Experiments 12, 20, 26 Flashcards
Experiment 12: What is enrichment media?
enhances growth of desired microbes with added chemicals
Experiment 12: Differential media:
distinguish between bacteria by metabolism or waste
Experiment 12: Selective media:
select against unwanted bacteria without inhibiting growth
In experiment 12 (special media for isolating bacteria), how did you identify which organisms were in the unknown broth?
By comparing the results of the agars to the reference agars we created and visibility noting the similarities and differences
Experiment 12: All organisms grew in the _______ agar
nutrient agar
Experiment 12: How did the results observed on the mannitol salt agar and EMB agar correlate to the gram reaction of the bacteria?
Gram negative only grows on the EMB agar and gram positive only grows on the MSA
Experiment 12: which medium is selective?
Mannitol Salt Agar
Experiment 12: What is the purpose of peptone in the media?
It is used as a nutrient source of carbon, nitrogen and energy for growth
Experiment 12:What is the purpose of agar in the media?
to solidify bacteria in the media
Experiment 12: What ingredient makes mannitol salt selective?
high concentrations of salt
Experiment 12: Which bacteria was metallic green?
E Coli
Experiment 12: Nutrient agar that contains vanomycin is (selective or differential) for ________________
selective for vanomycin resistant organisms
Experiment 12: EMB agar that contains sorbitol is used to (select or differentiate) E. Coli
selective
Experiment 12: Nutrient agar with tellurite is (selective or differential) for _______________
selective for corynebacterium diphteriae
Experiment 20: Summarize the effect of temperature on growth of E. Coli
There is an optimal temperature for E coli growth (37 degrees C), any hotter or colder will not achieve the same reuslts
Experiment 20: Why aren’t you likely to get lag and death phases in this experiment?
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
Experiment 20: What is the optimum temperature for human pathogens?
37 degrees C
Experiment 20: What is the effect of temperature on enzymes?
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)
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.
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
Experiment 20: Why is turbidity not an accurate measurement of viable bacteria in a culture?
Because you are not necessarily measuring only living cells. Ruptured cells and waste, etc are often still present and also being measured
Experiment 26: What is a surgeon trying to accomplish with a 10-minute scrub with a brush followed by and antiseptic?
scrubbing is an attempt to dislodge as many microbes as possible. Antiseptic is used to kill as many microbes as possible
Experiment 26: How do normal microbiota and transient microbiota differ?
Normal= permanent microorganism Transient= present only for days or weeks
Experiment 26: If most of the normal microbiota and transient microbiota aren’t harmful on skin, then why must hands be scrubbed before surgery?
Because externally they may not be harmful, but internally they can cause infection
What type of soap holds the highest percentage of bacteria?
bar soap
What type of soap prevent bacteria from getting into the soap?
pump soaps
