Lecture 5: Flashcards
What is a major environmental factor controlling microbial growth?
temperature
Cardinal temperatures
the minimum, optimum, and maximum temperatures at which an organism grows
Optimum
- where organism grows FASTEST (according to temp)
- you can give it the temp it likes most (optimal temp), but if nutrient [ ]’s are not on point, pH isn’t controlled, salt [ ] isn’t good etc. it doesn’t matter if you give optimal temp
- but it’s just 1 variable - more needs to be considered for the reality
enzymatic reactions occurring at maximal possible rate
These cardinal temperatures are characteristic of…
each different organism
Minimum temp
mem. specifically solidified
- LESS mobile “sleeping” –> metabolically inactive
- membrane gelling; transport processes so slow that growth cannot occur
Maximum temp
mem. melted
- higher temp
- death
- breakage of VdW’s b/c of increased movement
- protein denaturation; collapse of the PM thermal lysis
If membrane is melted what has happened to its structure and what does it mean abt the cells state
falls apart - completely dismembers - no shape so cell dies b/c PM all about shape (butter in microwave)
- CELL DIES ABOVE MAX GROWTH TEMP
When membrane is solid has the cell lost its membrane integrity or is it just less mobile?
less mobile –> “sleeping”
- metabolically inactive but if you put it at high temps it will become active again (this is why your old not to freeze thaw things again and again)
Min to optimum temp if characterized by what on the graph?
very gradual slope temp decrease doesn’t have a dramatic effect as temp increase
What will mem. state be at its optimum (necessary state for PM)?
semi-fluid
- best growth rate possible
Optimum to max we see…
substantial drops in the growth rate that occur within that region
What will happen to the movement & therefore VdW’s interactions within the PL tails at excessively high temps?
breakage of VdW’s b/c of increase movement
-melted membrane; puddle that loses function and loses structural integrity
What will happen to the movement & therefore VdW’s interactions within the PL tails at cold temps?
membrane phospholipids move LESS in COLD allowing MORE van der waals to form –> “gelling” or solidification
- but mem’s need to be semifluid
Describe what happens to the protein (has to have certain shape) when HEAT is added vs when its in COLD temps
a protein needs to have a certain shape to function properly
when HEAT is added breaks H-bonds, VdW’s & ionic bonds DENATURED = non-functional
when COLD is added move LESS & ionic, H-bonds & VdW’s form DENATURED - COMPACT b/c increase # of bonds
- lil easier to recover from
- functional for cold loving organisms
Which is more lethal high or cold temps?
HIGH TEMPS= DEATH
How can microorganisms be classified into different groups name the groups?
Microorganisms can be classified into groups by their growth temperature optima
- Psychrophile
- Mesophile
- Thermophile
- Hyperthermophile
Psychrophile:
low temperature
phile= friend in greek
Mesophile:
midrange temperature
- include us & medically relevant bacteria & flora within the body
- biggest group
Thermophile:
high temperature
Hyperthermophile:
very high temperature
Where can mesophiles be found?
organisms that have midrange temperature optima (~38 degrees celsius)
• Warm-blooded animals (include us, cows, goats etc.)
- endothermic organisms that have bacteria living in them
• Terrestrial and aquatic environments
- diff bodies of water
• Temperate and tropical latitudes
- warm-temp within this range most of the time
ex- e.coli
Cold-Loving Microorganisms
- Extremophiles
- Psychrophiles
- Psychrotolerant
Extremophiles
• Organisms that grow under very hot or very cold conditions
* prefer very extreme temps
OR like LOW pH/HIGH pH/HIGH [salt] etc.
Psychrophiles
• Organisms with cold temperature optima (<20oC)
- friends of cold temps
• Inhabit permanently cold environments
- Deep ocean, Arctic and Antarctic environments
ex- polarmonas vasculota