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Microbiology Lab Final
Dr. Zac Microbiology 3400 - Lab Final Samrat Moitra
Terms in this set (84)
Mention two functions of HOPS in beer production
Seasons the beer and acts as a natural preservative
Glucose is fermented to produce .....
ethanol and CO2
Plaque Forming Unit
What enzyme converts Nitrate to Nitrite?
Name 2 groups of Fungi.
Zygomycota, Ascomycota, Chytridiomycota, Basidiomycota
Plaques are clear zones that represent where a phage is present and has killed the bacterium.
What reagent is used to test for presence of indole, and what is the positive color?
Kovax reagent is used and the positive color is red
What is produced when tryptophan is utilized. Name the enzyme involved
Indole is produced, and thyptophanase is the enzyme involved.
A/A results in KIA test indicate what carbohydrate has been fermented
both glucose and fructose have been fermented.
What are the two types of bacteriophage
Lytic and Lysogenic
MSA selects for what and prevents what
Selects for gram (+) and prevents gram (-) growth.
what is indicated by the presence of coliforms in the gum line sock in the peritoneal drop experiment?
Fecal bacteria (e. Coli)
What bacteria only grown without O2?
What indicator strip is placed in experiment to cultivate anaerobes?
Bacteria growing from 0 to 20 degrees are called
Candle jar is to analyze the growth of what and brewers jar analyzes what?
Candle jar is for microaerophilic and brewers jar is for anaerobic
Intense red color after adding Nitrate A and Nitrate B indicated the presence of what? This production is due to the reduction of nitrate by the enzyme what?
red color represents to product of nitrite because of nitrate reductase.
Intense red color after zinc dust is added indicates
Presence of neither enzymes.
Difference between TDP and TDT?
TDT is the termal death time which is the temp it takes to kill and organism in 10 minutes. TDP is the thermal is the thermal death point which is the temperature at which an organism is killed.
Explain why the control group plates with lids on had consistent growth of bacteria even after exposed to UV radiation.
The UV radiation was not effective in killing bacteria, because the lid was an effective barrier.
Explain why BGA (brilliant green agar) is both a selective and differential media.
BGA is both selective and differential because it selects for specific bacteria salmonella, but you can grow several types of salmonells such as salmonella typhi.
What is produced when tryptophanase is utilized and what is the enzyme?
Glucose is produced, and the enzyme is tryptophanase.
K/A results in KIA test indicate that which carb is fermented and which is not fermented?
Glucose is fermented but lactose is not
Name two methods used to reduce and control the growth of microbes in food products.
Salting and preserving
Staph A turns MSA plate yellow, but E. Coli cant. Why is this?
MSA selects for the growth of gram (+) bacteria. Since E. Coli is gram (-), its growth is inhibited on MSA plates.
MacConkeys Agar selects for what bacteria
Gram (-) and inhibits Gram (+)
Coliform bacteria act as
indicator species showing pathogenic bacterial contamination
What is a countable range when counting colonies from dilution experiment?
What is the decolorizer in gram staining experiments
Bacteria is .......... to the slide so that it can be stained without washing off.
Which magnification is the oil immersion lens
difference in gram + and - cell walls
gram + are thick and gram - are thin.
What is the name of the primary stain during staining?
Gram negative are what color after gram staining?
What is a wet mount of bacteria?
This is a liquid suspension of bacteria on a slide.
Should a lid be held at an angle over the plate when pouring media?
Name two different bacterial shapes.
Bacillis and Cocci
What grows with or without 02 but best in the presense of 02
Indicator strip that is placed in experiment to cultivate anaerobes?
Mesophile bacteria grow at what temp?
20 - 40
Obligate Anaerobic gather where in the tube
At the top
Thioglycolate broth prevents the diffusion of what from into the broth
O2 is toxic to this at atmospheric concentrations
Purpose and candle and air sealed jar in cultivating anaerobic bacteria in experiment.
Candle jar is for microaerophilic and brewers is for anaerobic.
Only grows without O2
anaerobic or strict anaerobes
MSA ferments salt names what to turn it from red to what color
MSA ferments mannitol salt to turn it from red to yellow
Thermophile bacteria grow at what temperature?
UV exposure causes what that can lead to mutations?
Between E.Coli and Bacilus, which would survive better at higher temperatures.
Bacilus would grow better because it has endospores which thrive at high temperatures.
Which plates are incubated upside down to prevent contamination?
Are microorganisms ubiquitous?
Yes. They can be found everywhere.
A wet mount lets us view what under a microscope
All solid media, gloves, and blunt disposable material need to be disposed of in the......
LB media are sterilized using
what bacteria appear violet after gram staining
Which bacteria have a thin peptidoglycan layer?
Which plate supports fungal growth?
Why is it impossible to stain the color to a bacterial capsule?
Because it is nonionic
Stains in order used during capsule staining?
Congo Red, Maneval Stain
Decolorizer in gram staining is what
How does capsule appear after performing a capsule stain
Colorless with a halo
Secondary stain in endospore staining is what
Endospores are produced by?
are gram (+), rod shaped, and produce endospores.
Which plates need to be incubated upside down?
BHI and TSA plates are bacterial plates, so they need to be incubated upside down, so condensation doesn't contaminate the medium.
Why use 1/2 strength TSA plates for culturing soil bacteria?
These plates reduce the population of microbes, so they are easier to visualize. There is also a more weedy population with full strength TSA plates.
Why flame when streaking?
This is so each new section has a smaller number of colonies, and we are able to isolate colonies in the later sections.
Purpose of Grams Iodine in Gram Staining?
Grams Iodine is used to set the stain in place, so it wont wash off when the acetone alcohol is used.
Importance of Heat Fixation of bacteria when preparing a smear on a slide?
This melts the outer membrane of bacteria, and helps to keep the bacteria stationary on the slide.
Nitrate and Nitrite
NO3- is nitrate and NO2- is nitrite Nitrate is reduced to nitrite by nitrate reductase then nitrite is reduced by nitrate reductase into either N2 or NH3
What is a bacteriophage?
A virus that is parasitic in bacteria; it uses the bacterium's machinery and energy to produce more phage until the bacterium is destroyed and phage is released to invade surrounding bacteria.
How to calculate PFU?
In terms of PFU per ml of solution
Plates use for bacterial contamination
Mac - # of gram (-) and # of lactose fermenters
MSA - # of gram (+) and # of mannitol fermenters
TSA - # of colonies
Why skin is inhospitable for bacteria?
Sebum (oil secreted from the skin) inhibits bacterial growth, and perspiration causes skin to be a hypertonic environment. Our normal flora is able to survive in these conditions.
Most common bacteria in nasal cavity?
staph a on MSA plate
Why do we did the peritoneal drop
Because dry skin from our anal area falls due to the upright position of our body, making it possible for fecal matter to be found on our leg/sock area.
Eosin Methylene Blue Agar
EMB is somewhat selective for gram (-) and when e.coli is grown on it, it appears a shiny metallic green color.
Main ingredients in beer
Hops, Yeast, Water, Malt
Ale vs Lager
Ale - hotter temps, fruity beer, "good Beer"
Lager- cooler temps, neutral beer, "bad Beer"
A playa is a low lying body of water that is made from water running off from a higher area.
gram negative, non-spore forming, rod that ferments lactose with gas formation. Found in fecal matter.
Water Quality Testing
measured in CFU/mL
EMB plates with coliforms
differentiate e.coli from other coliforms
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