Bacteria Nutrition, Growth, Physiology, and Metabolism

Question 1

What are the general macronutrient requirements? Micro?

Answer 1

water, carbon, oxygen, hydrogen, sulfur, phosphorus; iron and others

Question 2

What is the category of bacteria that chelate iron?

Answer 2

siderophores; possible drug target

Question 3

What is an obligate aerobe?

Answer 3

require O2 to grow, used as the terminal acceptor, undergo respiration

Question 4

What is a microaerophiles?

Answer 4

aerobes but grow best with less oxygen than in the air, O2 used as terminal acceptor, use respiration

Question 5

What is an obligate anaerobe?

Answer 5

unable to synthesize an oxygen-linked respiratory chain, don’t use O2 as terminal acceptor instead use organic compounds, utilize fermentation

Question 6

What is an aerotolerant anaerobe?

Answer 6

oxygen indifferent, can grow in presence of O2 but use organic compounds as final acceptor, fermentation

Question 7

What is a facultative anaerobe?

Answer 7

can grow in presence or absence of O2, will use it as final electron acceptor if its available (respiration) but will use organic compounds if its not available (fermentation)

Question 8

What is a psychrophile? Examples.

Answer 8

grows at fridge temps (0-30C); listeria

Question 9

What is a mesophile? Examples of some that prefer a little colder than human body temp?

Answer 9

grows at 10-45 C, human pathogen, most other bacteria; mycobacterium leprae (31), sporothrix schemkii (25), and rhinovirus (33)

Question 10

What is a thermophile?

Answer 10

grows at 25-100C, hot springs bacteria

Question 11

What is the optimal pH range for most bacteria?

Answer 11

6.5 - 7.5`

Question 12

What is a halophile? Examples.

Answer 12

grow in hypertonic or high salt (sugar) concentration, Staph aureus and enterococcus are both facultative halophiles

Question 13

What is generation time?

Answer 13

time required for population to double

Question 14

What are the phases of growth?

Answer 14

lag, log, stationary, and death

Question 15

What are the features of log phase of growth?

Answer 15

constant, min generation and max rate of reproduction, most AB susceptible, quorum sensing in late log

Question 16

What are the features of lag phase of growth?

Answer 16

active metabolism, no division, inducible enzymes due to nutrients and constitutive enzymes- required an always present

Question 17

What are the features of stationary phase?

Answer 17

nutrient depletion, waste accumulation, decrease in rate of cell division (decrease metabolic rate)

Question 18

What are the features of death phase?

Answer 18

increase in death rate, autolysis

Question 19

What is quorum sensing?

Answer 19

cell density regulated gene expression, could be a toxin or sporulation, cell to cell communication, essential for virulence of most pathogens studied

Question 20

What are persistor cells?

Answer 20

metabolically dormant, responsible for : increased antibiotic resistance and chronic recurrent infections

Question 21

In anaerobic respiration what metabolic systems/enzymes are used?

Answer 21

up to some of the cytochromes of the ETC to transfer electrons to an alternate acceptor (some, aerobes, facultative anaerobes and anaerobes)

Question 22

In anaerobic respiration what is sometimes utilized for the final electron receptor? Why is this important clinically?

Answer 22

nitrate to nitrite, can test in urine for UTI, (some aerobes)

Question 23

What is a B enzyme?

Answer 23

a virulence factor, breaks complex molecules (polysaccharides, fats and proteins) into simple form