Experiments for the examination of microorganisms in the laboratory environment and on human surfaces facilitate (1) safety monitoring of microbiological levels in the laboratory (2) examination of pathogens.
Operation method
Experiments for the examination of microorganisms
Principle
The colony formed by each type of bacteria has its own characteristics, such as the size of the colony, the surface dry or wet, raised or flat, rough or smooth, the edges neat or untidy, the colony transparent or translucent or opaque, the color, and the texture sparse or compact. Thus, plate cultures can be used to examine the number and type of bacteria in the environment.
Materials and Instruments
Microorganisms Move 1. Writing labelsAny one of the experiments, in the hands-on before the need to first mark the vessel with a marker pen to do on the mark, the mark of the petri dish is generally written on the bottom of the dish. If written on the lid, while observing the results of more than two petri dishes, open the lid, easy to confuse. Write the class, name, date, and the source of the sample (e.g., laboratory air or sterile room air or hair, etc.) with a marker, and write it as small as possible on one side of the bottom of the dish, not in the middle of the dish, so as not to affect the results of the observation. Caveat 1. microorganisms are collected and are not contaminated by microorganisms from adjacent areas. 2. use sterilized utensils to collect specimens in sterile containers. 3. minimize the use of cotton swabs to transport specimens directly to the bacteriology room. 4. take care to avoid infecting others when collecting specimens. 4. take care to avoid infecting others when collecting specimens. Common Problems Dispose of your gloves after touching a toxic item with them. Whether or not you have been exposed to a toxic item, do not touch anything else indiscriminately with your gloves on, such as opening a window. For more product details, please visit Aladdin Scientific website.
Peptone Agar
Sterilized swabs Inoculation rings Test tube holders Alcohol lamps
2. Laboratory bacteriological tests
(1) Air Place one meat paste peptone agar plate in the laboratory where the experiment is being done at the time and remove the lid of the dish so as to expose the surface of the agar medium to the air; place the other meat paste peptone agar plate in a sterile room or other laboratory where no one is walking and remove the lid of the dish. After one hour cover both Petri dish lids.
(2) Knobs for lab tables and doors
① Use a marker to draw a straight line in the center of the outside of the bottom of the dish, and then draw a vertical line in the middle of this line.
② Removing the Cotton Swab Hold the test tube containing the cotton swab in your left hand and remove the cotton plug (or test tube cap) by holding it by the flame with the edge of the palm and the little and ring fingers of your right hand, passing the mouth of the tube very quickly through the flame of the gas lamp (or alcohol lamp) and cauterizing the mouth of the tube; gently tilt the test tube, and carefully remove the cotton swab with the thumb and forefinger of your right hand. Put back the cotton plug (or test tube cap) and place the empty test tube on the test tube rack.
③ Wet the cotton swab left hand to take the sterilized water test tube, as above method to pull out the cotton plug (or test tube cap) and cauterize the mouth of the tube, insert the cotton swab into the water, and then raise the water surface, in the wall of the tube to remove excess water, carefully remove the cotton swab, cauterize the mouth of the tube, put back the cotton plug (or test tube cap), and will be placed in the test tube rack of the sterilized water test tubes.
④ Sampling Wipe a wet cotton swab over an area of about 2 square centimeters on the lab bench or door knob.⑤ To inoculate, A makes the flat dish open into a slit with the left thumb and index or middle finger beside the flame. The swab is then inserted and inoculated at the top of the agar surface (rolled a little), and the lid of the dish is immediately closed. Remove the cotton plug (or test tube cap) from the empty test tube in which the swab was originally placed, cauterize the mouth of the tube, insert the used swab, and return the tube to the test tube rack.
(vi) Scribe another inoculation ring to be sterilized on the flame, first burn the end of the ring hot, then lift the inoculation ring and place it vertically on the flame to give the flame a wider contact with the wire, and when the inoculation ring burns red, then place the ring obliquely, and burn it upwards along the ring to the part where it may touch the Petri dish, and then move it to the end of the ring, and so on quickly passing it back and forth through the flame a number of times.
Pick up the plate in the left hand, again with a slit open, and pass the sterilized and cooled inoculation loop (you can test the temperature at the edge of the agar surface at the margin; if it makes a sputtering sound, it's too hot) through the inoculation zone at the top of the agar, and draw a line downward until halfway across the plate. Note: The angle of the inoculating ring to the surface of the agar should be small, and the pressure of movement should not be too great or the agar will be punctured.
Close the lid of the dish, turn the plate to the left with the left hand to the blank, and cauterize the inoculation ring held in the right hand again over the flame to make cold. The inoculation ring is passed through the line drawn earlier then over the other half of the agar, back and forth from top to bottom to the 1/2 way point.
Cauterize the inoculation ring, rotate the plate, scribe the last 1/4, immediately close the lid of the dish, cauterize the inoculation ring, and return it to its original position. The entire scribing operation requires asepsis, i.e., proximity to the flame and quick movement.
3. Screening for human bacteria
(1) Fingers (before and after hand washing)
(1) Label the two agar plates before and after handwashing (of course, class, name, and date items are essential in each label writing).
② Remove the lid of the dish and place an unwashed finger on the surface of the agar plate, gently scribe back and forth, and close the lid of the dish.
(iii) Using soap and a brush, brush hands vigorously, rinse well under running water, dry, move back and forth across the surface of another agar plate, and close the lid of the dish.
(2) Hair: On top of the agar plate with the lid removed, the hair is shaken vigorously several times by hand to land bacteria on the surface of the agar plate, and then the lid is closed.
(3) Coughing: Place the uncovered agar plate about 6-8 cm from the mouth, cough vigorously into the agar surface, and then cover the plate.
(4) Nasal
① Follow steps ② and ③ of the bench check method, remove the swab and wet it.
② Roll a wet cotton swab through the nose several times.
(iii) Inoculate and scribe according to steps ④ and ⑤ of the bench check method, and then cover the dish with a lid.
4. Turn all agar plates over so that the bottom of the dish is on top, place in a 37°C incubator and incubate for 1~2 days.
5. Methods of recording results
(1) Colony counting on a delineated plate, if the colonies are many and overlap, count the number of colonies in the last 1/4 area of the plate. Not the delineation of the plate, also divided into four, count the number of colonies in 1/4 area.
(2) Observe different colony types based on characteristics such as colony size, shape, height, wetness and dryness. However, it should be noted that if the number of bacteria is too large, it will cause many colonies to grow together, or limit the growth of the colony and become very small, thus the appearance is not typical, so when observing the characteristics of the colony, choose a single colony that is well separated.
The colony characterization method is as follows:
(1) Size large, medium, small, and pinpoint. A rough look at the colonies on the entire plate can be made before deciding on the criteria for large, medium, or small, or a range of sizes can be indicated by the teacher.
②Color yellow, golden yellow, gray, cream, red, pink, etc.
③ Wet and dry conditions dry, wet, sticky.
④Morphology round, irregular, etc.
⑤ Highly flattened, elevated, concave.
(vi) Degree of transparency transparent, translucent, opaque.
(vii) Neat and untidy edges.
6. Results
(1) Record the results of your own plate in the table below. 