Microbiology Lab Exam 1
When should you sterilize your loop?
Before and after use through Bunsen burner if BSL-1 or in enclosed electric incinerator if BSL-2 (also, sterile disposable loops/wooden sticks)
When should inoculating instruments be flame sterilized?
Before and after you transfer the culture
Why is autoclaving rather than boiling water used for sterilization?
Boiling water does not kill everything, including bacterial endospores and some protozoan cysts. Boiling water reaches a maximum temperature of 100 degrees Celsius, compared with autoclaving where the temperature reaches at least 121 degrees Celsius. Boiling water is not hot enough to kill endospores or cysts in a reasonable amount of time.
Which property of the lens describes its ability to show two adjacent objects as discrete entities?
Resolving power
Basic stain-
Stain with a positively charged chromogen
Which of the following is an INCORRECT association? -Resolving power; expressed mathematically as a function of the wavelength of light and the numerical aperture -Magnification; degree of enlargement of the specimen when using a specific lens or combination of lenses -Iris diaphragm; used to raise and lower the objective lenses to bring the specimen into focus -Stage; platform with an opening in the center that allows for the passage of light through the specimen
-Iris diaphragm; used to raise and lower the objective lenses to bring the specimen into focus
What is the correct order of loop sterilization? 6 steps
1) Attach burner to gas source. Adjust air intake 2) Turn on gas 3) Light burner with striker 4) Adjust air supply 5) Heat loop until entire wire glows red 6) Cool loop
Steps for preparing a smear from a broth culture:
1) Flame loop & cool. Suspend broth culture. 2) Remove cap & pass tube through flame 3) Obtain loopful of culture from tube 4) Pass mouth of tube through flame & re-cap 5) Spread culture on slide. Let air-dry 6) Flame loop
Imagine you're streaking a plate. You've just finished the first streak (streak a), closed the lid, and rotated the plate. Arrange the next steps of the procedure in their correct order.
1) Flame loop and let cool 2) Lift lid of petri plate 3) Streak across streak a and into Quadrant 2 4) Streak within Quadrant 2 5) Close petri plate lid 6) Rotate plate and flame loop
Describe appropriate attire that should be worn in lab:
1) Wear eye protection whenever heating chemicals 2)Wear disposable gloves while staining microbes and handling blood products 3) Lab coat 4) close-toed toes
Describe 2 specialized waste containers that can be found in lab:
1) sharps/broken glass container: disposal of broken glass or any other item that could puncture an autoclave bag 2)autoclave container: disposal of plate cultures and other contaminated non-sharp disposable items
What is the correct sequence for performing a direct stain on microbes from a liquid culture?
1) spread cells on slide 2) air-dry 3) heat-fix 4) add stain rinse 5) blot
It has been determined that the temperature in an autoclave should reach __________ for sterilization.
121 degrees Celsius (and 15 psi for 15 minutes to sterilize small volumes) (
Which of the following are the parameters for autoclaving?
15 minutes at 121°C and15 psi
Which of the following is the correct sequence for the aseptic transfer of a microbial inoculum?1) Remove the cap from the culture tube. 2) Reheat the mouth of the culture tube and replace the cap. 3) Get a loopful of the culture. 4) Sterilize the loop by heating it red-hot. 5) Flame the mouth of the culture tube.
4-Sterilize the loop by heating it red-hot 1- Remove the cap from the culture tube 5- Flame the mouth of the culture tube. 3- Get a loopful of the culture 2- Reheat the mouth of the culture tube and replace the cap
A scientist is using an objective lens with 40X magnification on his microscope. If the ocular lens magnifies 10X, what is the total magnification being used to visualize the specimen?
400X
Once you have sterilized your inoculating loop, it is important that you wait 10-20 seconds before using the loop to pick up a sample from your culture. What is the purpose of letting the inoculating instrument cool off?
Avoid killing the bacterial cells with excess heat
Which of the following statements is true regarding proper aseptic culturing techniques? A) It is necessary to hold the inoculating instrument in the Bunsen burner flame until it becomes red hot. B) Blow gently on the sterilized inoculating loop to make sure it is cool enough to pick up the culture. C) After removing the cap of the culture tube, place the cap onto the bench top to prevent contamination. D) All of the above
A) It is necessary to hold the inoculating instrument in the Bunsen burner flame until it becomes red hot.
