microbiology lab practical 2 Flashcards
Standard autoclave procedure
121 degrees C, 15 pounds of pressure, 15 minutes
Standard incubation procedure
37 degress C, 48 hours
Streak plate: purpose
To get isolated colonies to work with.
Streak plate: Where do the bacteria come from?
a patient specimen
Inoculation plate: purpose
To get a pure culture.
Incoculation plate: Where do the bacteria come from?
the streak plate
Gram stain: function and result of
Step 1: crystal violet
Function: stain all the bacteria purple
Result: G+: purple G-: purple
Gram stain: function and result of
Step 2: iodine
Function: fix the crystal violet even stronger to
the G+ bacteria.
Result: G+: purple G-: purple
Gram stain: function and result of
Step 3: ethyl alcohol
Function: wash the crystal violet out of the
G- bacteria.
Result: G+: purple G-: clear
Gram stain: function and result of
Step 4: safranin
Function: stain the G- bacteria pink
Result: G+: purple G-: pink
chains ( stained blue
Kingdom: Monera Where found: dirt/dust
Clinical significance: lung infection or a blood
infection with a compromised immune system.
Scientific name: Bacillus subtilis
pink globs
Kingdom: Monera Where found: the intestine of animals
Clinical significance: UTI, diarrhea, blood infections
Scientific name: E. coli
blueberries
Kingdom: Monera Where found: on skin
Clinical significance: UTI in females
Scientific name: Staphylococcus saprophyticus
What microbes predominate in milk early on–
when we first buy the milk?
Streptococcus and Lactobacillus
What microbes predominate in milk later on–
when the milk has gone really bad?
Pseudomonas and yeast
What microbe is mainly responsible for
making milk go sour?
Lactobacillus
What two genus of bacteria are found on the surface
of most raw chicken at the store?
Salmonella and Campylobacter
Gram stain result: Corynebacterium xerosis
G+ rod, individual cells, no endspores
Gram stain result: Lactobacillus
G+ rod, in chains, no endospores
Gram stain result: Pseudomonas, Salmonella,
Campylobacter
They are all a G- rod, individual cells.
Independent variable
The variable whose effect is being measured.
Dependent variable
The variable that might be affected by
the independenet variable.
Control Group, Experimental Group
These two groups receive the exact same living
conditions, except the control group does not
receive the independent variable and the
experimental group does receive the
independent variable.
Sample hypothesis: Ingesting saccharin will cause an
increase in bladder cancer rates among lab rats.
Identify: independent variable, dependent variable,
control group, experimental group
Independent variable: ingesting saccharin
Dependent variable: bladder cancer rates
Control group: a group of lab rats that receive
no saccharin in their diet.
Experimental group: an equal number of lab
rats that receive saccharin in their diet
every day.
Sample hypothesis: the use of smokeless tobacco will
cause an increase in oral cancer rates.
Identify: independent variable, dependent variable,
control group, experimental group
Independent variable: using smokeless tobacco
Dependent variable: oral cancer rates
Control group: a group of people who do not use
smokeless tobacco
Experimental group: an equal number of people
who do use smokeless tobacco
Phenol: how used/antiseptic
It is put into some throat lozenges:
Antiseptic: Yes
Hexachlorophene: how used, antiseptic
It is added to some types of soap and detergent.
Antiseptic: yes
Cresol: how used, antiseptic
It is the active ingredient of Lysol.
Antiseptic: no
Alcohol: how used, antiseptic
The active ingredient of Scope and Listerine.
Also used on skin (rubbing alcohol).
Antiseptic: yes
Chlorine: how used, antiseptic
The active ingredient of Bleach.
Also used in much smaller doses in
swimming pools and drinking water.
Antiseptic: the high dose used in
Bleach: no the much smaller
dose used in swimming pools and
drinking water: yes
Iodine: how used, antiseptic
Kills bacteria excellent on the skin.
Antiseptic: yes
Hydrogen peroxide: how used, antiseptic
Used on cuts sometimes.
Antiseptic: yes
Results: Bacteria put in to a 20% NaCl solution:
E. coli 50 colonies
Staphylococcus epidermidis 300 colonies
Conclusion?
The results are expected.
Results: Bacteria put into a 20% NaCl solution.
E. coli 300 colonies
Staphylococcus epidermidis 50 colonies
Conclusion?
The results are not expected.
Results: Bacteria boiled for 15 minutes:
E. coli 0 colonies
Bacillus subtilis 80 colonies
Conclusion?
The results are expected.
Results: Bacteria boiled for 15 minutes
E. coli 80 colonies
Bacillus subtilis 0 colonies
Conclusion?
The results are not expected.
Results: flaming bacteria/endospores for 1 second:
Growth
Conclusion?
The results are expected.
Results: flaming bacteria/endospores for 1 second.
No growth
Conclusion?
The results are not expected.
Results: flaming bacteria/endospores for 5 seconds:
Growth
Conclusion?
The results are not expected.
Results: flaming bacteria/endospores for 5 seconds.
No growth
Conclusion?
The results are expected.
