Peptone

Peptone is a water-soluble mixture of peptides and amino acids obtained by the partial hydrolysis of proteins. It is widely used as a source of nitrogen and organic matter in microbial culture media and various biotechnological processes. Peptones are typically produced by hydrolyzing animal or plant proteins, such as casein from milk, gelatin from collagen, or soy proteins, using acid or enzymatic methods. The resulting hydrolysate is often filtered and dried to a powder or used as a liquid component.

In microbiology, peptones provide a readily utilizable nitrogen source and a supply of amino acids and short peptides that support the growth of bacteria, fungi, and other microorganisms. They are common components of complex media such as nutrient broth, nutrient agar, and tryptic soy broth, and are frequently combined with yeast extract or beef extract. The exact composition of a peptone varies by source and production method, which means many peptones are undefined mixtures; some products are more defined, representing hydrolysates from a single protein.

Common examples include tryptone (pancreatic digest of casein) and various plant-derived peptones such as soybean peptone. Peptones are typically sold as powders and are compatible with autoclaving. They should be stored in a cool, dry place. In addition to laboratory media, peptones are used in fermentation and certain enzymatic assays where a rich nitrogen source is required.

Safety considerations align with standard laboratory handling of biological reagents; commercial peptones are manufactured under hygienic conditions and are sterilized as appropriate.