Lecture 18: Microbial Growth Flashcards
defined medium
know exactly what went in
complexed medium
composition unknown
minimal medium
meets minimum requirements
selective medium
favours growth of desirables & restricts growth of undesirables
differential medium
distinguished between types
why is agar used in the lab?
remains firm below 65 degrees and is hard for microbes to digest
batch
liquid culture in a vessel
are batch open or closed systems
closed
what is 1 negative of batch?
limited growth
lag phase
bacteria is adapting to new environment
exponential phase
when most active growth occurs
stationary phase
when no active growth & balancing cell death & division
declining phase
bacteria runs out of resources to survive
chemostat
continuous system where bacteria is fed with fresh medium
is chemostat open or closed system
open
what controls growth rate in chemostats?
dilution rate
what does chemostat control?
growth rate & yield
what is goal of chemostat
to keep bacteria in their exponential phase
biofilms
attached communities
T of F: biofilms can be closed or open systems
true
how are growth curves established?
measures growth & population
example of direct count method for bacteria
microscope
2 examples of viable count method for bacteria
spread-plate & pour-plate
what must be done during spread/pour plate methods in order to be able to count the bacteria?
dilution
what is turbidimetric?
optical density to count bacteria
how does optical density work for counting bacteria?
uses light pass to through & measure density of bacteria blocking the light
what kind of count does optical density give?
total count of population
what does colony forming unit (CFU) tell us?
viable count
what 2 things double during cell growth?
cell mass & cell number
what type of graph is growth plotted on?
semi-log scale
generation time
amount of time it takes to double population
specific growth rate
rate at a specific time
psychorophile temp requirement
below 0 - 10
mesophile temp requirement
10 - 50
psychotolerant temp requirement
0-42
thermotolerant temp requirement
10-55
thermophile
40-70
hyperthermophile temp requirement
90-115
neutrophile pH range
5.5 - 8
acidophile pH range
0- 5.5
Alkaliphile pH range
8- 14
halotolerant NaCl % range
0-11 %
nonhalotolerant NaCl % range
1-2 %
halophile NaCl % range
0-12%
extreme halophile NaCl % range
10 % +
what does Thioglycolate do?
reduces O2 concentration
obligate aerobe vs obligate anaerobe
aerobe- grows @ top
anaerobe- grows @ bottom
facultative anaerobe/aerobe
grows best at top but can also grow at bottom
microaerophillic
grows in between levels
aerotolerant anaerobe
grows everywhere
oxic vs anoxic zone
oxic- top
anoxic- bottom
candle jar method
chemical reaction inside a jar to remove O2
what type of viruses can cause plaque formation?
lytic
what do viruses need in order to be grown?
living host cells
