Microbial growth Flashcards
Define microbial growth
Growth in population
Increase in number of cells
Define maximum growth temperature
The highest temperature at which any growth occurs.
Define minimum growth temperature
Lowest temperature at which any growth occurs
Define optimum growth temperature
Temperature at which the growth rate is the highest.
Define psychrophiles
Cold loving
Optimum growth temperature: 4C-10C
Define psychrotrophs
Tolerate cool temperatures
Optimum growth temperature: 20C-25C
Define mesophiles
Loves core body temperature
Optimum growth temperature: 37*C
Define thermophiles
Heat loving
Optimum growth temperature: 40C-60C
Define extreme thermophiles
Optimum growth temperature: >80*C
Define acidophiles
Grow best in environments below pH 5.5
Define neutrophiles
Grows best in environments between pH 5.5 - 8.5
Define alkaliphiles
Grows best in environments above 8.5
Define pure culture
A colony of microbial growth that only has one species or strain of microorganisms.
Define colony
A population of cells arising from a single cell or spore or from a group of attached identical cells.
Specimens
Sample that typically contains many different microorganisms.
How can we isolate a single species from a mixed culture?
Streak plate technique for isolation.
Define selective medium
media that suppresses growth of unwanted microorganisms and encourage growth of desired microbes.
Define differential media
Media that helps distinguish colonies of different microbes
Define binary fission
Bacterial reproduction
1) cell elongates and DNA repilacates
2) Cell wall and plasma membrane begin to constrict.
3) Cross-wall forms completely separating the two sides; each with their own DNA.
4) Cells separate
Define generation time
The time required for one population to doubling in numbers.
Varies with species and environmental conditions.
Define biofilm
3-dimensional film that aids the colony in sharing nutrients, sheltering from harmful factors, cell to cell communication.
Define Quorum
A form of bacterial communication. Individual cells can sense that accumulation of signaling molecules.
-Informs individual cells about surrounding cell density.
-May change the behavior (gene expression) of individual cells. Resulting in a coordinated response by the whole population.
Define strict halophiles
Microorganism that require high osmotic pressure.
Hypertonic environments.
High concentrations of Salt (>3% salt)
Define faculative halophiles (osmotolerant)
Microorganism that can tolerate higher osmotic pressure.
Define autotroph
Organism capable of synthesizing its own food from inorganic substances using light or chemical energy.
