Lab Exam 1

What is the purpose of streaking for isolation?

To dilute a bacterial sample to get isolated colonies.

What does Turbid mean?

Cloudy broth meaning bacteria had grown.

What is a Pellicle?

Bacteria growing on top of broth.

What is Sediment?

Bacteria growing on bottom of the broth.

What does facultative mean?

They can use two pathways.

How does fermentation start?

With the breakdown of the Carbon Source (Sugars).

What are the results if you mix water and yeast?

No foaming meaning that fermentation did not occur.

What are the results if you mix water, yeast, and sugar?

Foam forms, meaning that carbon dioxide was produced, so fermentation occurred.

What are the end products of fermentation?

ATP, Carbon dioxide, and Ethanol.

If there were negative results in fermentation, why did fermentation not take place?

No carbon source.

Why do short wavelengths have a better resolution?

Able to fit between and around very small objects.

What is the purpose of Immersion Oil?

Eliminate bending of light as light passes from the glass slide to the lens.

What is the total magnification of 4X, 10X, 40X, and 100X?

40X, 100X, 400X, 1000X.

What is Chromagen?

Colors a stain.

What is another word for Emulsions?

Smear.

What is the purpose of Heat fixing a smear?

Keep cells stuck on slide and to kill bacteria.

What is the differential step?

Decolorizer.

What color do gram negatives stain?

Pink.

What color do gram positives stain?

Purple.

What color will cells stain if you forget crystal violet?

Pink and it’s a false negative test.

What color will cells stain if you forget the decolorizer?

Purple and it’s a false positive test.

What color will cells stain if you forget iodine?

Pink and it’s a false negative test.

What color will cells stain if you forget safranin?

Gram +: Purple and Gram –: Clear.

What is the purpose of Catalase?

Differentiate between gram positive bacteria.

What does it mean when we have a positive Catalase test?

Bubbles, has catalase, and likely not streptococcus or Enterococcus.

What does it mean when we have a negative Catalase Test?

No bubbles, does not contain catalase, and likely Streptococcus or Enterococcus.

What is the purpose of Coagulase?

Forms a fortress or agglutination protecting it from our immune system.

What are the results of a positive coagulase test?

Blue, agglutination, contains coagulase, and likely Staphylococcus Aureus.

What are the results of a negative coagulase test?

Purple, no agglutination, does not contain coagulase, and not likely Staphylococcus aureus.

Who is the trickster in a coagulase test?

Enterococcus faecalis.

What is the selective media in a MSA plate?

Salt.

What is the differential media in a MSA plate?

Mannitol.

What is the purpose of TSA plate?

To show growth of all bacteria and make sure they are alive.

What does it mean if there is growth on MSA plate?

Halotolerant.

What does it mean if there is no growth on MSA plate?

Not halotolerant.

What does it mean if there is a color change on MSA plate?

Can ferment mannitol.

What does it mean if there is no color change on MSA plate?

Cannot ferment mannitol.

What does it mean if there is growth and yellow color change in MSA plate?

Halotolerant, can ferment mannitol, likely Staphylococcus Aureus.

What does it mean if there is only growth in MSA plate?

Halotolerant, cannot ferment mannitol, likely Staphylococcus Epidermidis.

What does it mean if there is no growth or color change in MSA plate?

Not halotolerant, cannot ferment mannitol, likely Streptococcus Pyogenes.

Who is the trickster in MSA test?

Enterococcus faecalis.

What is the differential ingredient in blood agar plates?

RBC.

What is tested during a hemolysis test?

Toxin Hemolysins.

What do Hemolysins do?

They destroy not only RBC but WBC as well.

What is gamma hemolysis?

No hemolysis.

What is alpha hemolysis?

Incomplete hemolysis.

What is beta hemolysis?

Complete hemolysis.

What does the Beta hemolysis results tell you?

Clearing, likely strep pyogens or staph aureus.

What does Gamma hemolysis results tell you?

No clearing, likely staph epiderm or entero faecalis.

What is the purpose of esculinase?

Used to identify enterococcus faecalis.

What is the purpose of Bile?

Inhibits the growth of most gram positive bacteria.

What does a positive bile test mean?

Growth so it tolerates bile and darkening so it contains esculinase, likely enterococcus faecalis.

What does a negative bile test mean?

No growth, doesn’t tolerate bile, no darkening so not esculinase, likely not enterococcus faecalis.