - kills gram positive bacteria
A

Differential

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16
Q
  • allows the growth of a specific type of microorganism only
  • with selective agents (ex. salts, dyes, antibiotics, etc.)
    e.g. Bacillus Cereus Agar (BCA)
A

Selective

17
Q
  • used to increase the number of microorganisms with unusual physiological characteristics
  • with special nutrients (ex. blood)
    e.g. Blood Agar
A

Enrichment

18
Q
  • used to determine qualitative/ quantitative production of such a compound by an organism
  • of prescribed composition used for assay of vitamins, amino acids and antibiotics
A

Assay

19
Q

types of isolation techniques

A

Plating, Enrichment, Serial Dilution, Single-Cell Isolation Technique, Membrane Filter Technique

20
Q
  • a macroscopically visible (surface or subsurface)
    growth or cluster of microorganisms on a solid medium
A

Colony

21
Q

types of plating

A

streak, spread-plate, pour-plate

22
Q
  • isolation of specific types of microorganisms by a
    combination of nutrient and physical conditions
  • used for the isolation of unusual physiological types of
    microorganisms which are present in small numbers and
    which grow slowly
A

Enrichment Culture

23
Q
  • used if the desired microorganism is present at a higher level than any other microorganism
A

Serial Dilution

24
Q
  • uses a micropipette or a microprobe to physically pick a
    single cell and transfer it on an agar medium
A

Single-Cell Isolation Technique

25
Q
  • for samples with low population
  • uses a sterile membrane filter having a pore size that retains microorganism
A

Membrane Filter Technique

26
Q

Steps in Preparing Pure Cultures

A
  • Isolation
  • Transfer desired colony to a slant or stab
  • Verify the purity
    • microscope
    • restreak on agar medium
    • physiological and biochemical test
  • Make stock cultures
27
Q

Culture Preservation Methods

A

Periodic transfer to fresh media
Overlaying cultures with mineral oil
Freeze-drying (lyophilization)
Freezing with liquid nitrogen
Drying

28
Q

considerations for Periodic transfer to fresh media

A
  • time interval of transfers
  • proper medium
  • proper storage temperature
29
Q

aim of Overlaying cultures with mineral oil

A

limit the availability of O2 to reduce metabolic rate

30
Q

Advantages of Overlaying cultures with mineral oil

A
  • Simple
  • enables one to remove some growth under the oil and
    inoculate it in a fresh medium and still preserve the initial
    culture
31
Q

disadvantages of Overlaying cultures with mineral oil

A
  • viability of microorganisms varies with species
32
Q

rapid drying in frozen state

A

Freeze-drying (lyophilization)

33
Q

Advantages of Freeze-drying (lyophilization)

A
  • long-term survival
  • less opportunity for changes in the characteristics of culture
  • small storage containers
34
Q

Considerations of Freezing with liquid nitrogen

A

cryoprotective agent (glycerol)
liquid-nitrogen refs

35
Q

Samples are grown on sterile paper disk saturated with nutrient, then the disks are allowed to air dry and stored aseptically drying temperature = 45oC

A

Drying

36
Q

Limitation of Drying

A

for spore- and cyst-formers

37
Q

steps in drying

A
  • Drops of bacterial suspension in gelatin are placed on sterile plastic petri plates and dried off over phosphorus pentoxide under vacuum
  • Bacteria in small ampoules are dried from liquid state using vacuum pump, desiccant, and water bath
  • Organisms are dried over calcium chloride in vacuum and stored in the ref
38
Q
  • organizations which maintain authentic pure cultures of
    microorganisms
  • provide ‘type’ strains to microbiologists throughout the
    world
A

Culture Collections

39
Q

examples of Culture Collections

A

American Type Culture Collection (ATCC) in (Maryland)
National Collection of Type Cultures (NCTC) in (London)
Japan Collection of Microorganisms
Philippine National Collection of Microorganisms

mcb 11 lec (6 decks)

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