When it is removed the amino group becomes an ammonia molecule. The ability of a bacterium to deaminate phenyalanine is a common assay used in identification of intestinal bacteria. The -COOH group is the carboxyl group. The ability of a bacterium to remove the carboxyl group of arginine, lysine, and ornithine is an important assay in identification of intestinal bacteria. Biochemists use the suffix -in to designate proteins.
Peptones are soluble pieces cut from proteins.
Since gelatin is a fairly pure and cheap protein, it is useful for testing the abililty of bacteria to digest a particular protein. There are lots of proteins around the home that you can use use high protein media. Some of those used by professionals are meat, brain, egg, liver, gelatin, can add to TGY and other bases. Skim milk contains the disaccharide lactose and two protein complexes and is a useful medium covered on page b028 . Until I get this page completed, keep in mind you can use a meat grinder to grind any meat, soak the ground meat in water,and then boil it to produce and infusion broth as we did on page b022 to make Easy Broth.