Most species of bacteria can be broadly divided into two groups, known as gram-positive and gram-negative. These categories ...

Gram-positive bacteria show blue or purple after Gram-staining in a laboratory test. They have thick cell walls. Gram-negative bacteria show pink or red on staining and have thin walls.

In gram positive bacteria, the large crystal violet-iodine complexes are then unable to penetrate and escape the thick peptidoglycan layer, resulting in purple stained cells. However, in gram negative ...

If the peptidoglycan layer is thin, it's classified as gram negative. Characteristics of Gram-Positive Bacilli. A gram-positive bacillus doesn't have an outer cell wall beyond the peptidoglycan ...