Microbial Growth

Question 1

What are nutrients?

Answer 1

supply of monomers required by cells for growth

Question 2

What is carbon as a macronutrient?

Answer 2

required by all cells, heterotrophs use organic carbon while autotrophs use CO2

Question 3

What is nitrogen as a macronutrient?

Answer 3

key elements in proteins, nucleic acids

Question 4

What is phosphorus as a macronutrient?

Answer 4

synthesis of nucleic acids and phospholipids

Question 5

What is sulfur as a macronutrient?

Answer 5

Sulfur-containing amino acids and vitamins

Question 6

What is potassium as a macronutrient?

Answer 6

required by enzymes for activity

Question 7

What is magnesium as a macronutrient?

Answer 7

stabilizes ribosomes, membranes, and nucleic acids

Question 8

What is calcium as a macronutrient?

Answer 8

required by some microbes

Question 9

What is iron as a macronutrient?

Answer 9

key component of cytochromes and FeS proteins involved in electron transport

Question 10

What are growth factors?

Answer 10

organic compounds required in small amounts by certain organisms ex: vitamins

Question 11

What is the difference between defined and complex media?

Answer 11

defined has precise chemical composition known
complex has undefined substances like yeast extracts

Question 12

What is enriched media?

Answer 12

contains complex media plus additional nutrients

Question 13

What is differential media and examples?

Answer 13

allows multiple types of bacteria to grow but displays visible differences in how they grow
ex: Spirit Blue Agar, Skim milk Agar

Question 14

What is selective media and examples?

Answer 14

inhibits the growth of bacteria
ex: Asparagine Agar, Phenyl Ethyl Alcohol Agar

Question 15

What are examples of selective and differential agars?

Answer 15

MacConkey Agar, Salmonella Shigella agar, Mannitol Salts Agar

Question 16

What is pure culture?

Answer 16

contains only one type of microbe

Question 17

What are examples of solid media to get pure culture?

Answer 17

potato slice, agar, gelatin

Question 18

What is the difference between streak, spread, and pour plate?

Answer 18

streak plate- streaking pattern on agar
spread plate- drop of liquid on agar spread with a glass rod
pour plate- mix bacteria with agar that is cooled to 42C

Question 19

What are ways to maintain pure culture

Answer 19

subculture-risk of mutation
refrigeration- 1 to 2 months
Freezing in media containing glycerol or DMSO
Freeze Drying

Question 20

How to bacteria grow?

Answer 20

divide into 2 cells by binary fission

Question 21

What are ways to count cells?

Answer 21

direct cell counting- measured microscopically
Coulter counter: electronically scans a fluid as it passes through a tiny pipette
Flow cytometer- measures cell size and differentiate between live and dead cells

Question 22

How can spectrophotometry be able to count cells?

Answer 22

through turbidity, measured through an optical density (OD reading)

Question 23

What are issues with direct counting?

Answer 23

even with a hemocytometer, takes too long

Question 24

For a viable count, which techniques are best?

Answer 24

Spread plate and pour plate (heat sensitive organisms die)

Question 25

What is the most probable number method?

Answer 25

statistical method for measuring bacteria in a liquid where bacteria can't grow on agar

Question 26

What is a batch culture?

Answer 26

a closed-system microbial culture of fixed volume

Question 27

What are the four phases of bacterial growth

Answer 27

lag, exponential, stationary, death phase

Question 28

Which stage are microbes more vulnerable to antimicrobial agents and heat?

Answer 28

exponential growth phase

Question 29

Which stage are infections more like to spread?

Answer 29

early and middle stages

Question 30

What is continuous culture?

Answer 30

an open system microbial culture of fixed volume

Question 31

What is a chemostat?

Answer 31

used in continuous culture

Question 32

What is cardinal temperatures?

Answer 32

range of temps for the growth of a given microbial species

Question 33

What are the ranges and examples of different temp ranges

Answer 33

Psychrophile- Polaromonas vacuolata Mesophile- E. Coli Thermophile- Bacilus stearothermophilus Hyperthermophile- Thermococcus celer

Question 34

What is the difference between stenothermal and eurythermal?

Answer 34

stenothermal grows in a narrow temperature range eurythermal grows in a wide temperature range

Question 35

What is osmotolerant and an example?

Answer 35

tolerates high osmotic pressure- Xeromyces sp.

Question 36

What is osmophilic and an example?

Answer 36

loves high osmotic pressure- Saccharomyces sp.

Question 37

What is halotolerant and an example?

Answer 37

doesn't need high salt concentrations- stapylococcus aureus

Question 38

What is halophilic and an exmaple?

Answer 38

needs high salt concentration- Vibrio sp.

Question 39

What is an example of an acidophile and alkaliphile?

Answer 39

acidophile- thiobacillus sp. alkaliphiles- Natonomonas sp.

Question 40

List the 5 types of oxygen cell growth

Answer 40

anaerobic- clostridium facultative- Staph microaerophilic- strep aerobic- bacillus aerotolerant- Lacrobacillus acidophillus

Question 41

What are other types of oxygen?

Answer 41

singlet oxygen: O2 Peroxide: H2O2 Superoxide: O2- Hydroxyl radical: OH*

Question 42

What is catalase?

Answer 42

2H2O2 to two water molecules and O2

Question 43

What is Peroxidase?

Answer 43

H2O2 + NADH to 2 H2O and NAD

Question 44

What is superoxide dismutase?

Answer 44

2O2- and 2H to 2 H202 and oxygen

Question 45

What is superoxide reductase?

Answer 45

O2- and cyt cred to H2O2 and cyt cox

Question 46

What are capnophiles?

Answer 46

organisms that grow best at a higher CO2 tension than is normally present in the atmosphere

Question 47

What are examples of capnophiles?

Answer 47

Neisseria, brucella, Strep.

Question 48

What are barophlies?

Answer 48

exists under extremes amount of pressure