psychorphiles: grow at cold temps, 0-15 degrees celcius
psychotrophs: 20-30 degrees celcius
Temperature --> mesophiles
grow best at moderate temps, 25-40 degrees celcius
most common type bacteria (human pahtogens)
bacteria that only grows above 45 degrees celcius
none are pahtogenic to human
what is a minimm growth temperature?
lowest temp at which an organism grows
what is an optimal growth temperature?
highest temp at which growth occurs
what happens to hydrogen bonds when they are influenced by temperature?
they break and cause a different protein to make be formed.
Most bacteria prefer what PH?
neutral PH 7.0 (6.5-7.5)
grow at extremely low ph's 0-5.5
Tell me about H. Pylori
causes stomach ulcers
can tolerate stomach acid, which can get as acidica s 1.0
it burrows its way into the lining of the stomach
produces chemical buffers
How does osmotic pressure affect bacteria?
exerted on them by surroundings (mainly water)
whats a halophil? (3 types)
Obligate: require high salt concentrations to grow
Faculative: can live w/ or w/o high salt concentrations
Extreme: can grow in the presence of very high salt concentrations
Carbon, Hydrogen, Oxygen is required for?
nitrogen is required for?
for making some bacterial amino acids and nucleic acids
what is sulfur required for?
making some bacterial amino acids
phosphorous is required for?
making bacterial nucleic acids, membrane phopholipid bilayer and ATP
Potassium, Magnesium and Calcium are required for?
functioning of some bacterial enzymes
what is iron required for?
for bacterial metabolism
dependent on presence of oxygen
does not require oxygen but grows better in the presence of oxygen
dies in the presence of oxygen
requires oxygen levels between 2-10%
grows the same w/ or w/o oxygen
Bacterial Growth Curve.
lag phase: bacteria are adjusting to their enviro. & may have to synthesize enzymes to utilize the nutrients available in the enviro. little if any binary fussion occurs.
log phase: the # of bacteria doubles and increases expotentially & will have reached the constant minimum generation. can only be sustained as long as the enviro is compatiable and has proper nutrition
stationary phase: waster level begins to rise, nutrient level begins to fall. # cells dying= # cells divide
death pahse: continous decline in # of dividing cells. exhaustion of nutrients & build up of toxic waste