Midterms_Microbial Growth Flashcards
Most frequently used method of measuring bacterial populations.
Plate count
Use a __________ to determine % transmission or absorbance.
Spectrophotometer
Cells division begins to slow down
Stationary phase
Period of most rapid growth. Number of cells produced > Number of cell dying
Log phase
Factors that slow down microbial growth
(AALI): Accumulation of toxic waste materials, acidic pH of media, limited nutrients, insufficient oxygen supply
As bacteria multiply in media, it becomes ____.
Turbidity
One advantage is that colonies will be on surface and not exposed to melted agar
Spread plate
Used mainly to measure bacteria that will not grow on solid medium
Most Probable Number (MPN)
Cells are at highest metabolic activity
Log phase
Used to measure small quantities of bacteria
Filtration
Not useful for heat sensitive organisms and colonies appear under agar surface
Pour Plate
Stain is added to visualize bacteria
Direct Microscopic Count
Cell number decrease at a logarithmic rate
Death phase
Bacteria grow and divide by ________, a rapid and relatively simple process.
Binary fission
May last from one hour to several days
Lag phase
Cells lose their ability to divide
Death phase
Cells are most susceptible to adverse environmental factors at this stage
Log phase
Period of adjustment to new conditions
Lag phase
Overall cell number does not increase
Stationary phase
Population size begins to decrease. Number of cells dying»_space;> number of cell produced
Death phase
Growth Cycle (4)
Lag phase, Log Phase, Stationary Phase, Death/Decline Phase
Phase of intense metabolic activity, in which individual organisms grow in size
Lag phase
Require a high concentration of bacteria
Direct Microscopic Count
Population size begins to stabilize. Number of cell produced=Number of cells dying
Stationary phase
Refers to an increase in cell number, not in cell size.
Microbial Growth
Little or no cell division occurs, population size doesn’t increase
Lag phase
Cells begin to divide and generation time reaches a constant minimum.
Log phase
A few cells may remain alive for a long period of time
Death phase
