Difference b/w Gram Positive and Gram Negative Bacteria

Danish scientist Hans Christian Gram devised a method that allowed him to differentiate two types of bacteria based on their cell walls (gram-positive bacteria and gram-negative bacteria). Due to their structural differences, these two types of bacteria do not respond in the same way to antibodies, for this reason, it is important that we know the difference between one and the other; so that we can better understand what use each type can have or what it could cause. Difference b/w Gram Positive and Gram Negative Bacteria 

If you have doubts about the difference between gram negative and gram positive bacteria, keep reading, because we will explain to you below.

GRAM-POSITIVE BACTERIA Difference b/w Gram Positive and Gram Negative Bacteria 

They are those that are characterized by maintaining a violet or blue tint once the staining or Gram staining test is applied to them. This is due to the structure of its cell wall . Gram-positive ones do not have an outer cell membrane, instead they contain a large amount of peptidoglycan; which is responsible for maintaining the violet coloration.

Many gram-positive bacteria are non-pathogenic, that is, they do not cause disease; They are even part of the human commensal microbiomes found in the mouth, skin, gut, and respiratory tract. They are also a necessary ingredient in the production of some foods; as is the case with Swiss cheese.


On the other hand, when the aforementioned test is applied to them, gram- negative bacteria acquire a red or pink color. Unlike gram-positive ones, they do have an outer cell membrane.

Between 90-95% of gram-negative bacteria are pathogenic for humans, in addition, they are generally more resistant to antibiotics or develop resistance to them more quickly than gram-positive ones.

Finally, not all bacteria can be classified using the Gram test.

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