Microbial Nutrition and growth

Question 2

Syntropy

Answer 2

Bacteria need metabolites or results (ie pH change due to H+) from others to live.

Question 3

Saprophytes

Answer 3

Fungi which produce many degrading enzymes

Question 4

Lithotrophy

Answer 4

use of inorganic substances as sources of energy

Question 5

Photoheterotrophy

Answer 5

use of organic compounds as a carbon source during bacterial photosynthesis

Question 6

Give some examples of terminal electron acceptors

Answer 6

Aerobic: O2 to H2O; Anaerobic–Nitrate reduction: NO3 to NO2/N2; Sulfur reduction SO4 to S or H2S; Organic: Fumarate to succinate; CO2 to methane

Question 7

Explain dead zones

Answer 7

Chemical run off from fields, metabolized by blue-green algae (bacteria) blooms, block light and lower O2 below, other bacteria consume remaining O2, animals die, anaerobic bacteria leftover

Question 8

Two categories of nutrients

Answer 8

Supply energy and supply carbon (Often overlap)

Question 9

Define nutrients

Answer 9

elements and specific combinations of elements (chemicals) that specific organisms require for growth and repair

Question 10

What are the 4 nutrition types of bacteria?

Answer 10

Photoautotrophs, chemoautotrophs, photoheterotrophs, chemotereotrophs

Question 11

Photoheterotrophs

Answer 11

Light energy, Organic compounds for carbon

Question 12

Photoautotrophs

Answer 12

Light energy, CO2 for carbon

Question 13

chemoautotrophs

Answer 13

Chemical compounds for energy, CO2 for carbon

Question 14

chemotereotrophs

Answer 14

Chemical compounds for energy, organic compounds for carbon (aerobic/anaerobic respiration, fermentation)

Question 15

Obligate Aerobe

Answer 15

Must have O2 for aerobic respiration

Question 16

Microaerophile

Answer 16

Don’t like too much oxygen, but they need some.

Question 17

Obligate Anaerobe

Answer 17

O2 is toxic to them

Question 18

Facultative Anaerobe

Answer 18

Ex E.coli; uses O2 when available, but not needed

Question 19

Aerotolerant Anaerobe

Answer 19

Don’t mind oxygen, but don’t need it

Question 20

Thioglycollate broth

Answer 20

gets rid of oxygen so you can make a deoxygenated solution

Question 21

Why O2 toxic to some and not others?

Answer 21

Reactive oxygen species; reduce or oxidize inside a cell = uncontrolled reaction; Some bacteria have enzymes to remove the reactive species

Question 22

How can cells get rid of reactive O2 species?

Answer 22

Superoxide dismutase, then either catalase or peroxidase

Question 23

Effects of temperature

Answer 23

Denature enzymes; change flexibility of membrane; cold decreases enzyme activity and diffusion rates

Question 24

Category of bacteria w.r.t. temp are common human pathogens

Answer 24

Mesophiles (about 20-40˚C)

Question 25

Psychrophiles

Answer 25

Like low temperatures (-5-20˚C)

Question 26

Environmental effects of growth

Answer 26

temperature, pH, O2 levels, pressure, osmotic pressure

Question 27

What effect can pH produce (multiple bacteria involved)

Answer 27

One bacteria might bring the pH down (via wastes etc) then stop growing, then the next one can start growing at that pH, then the next one etc.

Question 28

Obligate halophiles

Answer 28

Grow under strong osmotic pressure

Question 29

What relationships exist b/w bacteria?

Answer 29

Antagonistic, symbiotic, synergistic, predatorial

Question 30

Synergistic vs symbiotic

Answer 30

Synergistic: two types can’t exist without the other present; Symbiotic: can be both benefitting, or only one benefitting

Question 31

Quorum sensing

Answer 31

Bacteria always secreting signals; when there is enough bacteria cells present, they start producing certain virulence factor genes, which allow for biofilms and infectious disease

Question 32

Inoculum

Answer 32

A little bit of bacteria that are contained in a loop introduced to a medium

Question 33

Describe the types of plates used for isolation

Answer 33

Streak plate (classic); pour plate: Sequential inoculations into 9 mL broth (dilute), each time put 1 mL of it onto a plate and add 9mL warm agar; spread plate: serial dilutions spread with hockey stick

Question 34

Defined media

Answer 34

specific media for a very picky bacteria

Question 35

Complex media

Answer 35

Contains many different growth factors

Question 36

Differential media

Answer 36

Related to selective media; identifies based on fermentation etc. Ex. MacConkey agar is selective and differential

Question 37

Generation time

Answer 37

The time required for a bacterial cell to grow and divide (double in number

Question 38

Bacterial growth curve phases (batch culture)

Answer 38

Lag phase: no apparent growth, adjusting (genes to degrade turned on slowly, then enzymes released and slowly start growing); log phase: exponential; Stationary phase: toxic byproducts and limited nutrients; Death phase: more death than growth

Question 39

When are bacteria more sensitive to antibiotics?

Answer 39

In the log phase: lots of metabolism and cell building which we can disturb.

Question 40

Chemoreactor

Answer 40

Machine that maintains optimum bacterial growth by replacing nutrients and O2, and removing toxic byproducts and extra cells and product (ie target gene)