dye
(1) initial dyeing
Add a drop of ammonium oxalate crystal violet about 1min and wash it with water.
(2) mordant dyeing
Dropping iodine solution to wash off the residual water, dyeing for about 65438 0 minutes, and washing with water.
(3) Decolorization
Rinse off the water on the glass slide with white background, drip with 95% alcohol until the alcohol just doesn't appear purple, about 20-30 seconds, and immediately rinse off the alcohol with water.
(4) Double dyeing
Dye 1-2 minutes with saffron solution, and then wash with water.
(5) Microscopic examination
After drying, observe with an oil mirror. Gram-negative bacteria are red and Gram-positive bacteria are purple. Based on the Gram staining reaction of dispersed bacteria, too dense bacteria are often false positive.
(6) In the same way, Escherichia coli and Bacillus subtilis were mixed on the glass slide for Gram staining comparison.
Note: The dyeing time should be strictly controlled. The key is to strictly control the degree of alcohol decoloration. Excessive decoloration can mistakenly dye positive bacteria into negative bacteria. When decolorization is not enough, negative bacteria can be mistakenly dyed as positive bacteria. In addition, the age of bacteria also affects the staining results. For example, positive bacteria have been cultured for too long, or have died, and some bacteria dissolve on their own, which is often negative.