Bacterial inoculation method selection and comparison

Bacterial inoculation method selection and comparison

There are many inoculation methods for bacteria, such as streak method, coating method, pouring method, slant inoculation method, liquid culture medium inoculation method, spiral inoculation method, etc. The methods and applications are different. The following explanations will help experimenters. Choose an action.

The streak method: This method is mainly used for the purification of strains to obtain a single colony.
Dip a little of the material to be separated from the inoculation loop, and perform parallel scribing, fan-shaped scribing or other forms of continuous scribing on the surface of the sterile plate. Now, if the streak is suitable, the microorganisms can be dispersed one by one, and after culturing, a single colony can be obtained on the surface of the plate.
Advantages: Colony characteristics can be observed and mixed bacteria can be separated.
Disadvantage: Cannot be used for colony counting.
 
Coating method: This method is mainly used for counting the total number of colonies
First melt the medium and pour it into a sterile plate while it is still hot, and then use a sterile pipette to draw 0.1 ml of the bacterial solution and inoculate it on the solidified agar plate. Then use a sterile L-shaped glass rod to smear the bacterial liquid on the plate evenly, lay the smeared plate flat on the table for 20-30 minutes, so that the bacterial liquid penetrates into the culture medium, then invert the plate, keep incubating for a long time. It can be counted after the bacteria are out.
Advantages: can be counted and colony characteristics can be observed.
Disadvantages: gradient dilution is required before inoculation, the absorption is less, which is more troublesome, the plate does not dry well, and it is easy to spread.

Dumping method: This method is mainly used for counting the total number of colonies
Add 1ml of bacterial liquid to the plate, pour the melted and cooled bacterial culture medium to 45~50°C, gently rotate the plate to mix the bacterial liquid and the medium evenly, invert after cooling, and cultivate at a suitable temperature. It can be counted after the colony has grown.
Advantages: can be counted, more convenient.
Disadvantages: gradient dilution is required before inoculation, colony characteristics cannot be observed, and it is not suitable for strict aerobic bacteria and heat-sensitive bacteria.
 
Slope inoculation method: This method is mainly used to preserve bacterial species, or to observe some biochemical characteristics and kinetics of bacteria
Use an inoculating loop or an inoculating needle to extend into the inoculation tube and pick out the colonies used for inoculation. Extend into the inclined culture tube, first drag an inoculation line from the bottom of the inclined surface to the top, and then meander the line from bottom to top, or directly meander from bottom to top. After the inoculation is completed, the mouth of the culture tube is sterilized with a flame, a cotton plug is plugged, and cultured at 37°C.
 
Liquid culture medium inoculation method: This method is mainly used for bacterial liquid turbidity experiments.
Pick colonies or specimens with a sterilized inoculation loop, and grind gently at the junction between the inner wall of the test tube and the liquid surface to make the bacteria evenly scattered in the liquid medium.