BT2: Intro to bacteriology 2 Flashcards
Define obligate aerobes.
Bacteria that always require oxygen (can’t survive without oxygen).
Define microaerophiles.
Bacteria that require oxygen at a lower level than atmospheric level.
Define facultative aerobes/anaerobes.
Bacteria that can live with or without oxygen.
Define aerotolerant anaerobes.
Bacteria that do not require oxygen to live but can survive in its presence.
Define obligate anaerobes.
Bacteria that do not need oxygen to live and are killed by oxygen.
Define facultative intracellular bacteria.
Bacteria that can live in or outside a cell.
Define obligate intracellular bacteria.
Bacteria that can only survive in a host cell (but it is not a virus).
State the 4 phases of the basic bacterial growth curve.
Lag phase
Exponential phase
Stationary phase
Death phase
What is the lag phase of the basic bacterial growth curve?
The time interval between inoculation of bacteria and measurable growth.
What is the exponential phase of the basic bacterial growth curve?
The healthiest state for a bacteria, where growth occurs faster than death. Doubling of population occurs at a constant rate.
What is the stationary phase of the basic bacterial growth curve?
Population growth = population death so no net growth.
Nutrients have been used up & waste is building up so it is inhibiting growth.
What is the death phase of the basic bacterial growth curve?
Incubation that has continued past the stationary phase.
Phase at which spores are formed.
What is a direct microscopic count in bacteriology?
Counting cells on square paper under microscope
What are disadvantages of a direct microscopic count?
No distinction between live & dead cells
Time-consuming
Small cells can go unnoticed or debris can be mistaken for cells
A phase contrast microscope must be used if no stain is used
What is a direct microscopic count with flow cytometry in bacteriology?
Using laser beams, fluorescent dyes & electronics to count cells in a liquid.
What are disadvantages of direct microscopic count with flow cytometry?
Expensive
What is a viable count in bacteriology?
A measure of the living & reproducing cells.
What should the colony size for a viable count be?
Between 30-250 cells.
What are psychrophiles?
Microorganisms that grow best at 4°C.
What are mesophiles?
Microorganisms that grow best at 39°C.
What are thermophiles?
Microorganisms that grow best at 60°C.
What are hyperthermophiles?
Microorganisms that grow best at temperatures above 80°C.
What are acidophiles?
Bacteria that grow best at pH < 6.
What are alkaliphiles?
Bacteria that grow best at pH > 7.
