Microbial Growth

Question 1

Physical requirements for growth

Answer 1

pH
Temperature
Osmotic Pressure

Question 2

Chemical requirements for growth

Answer 2

Carbon
Nitrogen
Sulfur
Phosphorus
Oxygen
Trace elements
Organic growth factors

Question 3

3 primary groups for temperature

Answer 3

Psychrophiles (cold dudes)
Mesophiles (normal dudes)
Thermophiles (hot dudes … pause)

Question 4

Pyschotrophs

Answer 4

Grow at 0 degrees celsius
Optimum temp 20-30
Can’t grow past 40
Food spoilage of refrigerated foods

Question 5

Mesophiles

Answer 5

Optimum of 25-40
Very similar temp to us as humans (our body temp)
Live in animals
Most common spoilages and disease organisms

Question 6

Thermophiles

Answer 6

Optimum 50-60
Hyperthermophiles >80

Question 7

What pH do bacteria grow best in?

Answer 7

Between 6.5 and 7.5

Question 8

What do you use to neutralize and maintain proper pH?

Answer 8

Buffers

Question 9

What causes plasmylosis?

Answer 9

high osmotic pressure

Question 10

What is phosphorus used for?

Answer 10

DNA
RNA
ATP

Question 11

Trace elements facts

Answer 11

Usually as enzyme cofactors
Inorganic elements required in small amounts
Iron
Copper
Zinc
Molybdenum

Question 12

Microbes that require oxygen to live are called?

Answer 12

obligate aerobes

Question 13

True or false: Obligate aerobes are at a disadvantage and if so why?

Answer 13

TRUE
Oxygen is poorly soluble in water of their own environment

Question 14

Facultative anaerobns are?

Answer 14

Ability to continue growing withount oxygen
Genus: Clostridium

Question 15

Half of dry weight of a typical bacteria cell is?

Answer 15

Carbon

Question 16

Chemoheterotrophs get most of their carbon from?

Answer 16

The source of their energyW

Question 17

What’s sulfur used for ?

Answer 17

Amino Acids
Thiamine
Biotin
Most bacteria decompose protein for the sulfur source

Question 18

What are the enzymes that help deal with toxic forms of oxygen produced during cellular respiration?

Answer 18

Superoxide dismutase
Catalase
Peroxidase

Question 19

Aerotolerant Anaerobes are?

Answer 19

Fermentative
CANNOT use oxygen for growth
Tolerates oxygen
Contain superoxide dismutase

Question 20

Microaerophiles

Answer 20

Are aerobic
Require oxygen
Only grow in oxygen concentrations lower than those in air
Are sensitive to superoxide radicals and peroxides

Question 21

Where are biofilms found?

Answer 21

Digestive system
Sewage treatment systems
Can clog pipes

Question 22

Biofilms are involved in __ infections (percentage)

Answer 22

70%

Question 23

How do bacteria in biofilms communicate?

Answer 23

Quorum sensing

Question 24

Culture media definition

Answer 24

Nutrients prepared for microbial growth

Question 25

Sterile means?

Answer 25

No living microbes

Question 26

Innoculum definition

Answer 26

Introducing microbes into medium

Question 27

What is a culture?

Answer 27

Microbes growing in or on a culture medium

Question 28

What is agar used as?

Answer 28

Solidifying agent for culture media in petri dishes slants deeps

Question 29

Agar is not __ by microbes

Answer 29

Metabolized

Question 30

Agar liquifies at __ and solidifies at__

Answer 30

100 celsius 40 celsius

Question 31

What are the types of culture media?

Answer 31

Chemically defined Complex media

Question 32

Chemically defined media is?

Answer 32

Exact chemical composition is known

Question 33

Complex media is?

Answer 33

Extracts of meat, yeast, or plants chemical composition varies bach to bach

Question 34

Types of complex medias?

Answer 34

Nutrient broth Nutrient agat

Question 35

In complex media; the energy, carbon, nitrogen, and sulfur requirements of the microorganism are provided by ___?

Answer 35

Protein

Question 36

Partial digestion does what?

Answer 36

Acids or enzymes reduce proteins to peptones (shorter chain amino acids)

Question 37

What is reducing media used for?

Answer 37

Cultivation of anaerobic bacteriaW

Question 38

What chemical does reducing media have and what does it do?

Answer 38

Sodium thioglycate This combines with O2 and depletes it

Question 39

What is selective media used for?

Answer 39

Used to see one particular microorganism

Question 40

Differential media is to for?

Answer 40

Distinguishing colonies of a specific microorganism

Question 41

True or false: Differential and selective medias can be combines

Answer 41

TRUE Mannitol Salt agar Used to select for halophiles

Question 42

What's an enrichment culture?

Answer 42

Provides nutrients and environmental conditions that favor a particular microbe

Question 43

What is a pure culture?

Answer 43

Contains only one species or strain

Question 44

What is a colony?

Answer 44

Population of cells arising from a single cell or spore AKA colony forming unit

Question 45

What method is used to isolate pure cultures?

Answer 45

Streak plate method

Question 46

How do bacteria grow? (increase in number)

Answer 46

Binary fission

Question 47

Binary fission steps

Answer 47

Cell elongates and dna is replicated Cell wall and plasma membrane constrict Cross wall froms seperating the DNA Cells seperatw

Question 48

What is the generation time?

Answer 48

When number of cells in each generation is expressed as a power of 2, the exponent tells the number of generations (doublings) that have occured Time required for cell to divide

Question 49

4 basic phases of growth

Answer 49

Lag Log Stationary Death Phase

Question 50

Lag phase

Answer 50

Intense activity but no increase in population

Question 51

Log phase

Answer 51

Increase in population

Question 52

Stationary phase

Answer 52

Period of equilibrium

Question 53

Death phase

Answer 53

Population is decreasing

Question 54

What's an advantage of using the plate count method?

Answer 54

It measures the number of viable cellsW Most common used

Question 55

What's a disadvantage of plate count method?

Answer 55

It takes time , usually 24 hours

Question 56

What do platecounts assume?

Answer 56

Assume that each live bacterium grows and divides to produce a single colony However, this is not always true

Question 57

What can cause innacuracy in plate count?

Answer 57

Too many colonies present and cells overcrowd and don't develop

Question 58

What is the golden rule

Answer 58

FDA: 24-250 Scientists: 30-300

Question 59

Serial dilution does what?

Answer 59

Dilutes the original inoculum several times to ensure colony is in golden rule range

Question 60

When is most probable number method useful?

Answer 60

When microbes won't grow on solid medium When growth of bacteria in liquid differential medium is used to id microbes