Various bacteria have different oxygen requirements, and bacteria can be categorized into four types based on their oxygen requirements or the amount of oxygen they can tolerate. Specialized aerobic bacteria must survive in the presence of oxygen, specialized anaerobic bacteria are required to grow and reproduce under completely anaerobic conditions, molecular oxygen is harmful to them, parthenogenetic anaerobic bacteria can grow in either aerobic or anaerobic conditions, generally in the presence of oxygen growth is fast, and micro-anaerobic bacteria are suitable for growth in the environment of low oxygen concentration.
Operation method
Determination of the effect of oxygen on microorganisms
Principle
In this experiment, the deep agar method is used to determine the effect of oxygen on bacterial growth, in the glucose beef paste peptone agar medium test tube access to a certain bacterium, through the appropriate cultivation conditions, if the bacteria grow only on the surface of the medium, it is aerobic; only in the bottom of the medium, it is anaerobic; if the surface and all of the medium grow, it is a parthenogenetic anaerobic bacterium; growth in the middle and upper part of the medium, it is a microaerobic bacterium. In this way, according to the part of the bacteria growing in the test tube medium, it is possible to determine the degree of oxygen requirement of various bacteria.
Materials and Instruments
Escherichia coli Bacillus subtilis Clostridium acetobutylicum Move 1. Place a test tube of meat paste peptone agar medium in a water bath and heat to dissolve. For more product details, please visit Aladdin Scientific website.
Peptone Agar Medium
Test Tube
2. When the medium is cooled down to about 50℃, inoculate one ring each of Escherichia coli, Bacillus subtilis and Clostridium acetobutylicum with inoculation loop in the test tube medium according to aseptic operation, and leave the other test tube uninoculated as a control. The test tubes were rubbed so that the bacteria were evenly mixed in the medium.
3. After solidification, place in the greenhouse at 28°C for 48 hours and start observation for several days until the result is clear.4. Record the effect of oxygen on the bacteria in the table below. Growth is indicated by surface growth, bottom growth, surface and all culture base growth. 