Gram-positive:Gram-positive细菌retain the color of the crystal violet stainintheGram stain. This is characteristic of bacteria that have acellwall composed of a thick layer of a particularsubstance(called peptidologlycan).
TheGram-positive细菌include staphylococci ("staph"), streptococci ("strep"), pneumococci, and thebacteriumresponsible for diphtheria (Cornynebacterium diphtheriae) and anthrax (炭疽杆菌).
The Danish bacteriologist J.M.C. Gram (1853-1938) devised a method of staining bacteria using a dye called crystal (gentian) violet. Gram's method helps distinguish between different types of bacteria. The gram-staining characteristics of bacteria are denoted as positive or negative, depending upon whether the bacteria take up and retain the crystal violet stain or not.
