The carbon source and nitrogen source of McConkey agar
McConkey agar, its carbon source mainly contains lactose. As a disaccharide, lactose can provide energy and carbon skeleton for microbial growth. During the process of metabolizing lactose, microorganisms decompose it through a series of enzymatic reactions, and then obtain the carbon elements required for growth.

As for the nitrogen source, McConkey agar contains peptones. Peptones are obtained by protease hydrolysis of proteins and are rich in a variety of amino acids. These amino acids not only provide nitrogen for microorganisms to build cell structures, but also are used to synthesize nitrogen-containing biological macromolecules such as proteins and nucleic acids, and also participate in various physiological activities during microbial metabolism. Microorganisms use the nitrogen source in peptones to convert them into their own substances through complex metabolic pathways to meet the needs of growth and reproduction.

Thus, lactose and peptone, as important carbon and nitrogen sources of Maconquay agar, jointly supported the growth and metabolism of specific microorganisms on the medium.