Bacterial Nutrition, Metabolism, & Growth

Question 0

Heterotrophic metabolism

Answer 0

The sources of energy & carbon are organic carbon sources (carbohydrates, protein, lipid).

–> most pathogenic bacteria are heterotrophic.

2 forms: respiration & fermentation

Question 1

Autotrophic metabolism

Answer 1

Fixes CO2

• cellular energy is obtained from oxidation/reduction of inorganic ions (chemoautotroph)
• or harvesting light energy (photoautotroph)

Question 2

Halophile

Answer 2

Salt loving bacteria

Ex:
Vibrio cholera

Question 3

Low or elevated levels of ______ can serve as triggers fm for pathogens.

Answer 3

Iron

Low levels of Fe induces Corynebacrerium diphtheriae to produce diphtheria toxin.

During an infection the human body sequesters Fe & excretes the excess to keep it away from bacteria.

Question 4

Mesophiles

Answer 4

Growth occurs between 20-55 degrees C

Most grow best at body temp (35-36C)

Question 5

Thermophiles

Answer 5

Obligate or facultative

Grow at temps greater than 55C

Question 6

Psychrophiles & Cryophiles

Answer 6

Grow at temps <20C

Question 7

Is refrigeration a acceptable method of maintaining or obtaining sterile conditions?

Answer 7

NO!!!!

Question 8

How can Aerobes & facultative aerobes can grow in the presence of O2?

Answer 8

b/c produce enzymes which by detoxify superoxide radicals & hydrogen peroxide.

–> Superoxide dismutase (SOD) detoxifies O2

Question 9

Obligate aerobes

Answer 9

Require the presence of atmospheric O2 for growth.

–> mycobacterium tuberculosis.

Question 10

Microaerophilc organisms

Answer 10

Require the presence of some O2 but NOT at atmospheric levels (reduced O2)

E.g. Campylobacter

Question 11

Facultative anaerobes

Answer 11

Can grow in the presence or absence of O2.

Many pathogens are facultative anaerobes!!

Ex: enteric bacteria

Question 12

Aerotolerant anaerobes

Answer 12

Can survive in the presence of O2

Ex: lactobacillus

Question 13

Obligate anaerobes

Answer 13

Killed by the presence of O2.

Ex: Clostridium, bacteroides, & others.

(Lack in the enzymes superoxide dismutase & catalase)

Question 14

Respiration

Answer 14

An enzymatic process but it is a unique enzymatic process must occur in a membrane vesicle or sack.

Provides energy via proton motive force for ATP synthesis (prod) during the conversion (recycling) of NADH2 to NAD

Question 15

Catalase

Answer 15

Detoxifies hydrogen peroxide (H2O2) produced by superoxide dismutase

Question 16

Superoxide dismutase

Answer 16

Detoxifies O2 (superoxide anion)

Question 17

Aerobic respiration

Answer 17

Oxidative phosphorylation
O2 is the terminal electron acceptor –> reduced by the electron transport system.

Common in pathogenic microorganisms & humans

Question 18

Anaerobic respiration

Answer 18

Inorganic compounds (nitrite, sulfate, etc.) serve as terminal electron acceptors.

Any organism w/ the nitrate reductase pathway is able to grow in the absence of oxygen in the presence of nitrate, which is present in inflam processes.

Ex: pseudomonas aeruginosa

Question 19

Fermentation

Answer 19

Results in the incomplete oxidation of a carbon substrate. Fermentation is less efficient process than respiration.
Fermentation consists of catabolic pathways where organic compounds serve as electron donor is an electronic accepters.

substrates are partially oxidized, generating end products which:
1. Are carbon compounds
2. Serve as the electron acceptor (accept e- & H+)
3. Are released from the cell.
Pyruvate–> ETOH+CO2

Question 20

Dental carries

Answer 20

Caused by streptococcus mutans which produce lactic acid (via fermentation)

Question 21

Acidification of skin & vagina:

Answer 21

By lactobacillus sp. which prod lactic acid

& Propionibacterium acnes which prod Propionic acid via fermentation

Question 22

Abscesses are ________ & ________ d/t fermentative metabolism of bacteria in the abscess

Answer 22

Acidic & anaerobic

Question 23

How are abscesses able to thrive?

Answer 23

Many antibiotics are not effective at low pHs. Acidic

Low pH kills surrounding viable human cells including phagocytes.

Question 24

In fermentation, organisms do not use NAD or NADP as e- and H+ carrier, but rather _________ is used

Answer 24

Ferredoxin

Question 25

What is required to recycle reduced ferredoxin to the oxidized form?

Answer 25

Hydrogen lyase

Question 26

Clostridium perfringens

Answer 26

Can cause gas gangrene (myonecrosis)

–> produces hydrogen gas which is insoluble in tissues. It tracks along Fascial planes separating muscle tissues (thus gains bacteria access to fresh tissue), collapses blood vessels, impedes perfusion, all of which help to create anaerobic conditions.

Question 27

Dextrans

Answer 27

Synthesized from sucrose by Streptococcus mutans.

In dental plaque

Can be H2O soluble –> noncaryogenic plaque= fructosyltransferase.

Cariogenic –> glucosyltransferase

Question 28

Proteus spp. Causes what type of infection?

Answer 28

UTIs

Produces ammonia –> increases urine pH
–> more alkaline–> calculi (kidney stones)

Question 29

Helicobacter pylori

Answer 29

Can cause stomach ulcers or CA.

Produces ammonia –> raises the microenvironment pH

Question 30

Transpeptidase or penicillin binding protein play a role in synthesis of ____________

Answer 30

Peptidoglycan

Selected for by many antibiotics.