Which component of the microscope is found directly under the stage, and contains two sets of lenses that collect and concentrate light as it passes upward from the light source into the lens systems?
Abbe condenser
Where should you label your Petri plate with information about the culture?
All labeling should be done on the bottom portion of the agar plate. This ensures that the written information stays with your culture, even if the lid gets accidentally exchanged with another plate.
It is necessary to dilute the bacterial inoculum when transferring from what type of culture media?
Any solid (agar-based) media
Why is a specimen smaller than 200 nm not visible with a light microscope?
Anything smaller than 200 nm cannot interact with visible light
Transfer to an agar deep involves a slightly different procedure from transfer to an agar slant. Which of the following steps is unique to inoculating an agar deep? A) Two loopfuls of inoculum must be transferred. B) An inoculating needle is used to stab the inoculum into the agar. C) The agar deep medium must be heated (melted) so that it is liquid when inoculated. D) The inoculum must be taken from a broth culture.
B) An inoculating needle is used to stab the inoculum into the agar. An inoculating needle is used for inoculating an agar deep. The agar deep medium is stabbed, not streaked. This technique is used in some biochemical tests to place the bacteria within the medium, rather than on the surface.
Smear preparation from a slant culture differs from smear preparation from a broth culture in what way?
Bacteria from a slant culture must be mixed with a loopful of water Because the slant culture is solid, not liquid, water is required to make the smear a uniform thickness.
Why are basic stains attracted to the bacteria itself?
Cell wall components carry a negative charge and the chromogen has a positive charge; opposite charges attract one another.
If you are unable to get your bacterial slide to focus using the 10X objective lens, but it was focused with the 4X lens, what would be the first thing to try?
Clean the 10X lens
Why must electronic devices and other personal items be put away before entering the lab room and not brought out before fully exiting the room?
Contamination of these items can be a health hazard as well as expensive.
What is the protocol if infectious material is spilled?
Cover any culture spills with paper towels. Soak the towels immediately with disinfectant and allow them to stand for 20 minutes. Report spill to the instructor. When you are finished, place towels in container for autoclaving
You notice that extended use of the microscope is giving you a headache. Your professor mentions that the headaches may be due to staring into light that is too bright for extended periods of time. What should you do the next time you use a microscope to reduce your chances of another headache?
Decrease the amount of light using the iris diaphragm lever
What is the purpose of allowing the bacterial smear to dry once it has been placed onto the surface of the slide?
Drying helps remove excess water to ensure optimal heat fixation.
If a correctly streaked plate were INCORRECTLY incubated right side up (instead of upside down), which of the following plate results would you most likely see?
During incubation, water tends to condense in the lid of Petri plates. If the plate is incubated in a right-side-up position, this condensation will "rain" onto the surface of the agar. The water on the agar will create a soupy mess of bacteria instead of isolated colonies. Incubating the plate upside down keeps water condensation in the lid and away from your culture.
Why are endospores used to measure the effectiveness of autoclave sterilization?
Endospores are very hard to kill
A positively charged chromophore will NOT stain cells.
False
Environmental bacteria or fungi will not affect your results when culturing microorganisms.
False
The growth characteristics of a bacterial culture streak on an agar slant will not be the same as if the streak were on an agar plate.
False
You should always put oil on the slide before you try to get it into focus at low magnification.
False
Visual inspection of a broth culture after 24 hours of growth will indicate whether it was incorrectly transferred using non-aseptic techniques and is now contaminated.
False A microscope is needed to differentiate between bacterial species.
After you've removed a loopful of broth culture from the culture tube, what's your next step in preparing a smear?
Flame the opening of the tube You should flame the mouth of the test tube before and immediately after removing a loopful of culture, as shown in this video. This helps prevent airborne contaminants from entering the culture.
Why should you flame the mouth of a tube?
Flaming the mouth of the tube prevents airborne bacteria from entering the tube while it is uncapped. Airborne bacteria may fall anywhere on this slant and grow to form a colony.
You're preparing a smear from a broth culture. You've labeled a clean slide. You've flamed the inoculating loop and let it cool. What's your next step?
Flick the culture tube In preparing a smear from broth, you want to be sure enough cells make it onto your smear. Cells in broth cultures tend to settle to the bottom of the tube. This leaves very few cells in the top layer, where you'll be inserting the loop. Flicking the tube resuspends the cells evenly in the broth.
