Lecture 16-17 Culture media, Cultivation techniques, & Types of cultures

Question 1

Two broad classes of culture media

Answer 1

chemically defined and complex

Question 2

Chemically defined

Answer 2

exact composition of pure chemicals used to formulate medium is known

Question 3

Used for well characterized isolates in lab studies

Answer 3

chemically defined

Question 4

Complex media (“rich” media)

Answer 4

exact chemical composition is poorly defined

Question 5

Used as a non-specific medium for growing many organisms

Answer 5

rich media

Question 6

Often naturally sourced components

Answer 6

rich media

Question 7

Selective media

Answer 7

inhibits growth of unwanted organisms, supports growth of desired organisms

Question 8

The dye that inhibits growth of Gram-positives and selects for the isolation of Gram-negatives

Answer 8

Brilliant Green (BG) agar

Question 9

Enriched media

Answer 9

contains growth factors, vitamins, and other essential nutrients to promote the growth of fastidious organisms

Question 10

Fastidious organisms

Answer 10

organisms that cannot make certain nutrients and require them to be added to their medium

Question 11

Commonly used to supply nutrients in various mediums

Answer 11

blood, serum, egg yolk

Question 12

Used to grow a wide range of pathogens, particularly those that are more difficult to grow

Answer 12

enriched media

Question 13

Differential media

Answer 13

contains compounds that allow groups of microorganisms to be visually distinguished by the appearance of the colony or the surrounding media

Question 14

What basis does differential media use to show visual differences?

Answer 14

biochemical differences

Question 15

Alpha hemolysis

Answer 15

indistinct zone of partial destruction

Question 16

Beta hemolysis

Answer 16

clear, colorless zone appears

Question 17

Gamme hemolysis

Answer 17

no apparent hemolytic activity or discoloration

Question 18

Examples of selective AND differential media

Answer 18

MacConkey Agar & Mannitol Salt Agar

Question 19

MacConkey Agar

Answer 19

inhibit Gram-positives (w/ bile salts and crystal violet) and produces a color change (w/ lactose fermenters)

Question 20

Mannitol Salt Agar

Answer 20

mannitol fermentation and phenol red for differentiation, high salt selects of S. aureus (only super hardy and high salt loving will grow)

Question 21

Colony

Answer 21

a visible mass of microbial cells arising from one cell or from a group of the same microbes

Question 22

Batch cultures

Answer 22

closed system, nutrients not renewed, exponential growth limited to a few generations

Question 23

Continuous (chemosat) cultures

Answer 23

bacterial cultures maintained in a state of exponential growth over long periods of time

Question 24

Culturing technique that allows for bacterial population at a constant density

Answer 24

continuous cultures

Question 25

What continuous culturing relieves

Answer 25

nutrient insufficiency, accumulation of waste products, and accumulation of cells

Question 26

Steps to making an aerobic culture

Answer 26

1) make culture media
2) sterilize medium
3) inoculate liquid or steak plate
4) incubate in aerobic environment until culture grows

Question 27

Used for anaerobic culturing when microbe can be mildly exposed to H2O

Answer 27

GasPak Jar or Anaerobic GasPak container

Question 28

Used for anaerobic culturing when microbe CANNOT be exposed to H2O

Answer 28

Anaerobic chamber/glove box; very delicate

Question 29

Contains only one species or strain

Answer 29

pure culture

Question 30

Colony

Answer 30

a population of cells arising from a single cell or spore or from a group of attached cells

Question 31

Another name for a colony

Answer 31

colony-forming unit (CFU)

Question 32

Method used to isolate pure cultures

Answer 32

streak plate method

Question 33

Describe the streak plate method

Answer 33

small amount of inoculum is picked up on a sterile inoculating loop, drawn repeatedly across the surface of the plate

Question 34

Biofilms

Answer 34

microbial communities

Question 35

Where do you find biofilms?

Answer 35

in slime or hydrogel environments

Question 36

Communication in biofilms

Answer 36

quorum sensing

Question 37

What quorum sensing allows for

Answer 37

allows bacteria to coordinate activity and group together into communities

Question 38

Benefits of biofilms

Answer 38

share nutrients, sheltered from harmful factors, responsible for many chronic infections and diseases

Question 39

Percentage of infections that are caused by biofilms

Answer 39

70%

Question 40

What do Biosafety Levels do (BSLs)

Answer 40

describes the condition of the lab

Question 41

BSL 1

Answer 41

for nonpathogenic microbes, PPE required, standard sterile conditions

Question 42

BSL 2

Answer 42

for pathogens not readily transmitted by aerosol/contact, same day decontamination of all biological materials

Question 43

BSL 3

Answer 43

for pathogens transferred by aerosol/contact and pose a serious health threat, water in only, protective lab clothing required, non-circulating airflow

Question 44

BSL 4

Answer 44

for readily-transmitted (highly contagious) pathogens causing fatal diseases with no preventative vaccine or cure, full-body air-supplied “space suit”, facility located in separate building