Quiz 5 - Oxygen Requirements

What are two components causing oxidative stress?

1. Peroxides

2. Free oxygen radicals

Peroxides

act as oxidating agents, which can strip off electrons off of other molecules

Free oxygen radicals

1. have unpaired electrons and are highly reactive

2. tend to attack double bonds and can cause permanent damage to DNA

What are two components that protect against oxidative stress?

1. Catalase

2. Superoxide dismutase

obligate aerobe

Only aerobic growth; oxygen required

Facultative anaerobe

Both aerobic and anaerobic growth; greater growth in presence of oxygen

Obligate anaerobe

Only anaerobic growth; ceases in presence of oxygen

Aerotolerant anaerobes

Only anaerobic growth; but continues in presence of oxygen

Microaerophiles

Only aerobic growth; oxygen required in low concentrations

What four substances make up fluid thioglycollate medium?

1. Glucose

2. Cysteine

3. Thioglycollate

4. Resazurin

Thioglycollate

Lowers oxidation/reduction potential

Resazurin

O2 indicator: redox sensitive dye that turns red in presence of oxygen

What is the purpose of FTM?

Creates an oxygen gradient that differentiates aerotolerance

What happens to methylene blue in absence of O2?

It becomes colorless

How is oxygen removed from the anaerobic chamber?

By combining with hydrogen to form water

What catalyzes the anaerobic chamber reaction between oxygen and hydrogen gas?

Palladium Pallets

What does carbon dioxide promote inside the anaerobic chamber?

Promotes more rapid growth of microorganisms

Why is water added to the gas generator envelope?

To generate H2 and CO2

What is the candles jar system?

Hi CO2 levels and lower O2 levels created by burning a candle inside a jar

What type of microorganisms is the candle jar system used for?

Capnophiles (CO2 loving)