A student is observing a stained smear that was prepared from a slant culture. This micrograph shows what was observed. Assuming he placed culture on the slide during preparation of the smear, which of these errors most likely explains the observed result? (Slide shows few microbes)
He forgot to fix the slide One of the purposes of fixation is to make the cells stick to the slide. If the student had forgotten to fix the slide, the cells probably washed off during the staining procedure.
What's the purpose of heat fixation?
Heat fixation adheres the cells to the slide and coagulates the bacterial proteins, effectively killing the bacteria.
Which of the following objective lenses is the ONLY lens that should be used with oil immersion?
High-power lens (100X)
Why do containers of liquid placed in an autoclave need to remain at least slightly open?
If they remain closed, they may implode. The extreme temperature and pressure changes within the autoclave may cause closed containers to implode.
Why is it important not to use thick or dense bacterial smears?
In a thick smear the bacteria will be too concentrated, reducing the amount of light passing through the slide, the stain may not penetrate adequately, and it will be difficult to visualize individual cells.
Microorganisms are typically present in which of the following locations? -On laboratory surfaces -In the air -On your skin -In the air, on laboratory surfaces, and on your skin
In the air, on laboratory surfaces, and on your skin
Which of the following microscope parts should routinely be adjusted to control the light source and provide optimal illumination of the specimen?
Iris diaphragm
Which of the following observations would suggest that a plate was inoculated with a pure (axenic) culture? -Isolated colonies are all white in color and about the same size. -Isolated colonies are all white in color, but some colonies are noticeably larger than others. -Bacterial growth is apparent in all four quadrants. -Bacterial growth is apparent along the streaks connecting each quadrant.
Isolated colonies are all white in color and about the same size. Bacterial species tend to produce distinctive-looking colonies. If all colonies on the plate appear identical, then it's likely the inoculum was pure.
Why must Bunsen burners and incinerators be treated with caution even after you have finished using them?
It is a fire & safety hazard as well as an additional source of unnecessary heat in the room
What is meant by light rays being divergent?
It is spreading out
Which one of the following is FALSE about a simple, direct stain? -It colors the cells. -It usually involves a basic stain. -It uses one stain. -It is used to determine morphology. -It uses a negatively charged chromophore.
It uses a negatively charged chromophore.
What is the role of lenses in microscopy?
Lenses focus either light or electrons to create a magnified image of a specimen.
Which of the following is an example of a basic stain? -Methylene blue -Ethyl alcohol -Nigrosin -India ink
Methylene blue
How can you improve a smear?
Obtain a smaller amount of culture for the smear When making a smear from a solid culture, you need only a tiny amount of bacteria. If you obtain too much culture, the cells will appear crowded, making their arrangement difficult to determine. Note the difference in this micrograph of a smear that was prepared using a much smaller amount of culture.
Loss of bent, or refracted, light results in a reduced numerical aperture, which diminishes the resolving power of the objective lens. Adding which of the following substances between the slide and the lens acts to decrease the refraction of light?
Oil
Which of the following describes a proper fixation technique?
Pass the slide 2 or 3 times through the flame This method gently heats the slide, which denatures the proteins within the bacteria. Much like frying an egg, this causes the bacteria to become more rigid, preserving their natural shape. It also causes the bacteria to adhere to the glass slide
During heat fixation, it is important that the slide be passed only 2-3 times through the outer portion of the Bunsen burner flame to prevent overheating. Overheating can cause which of the following to occur?
Plasmolysis of the bacterial cell wall, distorting the cell morphology
What role does pressure play in an autoclave?
Pressure is applied to boiling water to prevent heat from escaping as steam (Adding pressure to boiling water leads to higher water temperatures.)
What is the difference between spirilla and spirochetes?
Spirilla are rigid, while spirochetes are flexible.
Under which of the following conditions would you be most likely to prepare (and use) a smear? -Isolating individual bacterial species from a mixed culture. -Transferring bacteria from a broth culture to a slant tube. -Staining bacterial cells to observe under the microscope. -Determining whether bacteria can break down a particular nutrient.
Staining bacterial cells to observe under the microscope Smears are prepared by spreading bacteria on a microscope slide. Once the sample is spread out and stained, the characteristic shape and arrangement of the bacteria can be seen under the microscope.
