Chapter 6/13: Enumerating Microbes Flashcards
What type of microbe counting system involves loading a known volume on a grid and counting under a light microscope?
Direct count
What type of microbe counting system uses a slide with an etched grid?
Direct count
What type of microbe counting system involves diluting a culture in a series?
Viable cell counting
What type of microbe counting system measures colony-forming units (CFUs) per milliliter of initial culture?
Viable cell counting
What microbe counting system uses a filter apparatus if the cells are already very diluted?
Viable cell counting
What type of microbe counting system uses a spectrophotometer to give a rough measure of cell density in a tube?
Turbidity
Which phase in a microbial growth curve represents when microbes are gearing up for steady growth but not dividing?
Lag phase
Which phase in a microbial growth curve represents when microbes are replicating at a constant and steady exponential rate?
Log phase
Which phase in a microbial growth curve represents when replication has either halted due to lack of nutrients and excessive wastes, or the rate of replication is now equal to the death rate?
Stationary phase
Which phase in a microbial growth curve represents when nutrients are depleted and waste levels are high, or when cells are dying at a steady exponential rate?
Death phase
What term describes the time to double the population in the exponential phase?
Generation (doubling) time
What term describes the number of generations per unit of time?
Growth rate
What term describes the maximum population density and/or amount of cellular material produced by the culture?
Growth yield
Which three values can a microbial growth curve determine?
Generation time, Growth rate, Growth yield
What equation can be used to predict cell numbers in a population?
Nt = No x 2^n
What does No represent?
Original population #
What does Nt represent?
in population at time t
What does ānā represent?
generations over the time period
