Microbial Growth Flashcards
What is the temp range for mesophiles?
Between 25C and 45C.
What is the temp range for psychrophiles?
-5 C to 15C
What is the optimum temp for growth in the human body?
Between 35C and 40C
What is the temp range for thermophiles?
Between 45C and 70C.
Obligate aerobes have an absolute requirement for what?
Oxygen
What do obligate aerobes use oxygen for?
To generate energy via aerobic respiration
What cannot happen if oxygen is present with obligate anaerobes?
Cannot multiply, often killed by traces of oxygen because of toxic derivatives.
Do facultative anaerobes grow better or worse with oxygen present?
Better. Because aerobic respiration yields the most ATP
*but can also grow without it.
How much oxygen do microaerophiles require for aerobic respiration?
Small amounts (2-10%) Higher concentrations are inhibitory.
Describe aerotolerant anaerobes
Indifferent to oxygen.
Can grow in O2 presence but do not use it to transform energy.
What are some toxic derivatives of oxygen?
Superoxide
Hydrogen peroxide
OH*
How is hydrogen peroxide toxic?
It is an oxidizing agent
Does not damage the cell as much as superoxide
Which toxic derivative of oxygen is very damaging but transient in cells?
OH*
What converts O2- to H2O2 and O2?
Superoxide dismutase
What converts H2O2 to H2O and O2?
Catalase
What is the typical pH maintained in the cell?
Typically 7
What is the pH range for neutrophiles?
Live and multiply from 5-8
What is the pH range for acidophiles?
Below 5.5
When might you find neutrophiles?
In gut bacteria. They have unique mechanism to change pH.
What is the pH range for alkalophiles
Above 8.5
What do all microbes require for growth?
Water
How can microbes survive and multiply in very high salt concentrations?
By increasing the solute concentration inside the cell.
What are osmotolerant bacteria?
Those tolerant of high salt environment. (Up to 10%)
What are halophiles?
Require high levels of salt to live and multiply (more than 10%)
What two ways can microbes increase solute concentration inside the cell?
- pump ions (most often K+) from outside to inside
- synthesize small organic compounds that have no effect on normal cellular activity (often proline)
