Defined media

. ingredients are exact and known; Undefined – the ingredients are known but not the exact quantities

All-purpose medium

used to increase the number of species grown

Differential medium

has an indicator to inform you if a product was made or digested (pH indicator)

Explain why there is no universal mediumcapable of growing all bacteria.

Microbes frequently require very specific nutrients and enviornments in which they thrive and grow.

Name five all-purpose media.

1. TSA
2. blood agar 
3. Muller- hinton
4. nutrient agar
5. brain heart infusion agar

Alpha hemolysis

greenish/browning of blood agar; partial destruction of RBCs

Beta hemolysis

clearing of blood agar; complete destruction of RBCs and hemoglobin

Gamma hemolysis

no change in blood agar, bacteria is simply growing; nonhemolysis

Understand why,when streaking a blood agar plate, the medium was stabbed with the loop upon completion of the streaking.

Hemolysins produced by streptococci ( streptolysins ) express optimally in anaerobic conditions, so the stabs encourage streptolysin activity because of the reduced oxygen concentration of the subsurface environment.

Assuming that all of the organisms cultivated in this exercise came from the throats of healthy students, why is it important to cover and tape the plates?

prevents contamination of plate and also because microbes are opportunistic and not always pathogenic

Why is the streak plate preferred over the spot inoculations in this procedure?

Quadrant streak is better for colony isolation as you start out with a much denser sample and then isolate it down , making the test more reliable

Pseudomonas Agar F

enhances bacterial generation of fluorescein (fluorescent pigment that glows yellow-green) and inhibits formation of pyocyanin (a blue-green nonfluorescent pigment)

Pseudomonas Agar P

enhances bacterial formation of pyocyanin (blue-green pigment) and inhibits generation of fluorescein (fluorescent pigment, glows yellow-green)

Describe the value of exoenzymes to bacteria

Exoenzymes can breakdown macromolecules (i.e. starch) into smaller molecules that can be taken through the cell's membrane

Suppose you had poured iodine on your plate and noticed clearing in the inoculated area, as well as around both of your transferred cultures.

1. What are some possible explanations of this occurrence?

Starch was not mixed properly, clearings suggest contamination not seen before iodine was added

How would you expect both positive and negative results to be affected if you were to add glucose to the medium?

The bacteria expected to eat starch will first use glucose since it ’ s easier to use as a substrate, so we won't be able to test for starch depletion using Iodine anymore because positive colonies may no longer test positive

Exoenzyme

Digestive enzyme excreted from cells to then be phagocytized for nutrient absorption within the cell

Endoenzyme

Non-digestive enzyme that functions within the cell. Most enzymes fall under this category

Hydrolyze

add water to split molecular bond

Understand the selective and differential aspects of MacConkey Agar

..

How is MacConkey Agar modified to allow the study of Enterococcus spp. and Staphylococcus spp

...

What is the complete definition of a coliform?

______ are a group of bacteria that are used as indicators of the potential presence of pathogens, viruses or parasites in a sample.

These microbes are defined as a group of bacteria having specific properties including the ability to grow at 35C in the presence of bile salts and able to ferment lactose.

What defines the family Enterobacteriaceae?

a family of gram-negative, facultatively anaerobic, rod-shaped bacteria, usually motile, made up of saprophytes and plant and animal parasites of worldwide distribution, found in soil, water, and plants and in animals from insects to humans.

have been responsible for as many as half of the nosocomial infections reported annually in the United States, most frequently by species of Escherichia, Klebsiella, Enterobacter,Proteus, Providencia, and Serratia.

What seperates a coliform from enterobacteriaceae?

Coliforms are able to ferment lactose