ILQ 4 - Ex 10-12

Minimum Growth Temperature

Lowest temperature at which a specific organism will grow and reproduce

Optimum Growth Temperature

Temperature at which a specific organism exhibits maximum growth and reproduction

Maximum Growth Temperature

Highest temperature at which a specific organism will grow and reproduce

Psychrophile

Grows between -10°C and 20°C

Mesophile

Grows between 20°C and 45°C

Psychrotolerant

Grows below 10°C but can also grow in the mesophile range

Thermophile

Grows between 45°C and 80°C

Hyperthermophile

Grows between 80°C and 110°C

Pseudomonas fluorescens

Psychrophile control organism

Serratia marcescens

Psychrotolerant control organism

Escherichia coli

Mesophile control organism

Bacillus stearothermophilus

Thermophile control organism

Obligate Aerobe

Requires oxygen to live; grows only at the top of a BHI deep tube

Microaerophile

Requires small amounts of oxygen; grows as a thin band just below the top of a BHI deep tube

Facultative Anaerobe

Uses oxygen if available but can grow without it; heavy growth at top and light growth throughout tube

Aerotolerant Anaerobe

Does not use oxygen but tolerates it; even growth throughout the tube + can detox enzymes

Obligate Anaerobe

Oxygen is toxic; grows only at the bottom of the tube

Why do obligate aerobes grow at the top of a BHI deep tube?

They require oxygen as the final electron acceptor for respiration

Why do microaerophiles grow just below the top of a BHI deep tube?

They require reduced oxygen levels because atmospheric oxygen (21%) is toxic

Why do facultative anaerobes grow heavily at the top but throughout the tube?

They produce more ATP with aerobic respiration but switch to fermentation or anaerobic respiration when oxygen is absent

Why do aerotolerant anaerobes grow evenly throughout a BHI deep tube?

They do not use oxygen but tolerate it because they possess detoxifying enzymes

Why do obligate anaerobes grow only at the bottom of a BHI deep tube?

Oxygen is toxic to them

Top of BHI deep tube

High oxygen concentration

Middle of BHI deep tube

Low oxygen concentration

Bottom of BHI deep tube

No oxygen (anoxic)

Mycobacterium smegmatis

Obligate aerobe control organism

Micrococcus luteus

Obligate aerobe control organism

Bacillus megaterium

Obligate aerobe control organism

Staphylococcus xylosus

Facultative anaerobe control organism

Serratia marcescens

Facultative anaerobe control organism

Enterococcus faecalis

Aerotolerant anaerobe control organism

Clostridium sporogenes

Obligate anaerobe control organism

How does an AnaeroPack remove oxygen?

It uses chemical oxygen absorption with ascorbic acid and other oxygen-absorbing chemicals

What happens when the AnaeroPack absorbs oxygen?

It removes oxygen from the chamber and simultaneously produces carbon dioxide

Does the AnaeroPack require water?

No

Purpose of the AnaeroPack

Creates an anaerobic environment for growing obligate anaerobes