Which of the following is the proper technique for inoculating an agar slant? -Streak the surface of the media with a back-and-forth motion using an inoculating loop. -Streak the surface of the media with an inoculating needle. -Stab the butt of the tube using an inoculating needle. -Stab the butt of the tube using an inoculating loop. Stab the butt of the media with glass rod.
Streak the surface of the media with a back-and-forth motion using an inoculating loop.
Why is the technique of subculturing an important one that a microbiologist should master?
Subculturing allows microbiologists to inoculate multiple tubes, broths, and agar plates, which helps them identify and characterize microorganisms in a laboratory setting.
A student prepares a smear from a broth culture; air-dries it, and fixes it. He then remembers that he forgot to flick the broth culture tube before removing the bacteria. What is the most likely consequence of this error?
The bacteria may be difficult to find on the slide. Broth cultures should be resuspended so that bacteria are evenly distributed throughout the broth. Otherwise, you could end up with very few bacteria in the smear. With very few bacteria in the smear, finding bacteria will be difficult. You'll waste a lot of time searching.
What is an inoculum?
The bacteria transferred to a new medium. The bacteria that are transferred during inoculation are called the inoculum. The new sterile medium receives, or is inoculated with, the inoculum. The inoculum, it is hoped, consists only of the desired species of bacteria and does not include any contaminants.
Why does the presence of grease or dirt on a glass slide result in a poor smear preparation?
The grease and dirt can create artifacts that interfere with accurate visualization of the organisms.
A student properly flames her loop but then forgets to let it cool. Instead, she immediately inserts the hot loop into her broth culture. What is the most important issue associated with this mistake?
The hot loop may create aerosols when it touches the culture When the hot loop touches the liquid broth culture, it will cause some of the broth (and bacteria) to boil briefly, creating a bacteria-containing aerosol. These airborne bacteria could enter the student's respiratory tract or land on her skin. If you hear a hissing sound when you place the loop into the broth culture, you'll know you haven't cooled the loop sufficiently.
A student properly flames her loop but then forgets to let it cool. Instead, she immediately inserts the hot loop into her broth culture. What is the most important issue associated with this mistake?
The hot loop may create aerosols when it touches the culture. When the hot loop touches the liquid broth culture, it will cause some of the broth (and bacteria) to briefly boil, creating a bacteria-containing aerosol. These airborne bacteria could enter the student's respiratory tract or land on her skin.
Which hypothesis best explains why there is so little growth on the agar?
The loop dug into the agar during inoculation. Notice the small gouge in the agar at the bottom of the slant, as indicated by the arrow in this photograph. The student most likely gouged the agar with the loop, depositing a good portion of the inoculating cells under the surface of the agar. After the gouge, very few cells were left on the loop to inoculate the rest of the slant surface.
If a student forgets to flame the mouth of a broth culture tube before transferring culture to it, what might result?
The medium in the tube might become contaminated. Heating the mouth of the test tube creates an air current that helps prevents airborne bacteria from falling into the tube while the tube's cap is off. If airborne bacteria do fall into the tube, they will contaminate the medium.
What could occur if, during a streak-plate inoculation, your loop went into the area of the first introduction of the bacterial culture and then into the final area?
The number of bacteria in the final area would be increased so much as to negate any dilution effects.
In a typical brightfield microscope (seen in the animation), at which point does magnification begin?
The objective lens
How would you know that the unknown culture contains two species of bacteria?
There are multiple distinct colonies along the streak lines consistently in each quadrant. This suggests that more than one microbe was present in the initial inoculum.
What happens to the light rays when they hit the specimen?
They are reflected, refracted, or absorbed by the specimen.
Why are endospores sometimes used in sterility indicators?
They are the hardest life form to kill. If an autoclave kills endospores within a sterility indicator, it is safe to assume that everything else is sterilized.
How do scientists ensure that autoclaved materials were actually sterilized?
They may place a sterility indicator with a special dye to detect the growth of endospores. ( Some sterility indicators have dyes that change color in the presence of living bacteria, indicating that the correct sterilizing temperature and time have not been reached.)
What is the role of the ocular lens?
To recreate the image in the viewer's eye
What's wrong with placing the cap from the tube on the bench top?
This may have contaminated the cap. Once the cap is placed back on the tube, the bacteria on the cap may contaminate the culture within the tube. Always hold caps in the hand that holds the loop. This minimizes the chance that environmental microbes might contaminate the cap.
