There are many ways of classifying bacteria. One method is based on the cell membrane. In 1884, a bacteriologist named Christian Gram created a test that could determine if a bacterium had a thick, ...

Gram-positive bacteria have thick cell walls. A Gram stain test, which involves a chemical dye, stains the bacterium’s cell wall purple. On the other hand, gram-negative bacteria stain pink instead.

Mouths are filthy, harboring the second largest microbiome of the human body. Some bacteria can help break down food, among other responsibilities; other bacteria can travel into the mouth on food, ...

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. They release ...