Microbiology Lab 3 Flashcards

Terms Definitions
Baker's yeast
Sacchaomyces cerevisiae
Staphylococcus aureus
Coagulase- positiveNovobiocin- highly succeptible
Microorganisms must be transferred from one vessel to another or from stock cultures to various media for maintenance and study. Such a transfer is called____________.
Serratia marscesens
Gram negativeBact. temp- incubator showed a lot of growth, RT showed some
Micrococcus luteus
Endospore stain- none foundCatalase- positiveBact. O2- obligate anaerobe
Steptococci species are broken down into how many groups.
What is the comma cell shape?
What is the spiral cell shape?
What is the bacterial cellular structures that confers motilitiry
What are Antimicrobials of low molecular weight, produced by microorganisms that inhibit or kill other microorganisms?

What color does a gram positive organism appears
The process of converting proteins to Ammonia is called
What is when a characteristic is distinctive for a particular disease or condition?
What does dichotomous mean?
two catergories and classifications
When studying wet mounts, what organism did we observe and identify as engaging in brownian motion?
Staphylococcus Auerus
IMVIC test is useful for
the genus Enterobacteriaceaespecifically to distinguish between e. coli and e. aerogenes.
What Regulates the amount of light that reaches the slide?
Can S. pneumonia live in blood culture? MSA?
Lactose Fermentation
acidifies the medium and turns the litmus pink. This acid reaction begins with the splitting of the disaccharide into the monosaccharides glucose and galactose by the enzyme beta-galactosidase. Accumulating acid may form an acid clot.
Pneumocystis carinii
Part of normal flora. but causes pneumonia in immunosupressed individuals.
the uptake of naked DNA from the environment
What do Gram Positive cocci produce?
Endotoxins called hemolysins
What is an agent intended to destroy or irreversibly inactive specific viruses,bacteria,or pathogenic fungi, but not neccessarily spores on inanimate surfaces?
What is a retrovirus believed to be the causative agent for aids?
Voges-Proskeaur Test
If the final of further glucose oxidation is ACETYLMETHYLCARBINOL (AMC) it will produce an orangey-red broth after 30 minutes of vortexing.
What does 2H2O2 + Catalase produce?
2H2O + O2
What is glucose plus litmus milk tube?
Pyruvic Acid
What color does urea turn if bacteria is basic in Ureah broth?
In spore staining, what is the counterstain? How long is it applied?
20 seconds
Where do you find aerobic bacteria?
Top of medium
What are the 4 Gram staining regents used?

