-
pure culture
one in which all organisms are descendants of the same organism
-
sterile medium
free of all life forms
-
inoculum
growing organisms to be transferred
-
asceptic technique
method of preventing unwanted microorganisms from gaining access
-
colony
- visible mass of microorganisms growing on an agar surface
- usually originating from single organism or arrang. of organisms
-
three types of growth in broth culture:
- pellicle - mass floating at the top
- turbidity - general cloudiness throughout
- sediment - mass deposited at the bottom
-
obligate aerobe
grow only in the presence of oxygen
-
microaerophiles
require low conc. of oxygen to grow
-
obligate anaerobes
grow only without oxygen
-
aerotolerant anaerobes
cannot use oxygen but tolerate it fairly well
-
facultative anaerobes
grow with or without oxygen
-
psychrophiles
- cold loving bacteria
- -5C to 15C
-
mesophiles
- grow best at moderate temps
- 25C to 45C
-
thermophiles
- heat loving bacteria
- 45C to 70C
-
hyperthermophiles
- very high temps
- 70C to 110C
-
chromogenic
produce pigment during growth
-
water-soluble pigment
diffuses out of the organism and onto surrounding medium
-
water-insoluble pigment
does not diffuse out of organism
-
state three basic shapes of bacteria.
bacillus, coccus, spiral
-
state and describe five different arrangements of cocci.
diplococcus, streptococcus, tetrad, sarcina, staphylococcus
-
state and describe three different arrangements of bacilli.
bacillus, streptobacillus, coccobacillus
-
state and describe three different spiral forms.
vibrio, spirillum, spirochete
-
describe the appearance of a typical yeast.
- beaded appearance
- reproduce by budding
-
Define selective medium
inhibits growth of one group of organisms while permitting the growth of another
-
Define differential medium
- contains additives that cause an observable color change in the medium when a particular chemical reaction occurs
- this indicates whether or not the organism can carry out a specific biochemmical reaction
-
Define enrichment medium
- enhances the growth of certain organisms
- useful when you have a small number of an organism and want to grow a lot more
-
Define combination selective-differential medium
permits the growth of one group or organisms while inhibiting the growth of another AND differentiates those organisms that grow based on whether they can carry out particular chemical reactions
-
State the usefulness of Columbia CNA agar and MacConkey Agar
- Columbia CNA - selective for gram-positive bacteria, inhibits growth of gram-negative
- MacConkey - selective for gram-negative and lactose fermentation
-
Describe how E. coli appears on MacConkey agar
appears bright pink to red, surrounded by a pink halo
-
Describe how Enterobacter aerogenes would appear on MacConkey agar
appear bright pink to red, not surrounded by a pink halo
-
Describe how Salmonella would appear on MacConkey agar
colorless colonies
-
Formula for determining the number of CFUs per ml of sample when using plate count technique
number of colonies x dilution factor
-
State the principle behind the direct microscopic method of enumeration
the # of bacteria in a small known volume is directly counted microscopically and the # of bacteria in the larger original sample is extrapolated
-
State the formula for determining the number of bacteria per cc of sample when microscopic method of enumeration
average # of bacteria per large double-lined square x dilution factor of the large square x dilution factor of dilutions
-
State the function of a spectrophotometer
used to measure turbidity
-
State the relationship between absorbance (optical density) and the # of bacteria in a broth sample
- the absorbance is directly proportional to the cell concentration
- the greater the # of bacteria, the higher the absorbance
-
State the relationship between percent light transmitted and the number of bacteria in a broth sample
- the percent of light transmitted is inversely proportional to the bacterial concentration
- the greater the number of bacteria, the lower the percent light transmitted
-
Define genus and species
- genus = first name
- species = second name
-
State the length and width of an average rod-shaped/bacillus bacterium
-
State the diameter of an average coccus-shaped bacterium in micrometers
-
Define ocular lens
- aka eyepiece
- magnifies 10x
-
Define objective lens
- mounted on turret near stage
- yellow, blue, and white
-
State the reason for using immersion oil at 100x
the immersion oil traps the light and prevents the distortion effect that is seen as a result of the bending of the light waves
|
|
