These expensive tryptones are often used in diagnostic media when super clarity is needed. Some tryptones are much cheaper and form quite turbid, darker colored solutions with some sediment and often support better growth of microbes. These are commonly used in manufacteuring antibiotics and other drugs. Phytone is a tryptic digest of soybean proteins. Some bacteria isolated from plants may grow a little better on phytones than on tryptones.
Peptones are enzymic digests of other proteins often meat scraps.
Minerals Oxygen Nitrates as honorary oxygen. Vitamins Yeast Extract Yeast extract is used in most media for microbes from plants and animals. Some of these microbes require vitamins and other growth factors from their plant or animal hosts and yeast extract is rich in vitamins, minerals, and digested nucleic acids. However, yeast extract is very hydroscopic and is difficult to keep dry in the classroom and is sometimes difficult for students to obtain. See YIB on page b030 for a method for making your own yeast extract.