Why would there be colonies on this plate that have different color, size, and shapes?
This means that another bacterial species is present—a contaminant. Notice, too, that both colonies are growing along the streak lines. This suggests that both species came from the broth tube. Airborne contaminants introduced during streaking would, in contrast, be more randomly scattered about the plate.E. coli colonies should all have the same color, size, shape, and margins.
Why should the lid should partially cover the plate while the student is removing inoculum?
This technique prevents airborne microbes from contaminating the surface of the agar.
Why must both the wire and the loop portions of the inoculating loop must be heated until red-hot?
To be properly sterilized The nonglowing wire could still contain live bacteria that might contaminate the student's cultures.
Which of the following best describes aseptic technique?
To manipulate bacteria without introducing contaminants. Aseptic technique is used to prevent environmental bacteria (e.g., from the air) from contaminating cultures. This is why we flame the mouths of the culture tubes before and after transferring bacteria.
What is the purpose of applying a stain to a bacterial smear?
To provide contrast between the organism and the background.
Imagine that you forgot to flame the loop before streaking the inoculum from the first quadrant into the second quadrant. What is the most likely consequence of this error?
Too much bacterial growth outside the first quadrant. Proper streak plating technique deposits progressively smaller amounts of bacteria in each quadrant. This is done by having the loop pick up only a small amount of bacteria from the previous quadrant's streaks. Flaming the loop between streaks ensures that the loop starts clean and that only this small amount of bacteria is used to inoculate the next quadrant.
After flaming the loop or the needle to sterilize it, you will need to allow it to cool for a few seconds so that the heat will not kill or damage the bacteria you are about to pick up with it out of the broth culture.
True
If you are transferring bacteria from a broth culture to multiple tubes of different broths and agar types you should always flame the loop after transferring into each new tube.
True
If you aseptically transferred a single colony from a streak plate to a test tube with a broth-growing medium, all of the bacteria in that broth would be genetically identical.
True
In general, moist heat kills microorganisms in less time than dry heat.
True
Normal microbiota may cause disease if conditions change in the body.
True
The growth resulting in the elevation of a bacterial colony is due to the colony growth spreading vertically as well as horizontally.
True
When looking at a blood agar plate with bacterial growth, beta is complete lysis of the red blood cells, alpha is partial lysis, and gamma is no lysis.
True
When should hands be washed?
Wash your hands thoroughly with soap and water after handling living microbes and before leaving the laboratory each day. Also, wash your hands after removing gloves.
What would a streak plate look like if you had not sterilized the loop between streaking into the new areas of the plate?
While the number of bacteria colonies seen in each area may decrease, the numbers would not decrease enough for individual colonies to form.
How do you clean your lab bench?
Wipe the desktop with a disinfectant (e.g., Coverage or 10% chlorine bleach) before and after each lab period. Allow disinfectant to evaporate; do not wipe dry
Why is it important to flame the loop between quadrant streaks?
You want to spread only a tiny fraction of the bacteria in one quadrant to the next, so it's important to flame and cool the loop between each streaking step. This ensures thinning of the bacteria with each streak, which ultimately produces isolated colonies after incubation.
Which of the following techniques can be used to sterilize microbiological media?
autoclaving
Which of the following techniques is NOT used to isolate bacteria and develop a pure culture? -pour-plate technique -spread-plate technique -a mixed broth culture tube -streak-plate technique -None of the listed responses is correct.
a mixed broth culture tube
A colony on an agar plate that is slightly and equally elevated and unbroken would be classified as ___________________
a raised, circular colony.
A reservoir is
a source of microbial contamination.
To solidify media used to grow microbes, usually __________ is added to the nutrient broth.
agar
The main advantage of a spread plate over a streak plate is that the spread plate __________.
allows for the calculation of cell numbers
A pathogen is best described as
any microorganism that causes disease.
