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BIOL 230 > MicroLecE2Ch6 > Flashcards

MicroLecE2Ch6 Flashcards

1
Q

What are the physical requirements for Microbial growth?

A

1) Temperature: minimum growth temp, maximum growth temp, optimal growth temp
2) pH: most bacteria grow btwn 6.5 & 7.5
3) Osmotic Pressure: salt concentration

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2
Q

Psychrophile

A

0-10 C
Found in ocean floor, polar regions
Can grow below freezing

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3
Q

Psychotroph

A

20 C

Causes food spoilage

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4
Q

Mesophile

A

37 C
Most of pathogens
Found on other living organisms

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5
Q

Thermophile

A

60 C

Found in sunlit soil

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6
Q

Hyperthermophile

A

90 C
Survives in very hot environments
Deep sea thermal vents

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7
Q

Neutrophile

A

Bacteria that prefer neutral pH

Most pathogens

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8
Q

Acidophile

A

Grow in acidic environments

Exs: molds & yeasts grow btwn pH 5-6

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9
Q

Halophile

A

Bactera that like to live in high salt environment

Exs: S. Epidermidis, S. Aureus

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10
Q

What are the chemical requirements for Microbial growth?

A

1) Carbon: structural organic molecules, energy source, used in all 4 chemical groups; from organic carbon sources or CO2
2) Nitrogen: amino acids and proteins; from ammonia, nitrogen fixation, and atmospheric nitrogen
3) Sulfur: amino acids, thiamine, biotin; get from sulfate, hydrogen sulfide
4) Phosphorus: DNA, RNA, ATP, membranes, nucleic acids; get from recycling broken down nucleic acids
5) Trace Elements: inorganic elements required in small amounts, usually as enzyme cofactors; get from the environment
6) Oxygen
7) Organic Growth Factor: organic compounds obtained from environment; vitamins, amino acids, purines, pyrimidines

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11
Q

Sterile

A

No living microbes

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12
Q

Inoculum

A

Introduction of microbes into medium

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13
Q

Culture

A

Microbes growing in and on culture medium

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14
Q

Agar

A

Complex polysaccharide from seaweed used as solidifying agent for culture media
Better than gelatin b/c stays solid at 37 C and is not broken down by microbes

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15
Q

Chemically Defined Media

A

Exact chemical composition is known

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16
Q

Complex Media

A

Pre-prepared media, most of the media used in Micro lab

Exs: nutrient broth, nutrient agar

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17
Q

Reducing Media

A

Specialized media containing thioglycollate or oxyrase that removes oxygen, typically has an oxygen gradient

18
Q

Anaerobic chamber

A

Obligate anaerobes must be grown within here where all the oxygen has been removed

19
Q

Obligate Aerobe

A

Must have presence of oxygen to grow

Growth on the surface of the thioglycollate broth

20
Q

Facultative Anaerobe

A

Can use oxygen but does not require it

Growth throughout tube with concentration on the surface of broth

21
Q

Obligate Anaerobe

A

Cannot grow in presence of oxygen

Growth at bottom of tube where there is least oxygen in the broth

22
Q

Microaerophile

A

Prefer less oxygen than aerobes; halfway btwn aerobe and anaerobe
Grows in a band in the middle of thioglycollate broth

23
Q

Capnophile

A

Requires higher level of CO2

Grows in a Candle Jar so when the candle flame goes out it raises the level of CO2 in the jar

24
Q

BSL 1

A

No special precautions

25
Q

BSL 2

A

Lab coat, gloves, eye protection

26
Q

BSL 3

A

Known pathogenic bacteria that is contagious

BSL 2 + biosafety cabinets to prevent airborned transmission

27
Q

BSL 4

A

Extremely contagious, very pathogenic microorganisms

BSL 3 + sealed negative pressure, exhaust air filtered twice, maybe govt security clearance

28
Q

Selective Media

A

Has a chemical that will inhibit growth of some bacteria but select for growth of some bacteria
Ex: salt
For ID-ing a bacteria

29
Q

Differential Media

A

Test built into the media that has a color change; makes it easy to distinguish colonies of different microbes
Ex: mannitol (sugar)
For ID-ing a bacteria
Most of the time media will be both selective and differential

30
Q

Enriched Media

A

Has a molecule in it that encourages the growth of the deried microbe, enriching for the target bacteria
For isolating a bacteria

31
Q

Colony

A

Population of cells arising from a single cell or spore or from a group of attached cells
Often called a colony-forming unit (CFU)

32
Q

Streak Plate Method

A

Used to isolate pure cultures
Every time original streak is streaked to another quadrant of the dish it is diluted until eventually the bacteria will be isolated

33
Q

Preserving Bacteria

A

1) Deep Freezing

2) Lyophilization (freeze drying)

34
Q

Binary Fission

A

1) cell elongates and DNA is replicated
2) cell wall and plasma membrane begin to constrict
3) cross-wall forms, completely separating the two DNA copies
4) cells separate

35
Q

Phases of Growth

A

1) Lag phase: bacteria sensing its environment once introduced in it, prepare for binary fission
2) Log phase: highest rate of growth, population dramatically increases, binary fission happens
3) Stationary phase: no active growth; bacteria has run out of nutrients and space
4) Death phase: bacteria die off at exponential rate; waste products have built up becoming toxic to the bacteria cells

36
Q

Direct vs. Indirect Count

A

Direct count - directly/actually counting

Indirect count - estimating

37
Q

Direct Count Methods

A

1) Serial Dilutions: several dilutions done and each one is plated; # of colonies x dilution factor
2) Plate Counts: pour plate method and spread plate method (count colonies on plates that have 25-250 colonies or 30-300 colonies)
3) Membrane Filtration (non-viable direct count)
4) Direct Microscopic count

38
Q

Indirect Count Methods

A

1) Turbidity: estimate by cloudiness using Spectrophotometer that shines light through it and measures the amount of light coming out the other side
2) Metabolic activity: measure amount of ATP and use that to estimate # of bacteria
3) Dry Weight: dehydrate a culture, weight resulting powder, estimate how much bacteria in it

39
Q

Turbidity

A

Scientific term for cloudiness

Higher the concentration of bacteria, the more turbid it is

40
Q

Generation Time

A

Time it takes for one bacteria to divide into two, or for the population to double. Bacterial growth is logarithmic

BIOL 230 (9 decks)

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