Crystal violet


Decolorizing agent

In the use of the bactercult tube lab we tested for organisms which commonly cause what?
At what temperature does the agar liquefy?
100 degrees Celsius
What is the lends in a compound microscope that is closest to the specimen?
objective lense
What is the cell shape that is a cross between cocci and baccilli?
Bacteria that thrive in very hot climates
Thermophiles (B. stearothermophilus)
What does formic acid + Formic hydrogen lyase produce?
CO2 + H2
What does the Ureah broth contain?
Phenol red pH indicator
What does the simmons citrate agar contain?
Sodium citrate
Ammonia salts
Bronthymol blue
What is the outer protein coat of an endospore that forms a protective barrier called?
Can S. aureus live in blood culture? MSA?
What is a darkfield microscope?
The background is completely light-free and objects in the field become brightly illuminated by rays of light from the illuminator
A magnifying lense with 10 x power and part of the eyepiece
ocular lens
Electrophoresis- DNA is negatively charged thus it
"runs to the red" positive electrode.
What do Beta Hemolysins do?
Complete destruction of RBCs and hemoglobin. It results in a clearing of the medium around the colonies
What is the purpose of serial dilutions?
Make counting more reliable
MacConkey plate: organisms changing from colorless to pink.
Lactose fermenters will appear pink, non-lactose fermenters will appear colorless. This is due to the addition of the indicator, neutral red.
How does lysine decarboxylase work
decarboxylates the amino acid lysine resulting in the production of the alkaline end-product cadaverine, by producing the enzyme lysine decarboxylase.
Lysine + Lysine decarboxylase = Cadaverine. The enzyme requires an acid pH for activation. IF the organism is capable of glucose fermenatation AND has the enzyme lysin decarboxylase, the
1)microbe ferments glucose, indicator turns yellow
2)lysine decarboxylase is activated
3) Cadaverine is formed, pH rises and teh media returns to ts original purple color
What is the procedure for Phenylalanine Deamination test?
Strak phenyalanine agar slant
Incubate at optimum temperature
Place 5-10 drops of 10% Ferric Chloride on the slant
How do you transfer bacteria? What instruments should be used?
Loops and Needles
What is a medium made of a specific composition that is known?
Defined medium
Schaeffer Fulton Endospore Stain method
Malachite green is the primary stain, which is forced into the spore by steaming the bacteria.Because the malachite green is water soluble it has a low affinity for cellular material, so the vegetative cells and mother cells can be decolorized with water, and counterstained with Safranin. All cells will show up pink or red, and the spores will be green. The bacteria is not spore forming unless you can find the spores inside the cell
The standard analysis of water tests the water supply for colliforms by a three-test profcess...
1.) Presumptive test2.) Confirmed test3.) Completed test
What is the formula for the single dilution?
volume of the sample____________________vol of sample + vol of the diluent
TSI possible results:red slant, red butt=red slant yellow butt=yellow slant yellow butt=Black=
red/red= nothing fermented no H2S produced.red/yellow= only glucose fermentedyellow/yellow= glucose and either both or one of the two sucrose/lactose was fermentedblack= H2S was produced and fermentation of sugars is obscured.
What kind of medium is used for the casein hydrolysis?
Skim Milk Agar
What are negative stains used for?
In studying the morphology of bacterial cells and characterizing some of the external structures, such as capsules, that are associated with bacterial cells
Lactose Fermenters on Endo Agar
They will appear red or pink and darken the mediumThis is due to a reaction with sodium sulfite with fermentation intermediate acetaldehyde
In the food analysis lab why were foods suspected of having either bacillus or clostridium species heated before being plated?
because these are endosporing bacteria and by heating vegetative cells are killed leaving the organisms in question.Also for CLOSTRIDIUM it was put in GASPAK where hydrogen is released and reacts with oxygen to form water and produces the anoxic conditions required for clostridium species to grow.
How did we extract a plasmid?(many chemicals involved)
Cell must first be lysed (lysozyme)The membrane must be disrupted (SDS, NaOH)Now you have the plasmid you need it to reanneal (Potassium acetate)also the plasmid reanneals in soln while the rest of the cells DNA is caught in complex with K+ (recall DNA is -ve)Lastly it is centrifuged and the soln (plasmid) is dried over isopropyl alcohol and later ethanol and allowed to sit in a buffer.
What is Common Source epdiemic?
When a disease is transmitted from an area such as a heating or cooling system of a building or contaminated water it infects many people all at once.
What is the purpose of the dilution experiment with the decontamination?
determine effective concentration of the disinfectant
The acid fast stain served what purpose?
used to differentiate the genus Mycobacterium which can cause TB and leprosy. CLUMPED RED RODS!
What are the three branches of pyruvic acid?
Lactic acid
Butyric Acid
CO2 + H2
How does phenol red change colors due to carbohydrates?
Fermentation of carbohydrates produces acid, causing the media to change from red to yellow
What is a pure culture?
Contains only a single kind of an organism
In the normal flora lab we saw the chocolate agar plate for the first time and incubated it in a closed container with a candle. What was the purpose?
Chocolate agar grows Neisseria species which thrive in microenviornments with high CO2 content and no O2 (acheived by the burning candle).
What bodily fluid should be tested with the bactercult tube?
Urine (it is a test for UTIs)
What is the purpose of a wet mount?
To check for motility in microorganisms.
What kind of test uses MR-VP Broth?
Methyl Red TEst and Voges Proskauer Test
What type of bacteria is mycobacterium smegmatis? What shape are they?
Acid fast; Gram positive
May be Y shaped or branched
The last of the three standard analysis of water tests is the COMPLETED TEST. In this test what is done? results?
Here a metallic green colony from the comfirmed test is used to innoculate a lactose fermentation tube and a nutrient agar tube for gram staining. this last step confirms that the organism is a gram-negative lactose fermenting rod.
What is the purpose of the slant streak method?
The purpose for streaking is for storage of microbiologic stock.
What is the lysine decarboxylase test used for?
Used to determine the ability of an organism to decarboxylate the amino acid lysine,
What are the seven steps of acid fast staining?
Cover smear w/ carbolfuchsin- 5 min
Acid alcohol-1 minute
Methylene blue-30 seconds
What are the two reasons to make sure your loop has cooled before scooping microbes?
1. could kill microbes2. burn them into the air
What is the purpose of the UV light experiment?
To determine to what extent plastic protects cells from the effects of UV light
Mueller-hinton plate was used in the lab. why was it used?
it was used as a rich medium to grow almost any bacteria. it was actually used to determine antibiotic resistance.
What are the five steps for capsular staining?
Organism is mixed in a drop of india ink
Ink suspension is air dried
Slide is gently heat fixed
Smear is stained with crystal violet for 1 minute
Crystal violet is washed off and blotted dry
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