This gene controls the operator gene in cooperation with a chemical substance called inducer present in the cytoplasm. A regulator gene is not necessarily adjacent to the operator gene which it controls. The regulator gene codes for and produces a protein called repressor.
The Gram-positive bacteria include staphylococci (staph), streptococci (strep), pneumococci, and the bacterium responsible for diphtheria (Cornynebacterium diphtheriae) and anthrax (Bacillus anthracis). 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.
1. Gram positive bacteria: Stain dark purple due to retaining the primary dye called Crystal Violet in the cell wall. Example: Staphylococcus aureus. Fig: Gram positive bacteria. 2. Gram negative bacteria: Stain red or pink due to retaining the counter staining dye called Safranin.