Experiments 12, 20, 26

Question 1

Experiment 12: What is enrichment media?

Answer 1

enhances growth of desired microbes with added chemicals

Question 2

Experiment 12: Differential media:

Answer 2

distinguish between bacteria by metabolism or waste

Question 3

Experiment 12: Selective media:

Answer 3

select against unwanted bacteria without inhibiting growth

Question 4

In experiment 12 (special media for isolating bacteria), how did you identify which organisms were in the unknown broth?

Answer 4

By comparing the results of the agars to the reference agars we created and visibility noting the similarities and differences

Question 5

Experiment 12: All organisms grew in the _______ agar

Answer 5

nutrient agar

Question 6

Experiment 12: How did the results observed on the mannitol salt agar and EMB agar correlate to the gram reaction of the bacteria?

Answer 6

Gram negative only grows on the EMB agar and gram positive only grows on the MSA

Question 7

Experiment 12: which medium is selective?

Answer 7

Mannitol Salt Agar

Question 8

Experiment 12: What is the purpose of peptone in the media?

Answer 8

It is used as a nutrient source of carbon, nitrogen and energy for growth

Question 9

Experiment 12:What is the purpose of agar in the media?

Answer 9

to solidify bacteria in the media

Question 10

Experiment 12: What ingredient makes mannitol salt selective?

Answer 10

high concentrations of salt

Question 11

Experiment 12: Which bacteria was metallic green?

Answer 11

E Coli

Question 12

Experiment 12: Nutrient agar that contains vanomycin is (selective or differential) for ________________

Answer 12

selective for vanomycin resistant organisms

Question 13

Experiment 12: EMB agar that contains sorbitol is used to (select or differentiate) E. Coli

Answer 13

selective

Question 14

Experiment 12: Nutrient agar with tellurite is (selective or differential) for _______________

Answer 14

selective for corynebacterium diphteriae

Question 15

Experiment 20: Summarize the effect of temperature on growth of E. Coli

Answer 15

There is an optimal temperature for E coli growth (37 degrees C), any hotter or colder will not achieve the same reuslts

Question 16

Experiment 20: Why aren’t you likely to get lag and death phases in this experiment?

Answer 16

Because the bacteria has already been growing and are past that point in the growth curve. No death phase because the bacteria won’t die in a substantial amount in the 60 minute lab time frame

Question 17

Experiment 20: What is the optimum temperature for human pathogens?

Answer 17

37 degrees C

Question 18

Experiment 20: What is the effect of temperature on enzymes?

Answer 18

temperature increases activity of enzymes up to a certain temperature, after the maximum temperature the protein will denature and stop working (usually above 37 degrees)

Question 19

Experiment 20: If you have isolated a bacterium that produces an antibiotic. The bacterium grows well at 37 degrees but produces antibiotics best at 30 degrees C. Design a procedure to maximize the biomass (total cells) and yield of the antibiotic.

Answer 19

Grow the bacteria at 37 degrees until you have sufficient growth of the bacteria, then put the culture to 30 degrees so they will produce the antibiotic

Question 20

Experiment 20: Why is turbidity not an accurate measurement of viable bacteria in a culture?

Answer 20

Because you are not necessarily measuring only living cells. Ruptured cells and waste, etc are often still present and also being measured

Question 21

Experiment 26: What is a surgeon trying to accomplish with a 10-minute scrub with a brush followed by and antiseptic?

Answer 21

scrubbing is an attempt to dislodge as many microbes as possible. Antiseptic is used to kill as many microbes as possible

Question 22

Experiment 26: How do normal microbiota and transient microbiota differ?

Answer 22

Normal= permanent microorganism
Transient= present only for days or weeks

Question 23

Experiment 26: If most of the normal microbiota and transient microbiota aren’t harmful on skin, then why must hands be scrubbed before surgery?

Answer 23

Because externally they may not be harmful, but internally they can cause infection

Question 24

What type of soap holds the highest percentage of bacteria?

Answer 24

bar soap

Question 25

What type of soap prevent bacteria from getting into the soap?

Answer 25

pump soaps