Ch 5: Microbial Growth and its Control PART 2 Flashcards
what is binary fission
cells elongate to approximately twice their original length and then form a partition that constricts the cell into
two daughter cells
what is the septum in bacterial growth
The partition that forms between dividing cells
how long does septum formation last
until the daughter cells get pinched off
Can the pattern of binary fission have variation
yes
What is the definition pf sterilization
destruction or removal of all viable (?) organisms
What are endospores
spores that bacteria produces, that are very infectious
What type of antimicrobial method is effective against endospores
Sterilization
what is disinfection
killing, inhibition, or removal of disease causing (pathogenic) organisms –but not endospores
Where is disinfectants normally used
on inanimate objects
What type of agents are used of disinfecting
chemical agents
What is sanitization
reduction of microbial population to levels deemed safe
example of sanitization
dry handwashing gel
what is antisepsis
prevention of infection of living tissue by microorganisms
What are antiseptics
chemical agents that kill or inhibit growth of microorganisms when applied to tissue
What are examples of antiseptics
Alcohol 60-85%, certain soaps
Example of substances that can be used as antimicrobial growth methods (antiseptic, disinfectants sanitizers) depending on its concentration
Alcohols and hydrogen peroxide
What suffix indicates that the agent kills
-cide or -cidal
what is germicide
kills pathogens and many nonpathogens but not necessarily endospores
examples of agents are that germicides
include bactericides, fungicides, algicides, and viricides
what does -static suffix indicate
agents that inhibit growth
Examples of -static agents
bacteriostatic and fungistatic
What are the environmental limits on microbial growth
- Temp
- pH
- Osmolarity (the concentration of a solution expressed as the total number of solute particles per liter)
- Oxygen
- Pressure
can microorganisms be killed instantly
no
What is the pattern of microorganism population death
exponential
What are the 2 measures of the agents killing efficiency (of microorganisms)
- decimal reduction time
- persister cells are dead
What is the decimal reduction time
time to kill 90% of microorganisms
what are persister cells
Cells that don’t grow or die in the presence of antibiotics. Cells in viable but nonculturable (VBNC) condition
what happens if persister cells are not dead
once they recover they may regain the ability to reproduce and cause infection
what type of rate to microbes die at
logarithmic rate
At the logarithmic rate, what is the D-Value1
time to kills 90% of cells
What do 2 D-values show
time to kill 99% 0f cells
What do antimictobial agents do to the D-value
decreases it
What does a decreased D-value mean of killing cells
small D Value means the cells killed faster
Relation between growth rate and temp
Growth rate increases with temperature
Do proteins denature when temp is too low or too high
too high
what are the 4 types of microbial proteins
- Psychrophiles
- Mesophiles
- Thermophiles
- Extreme Thermophiles
What temp range did psychrophiles adapt to
0 - 20 C
What temp range did mesophiles adapt to
12 - 45 C
What temp range did thermophiles adapt to
40 - 80 C
What temp range did extreme thermophiles adapt to
65 - 113 C
What is the heat shock response in microorganisms
When bacteria cells are exposed to higher temperature, a set of heat-shock proteins (hsps) is induced rapidly and transiently to cope with increased damage in proteins.
What is heat shock a response to?
high temp
In what stressful conditions is the heat shock response induced
- Heat
- high salt concentration
- arid conditions
