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.
Gram-negative bacteria are a group of bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall sandwiched between an inner cytoplasmic cell membrane and a bacterial outer membrane.