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M1 Micro Bacteriology Quiz 1 > 04_Bacterial Metabolism > Flashcards

Flashcards in 04_Bacterial Metabolism Deck (26)
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1

These cards are complete and contain info from lecture and notes.

These cards are complete and contain info from lecture and notes.

2

Know: substrate level phosphorylation, oxidative phosphorylation, aerobic and anaerobic

Know: substrate level phosphorylation, oxidative phosphorylation, aerobic and anaerobic

3

What is the glyoxylate shunt

• shunt within the krebs cycle that uses acetylCoA to shunt isocitrate to malate
• This is used when acetylCoA is generated from acetate, which occurs when bacteria grow on a fatty medium rather than a sugar medium

4

Are there examples when the electron transport chain is still used anaerobically?

• Some bacteria can us NO3- instead of O2 in the ETC.
• NO3 is reduced to N2.

5

Note: in the ETC, H are pumped in the space between the inner membrane and the cell wall. H then use the ATP synthase (like in mammals). H also use anti-ports that expel unwanted substances from the bacteria (like antibiotics)

Note: in the ETC, H are pumped in the space between the inner membrane and the cell wall. H then use the ATP synthase (like in mammals). H also use anti-ports that expel unwanted substances from the bacteria (like antibiotics)

6

There is a basic chart comparing respiration vs fermentation on page C-3. The info is basic.

There is a basic chart comparing respiration vs fermentation on page C-3. The info is basic.

7

What are the features of lactic acid production?
What are examples of bacteria that use this pathway?

• reduces pH
• used in pickles, sauerkrauts, and cheeses
• Lactobacilli (edible ferments)
• Streptococcus pyogenes (strep throat)

8

What is the relevance to pre-puberty, women with menses, and post-menopausal women?

• the reduced pH protects against Candida albicans
• Pre-puberty and post-menopausal women do not have lactobacilli and the pH of their vaginas are neutral

9

Explain Butyric Acid Fermentations (also butanol-acetone fermentations)
What is the classic bacteria?
What are the products?
What is a diagnostic feature?

• Clostridia
• Forms butyric acid, acetic acid, CO2, H2, and small amounts of alcohols
• If H2 or butyric acid is present (air bubbles in tissues) ==> diagnosis Clostridia
• Butyric acid has a distinctly unpleasant odor (ex: gangrene)

10

When is Clostridium protective?

• can protect against hemorrhagic E. coli strains (hemorrhagic colitis)

11

Explain propionic acid fermentation.
What bacteria?
What is the signature feature of propionic acid fermentation?
What is a common food product that uses this fermentation?
What is a clinically relevant event that uses this fermentation (think embarrassed teenager)?

• propionic acid bacteria: corynebacteria: propionibacterium and bifidobacterium.
• Signature: ferment lactate ==> acetic acid, CO2, and propionic acid
• Used in swiss cheese (CO2 produces bubbles)
• Propionibacteriium acnes are involved with acne

12

Explain mixed acid fermentations by enteric microbes.
What are some products?
How is this phenomenon used clinically?

• microbes in the intestines use many distinct and overlapping pathways to ferment due to competition (lots of bacteria, very little space)
• succinate, lactate, ethanol, formate ==> H2 and CO2, acetate, acetoin, butanediol
o see details on page C-4 bottom. However, details are not needed currently
• products of a bacteria fermentation may be diagnostic
o example:
• shingella produces formic acid, not H2
• Salmonella produces formic acid and H2

13

Explain when 2,3 butanediol and acetoin are used clinically?

• some bacteria produce butanediol and its intermediate acetoin.
• These are neutral pH (low acid)
• May be used to distinguish…
o non-fecal enteric bacteria (butanediol formers, such as Klebsiella and Enterobacter)
o fecal enteric bacteria (mixed fermenters, such as E. coli, Salmonella, and Shigella

14

Explain ethanol fermentation.
What microorganisms use ethanol fermentation?
What are the products?

• performed by yeast: Saccharomyces cerevisiae
• Performed by fungus: Candida albicans
• Pyruvate ==> CO2 and ethanol
• CO2 gas provides mild acid, however, in alkaline tissues CO2 becomes carbonate

15

What is the Stickland Reaction?
What bacteria uses the Stickland Reaction?
What are the substrates?

• clostridia
• pairs of amino acids alternatively act as the electron donor and acceptor
o Alanine (donor)
o Glycine (acceptor)
• Occurs in putrefying wounds.

16

What determines a microbes relationship with oxygen?

• respiration vs fermentation
• ability to detoxify oxygen radicals

17

Explain Obligate aerobes.

• respiration throught the electron transport chain
• no enzymes for fermentation

18

Explain how Pseudomonas aeruginosa are considered obligate aerobes.

• cannot ferment sugars
• can respire in the absence of oxygen using nitrate NO3-
• Note: respiration in the absence of oxygen is called anaerobic respiration

19

What is anaerobic respiration?

• respiration in the absence of oxygen

20

Explain facultative anaerobes.

• grow with or without oxygen
• Have both respiration and fermentation enzymes
• Note: more ATP comes from respiration
• Ex: E coli and Staphylococcus

21

Explain Obligate anaerobes.
What respiration byproducts are harmful to anaerobes?
Where are these found in the body?

• no respiration, only fermentation
• require reducing conditions to grow, and cannot grow in the presence of O2
• Produce H2O2 and superoxides (toxic to the bacteria) due to subsequent ROS
• Lack Catalase: a heme containing enzyme that breaks down H2O2
• Lack Superoxide Dismutase: breaks down superoxide
• Example: Bacteroides Fragilis
• Found deep in gut, abscesses, and deep puncture wounds

22

What is Catalase?
What is Superoxide Dismutase?

• Catalase, a hemoprotein enzyme present in most aerobes which decomposes H2O2.
o 2 H2O2 → H2O + O2 [gas]
• Superoxide dismutase breaks down superoxide, a highly reactive free radical reactive form of oxygen (O2-), formed by flavoenzymes.
o 2O2- +2H+ →H2O2+O2

23

Explain Aerotolerant anaerobes.

• do not have respiration capability, but can break down Oxygen radicals and are therefore indifferent to Oxygen
• Lactic acid species: Lactobacillus and Streptococcus
• Some Clostridium

24

Explain Microaerophiles.

• prefers 5% oxygen environments
• example: Campylobacter jejuni grows in the intestines where there is modest O2

25

Where do anaerobes exist within the host?

• mouth, urinary tract, deep in the gut, abscesses, or deep punctures
• can grow in areas with other aerobes that use up all the oxygen or if strong reducing agents (cysteine or thioglycollic acid)

26

Some bacteria can digest glucose, others lactose, others other substrates. This can be diagnostic

Some bacteria can digest glucose, others lactose, others other substrates. This can be diagnostic