MIBO Ch 4 Dynamics of Microbial Growth

binary fission

asexual reproduction by separation of the cell into two identical daughter cells

generation time

time it takes for the population to double

biofilm

cause slipperiness of rocks in stream bed, slimy “gunk” in sink drains, scum in toilet bowls, dental plaque

pre culture

population of cells derived from a single cell; allows study of a single species

closed system (batch cultures)

culture in which nutrients are not added, nor are wastes removed

lag phase

number of cells doesn’t increase

adaptation

cells begin synthesizing enzymes required for growth in the new environment

exponential/log phase

population doubles each generation

most sensitive to antibiotics at this point

primary metabolites synthesized, secondary metabolites towards end

primary metabolites

amino acids

nucleic acids

vitamins

alcohol

secondary metabolites

antibiotics

color pigments

toxins

stationary phase

nutrient levels too low to sustain growth

new cells made at same rate as old cells die

continue to produce secondary metabolites

death phase

total number of viable cells decrease

pyschophile

-5-15C

artic and antartic

extremophile

psychrotroph

15-30C

refrigerator spoilage

mesophile

25-45C

pathogens and most environmental organisms

thermophile

45-70C

hot springs, compost heaps

hyperthermophile

70+C

thermal vents

extremophile

thermotolerant

able to survive exposure to high temps for a while, but don’t grow

aerobic

o2 is present

anaerobic

o2 is absent

obligate aerobe

grows only when o2 is available

requires o2 for respiration

facultative anaerobe

grows best when o2 is available, but also grows without it

uses o2 for respiration, if available

obligate anaerobe

cannot grow when o2 is present

does not use o2

mircoaerophile

grows only if small amounts of o2 are availalbe

requires o2 for respiration

aerotolerant anaerobe

grows equally well with or without o2

does not use o2