To prevent or minimize contamination, __________ is used in microbiology procedure.
aseptic technique
Which of the following lists microbes or microbial structures in order from the hardest to destroy by heat to the easiest to destroy? (4 total)
bacterial endospores, fungal spores, vegetative bacteria, fungi
Sterilize your loop __________.
before and after transferring bacteria
A loopful of water is placed on a slide __________.
before bacteria are transferred from a solid medium
Aseptic techniques used in microbiology involve all the following EXCEPT __________. -heating the mouth of the culture tube -blowing on your loop to cool it -heating the inoculating loop -disinfecting the work area -holding culture tubes at an angle
blowing on your loop to cool it
Which of the following media would NOT contain agar? -semisolid deep -broths -solid deep -Petri plates -slants
broths
Staphylococcus bacteria are commonly present in the human nasal cavity but rarely cause disease of the upper respiratory system. This situation is an example of (commensalism/mutualism/parasitism).
commensalism
The purpose of the microscope condenser is to ______
collect and concentrate light
An unwanted organism in a streak plate is called a(n) __________.
contaminant
Unwanted microbes that find their way into our cultures are called
contaminants
Vibrio cholera is a water-borne pathogen that colonizes the gastrointestinal tract. How would you describe the shape of this organism?
curved rod
In the streak-plate method, streaking the bacteria from region to region on the Petri dish serves the purpose of __________.
decreasing the numbers of bacteria in each area, producing individual colonies in the final area
In the streak-plate technique, the intent is to isolate bacteria by dilution in theory by __________.
dilution on a solid surface
What step did you forget if you see moving bacteria in your stained preparation?
fixing
he cultural characteristics of a bacterial colony are almost entirely due to __________
genetic factors affecting growth patterns
Before you use an inoculating loop or needle, it must be __________.
heated until red-hot
Where are you likely to find an autoclave?
in a dentist office
Where should gloves be disposed of? Why?
in container designated for autoclaving/biohazardous waste bin to reduce risk of contamination
Bacteria are routinely __________ into new culture media to study their growth and other characteristics.
inoculated
Streak plates are useful in microbiology to __________.
isolate bacteria and develop pure cultures
Why should you lift the lid of the Petri plate only enough to get the loop inside?
keeps the agar protected and prevents airborne microbes from falling into your culture.
The use of clean lenses increases the efficiency of the microscope. While dry lenses should be cleaned with _____, the oil-immersion lens can be cleaned with _____, followed by 95% ethanol.
lens paper; xylol
How should you heat an inoculating loop in the Bunsen burner flame to ensure sterility?
loop and wire until they become red hot
An inoculating _____ is generally used to obtain an inoculum from a broth culture, while an inoculating _____ is typically used to transfer microorganisms to an agar deep tube.
loop; needle
A compound microscope uses two lenses at once to magnify the image of a specimen. The _____ lens is found in the eyepiece and the _____ lens is found in the revolving nosepiece.
ocular; objective
Commensalism is best described as a(n)
relationship between two organisms where only one member benefits and the other is unharmed.
An organism that obtains its nutrients from dead organic matter is a(n) __________.
saprophyte
What two characteristics are used to describe the cellular morphology of a microscopic organism?
shape and arrangement
An air-dried preparation of bacteria on a slide is called a __________.
smear
Since most bacteria are colorless, __________ makes them easier to see under the microscope.
staining
For a plate to be streaked correctly...
streak d must draw inoculum from streak c. In this example, streak d draws inoculum from streak a instead. This will draw too much bacteria into quadrant 4 and produce few, if any, isolated colonies.
Which of the following isolation techniques does NOT require the preparation of sterile dilution buffer? -pour-plate -streak-plate -spread-plate -All of the listed techniques require sterile dilution buffer. -None of the listed techniques require sterile dilution buffer.
streak-plate
The lysis of red blood cells in blood agar is indicative of the presence of which enzymes?
streptolysin O and S
The process of transferring microorganisms from one medium to another is known as:
subculturing
Which of the following could NOT be easily determined using a simple direct stain? -the Gram reaction of the cells -the arrangement of the cells -the shape of the cells -the relative size of the cells
the Gram reaction of the cells
What happens when a plate is exposed to airborne contaminants?
the contaminating microbes settle all over the plate. After incubation, the colonies from these contaminants will be all over the plate also, not just following the streak lines.You want to spread only a tiny fraction of the bacteria in one quadrant to the next, so it's important to flame and cool the loop between each streaking step. This ensures thinning of the bacteria with each streak, which ultimately produces isolated colonies after incubation
What is the purpose of an autoclave?
to sterilize equipment and media Autoclaves are used to ensure that equipment and media are sterile, or free of contamination
A nutrient agar slant is used in microbiology to __________.
transport and store microbes
A streak plate would work best to isolate bacteria if ____________________
you think there may be a chance of a contaminate in your broth culture.
