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

Difference Between Gram-Positive and Gram-Negative Bacillus Written by WebMD Editorial Contributors Medically Reviewed by Sabrina Felson, MD on April 27, 2025 ...

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.

Numbers of 0.92 or -0.97 would show a strong positive and negative correlation respectively. Negative Correlation. Image by Sabrina Jiang © Investopedia 2021.