Different types of well-known microbial metabolites map into the different chemical classes. For example, among the lipids, the "Steroids and steroid derivatives" class include the bile acids, sterol lipids, and cholesterol derivatives; short-chain fatty acids (SCFA) map into both the "Organic acids and derivatives" and "Fatty Acyls" (that include fatty acids) classes, depending on the size; fatty amides and long-chain fatty acids (LCFA) are both classified as "Fatty Acyls"; and glycerolipids, glycerophospholipids, and sphingolipids are classified in the same-name classes. As regarding non-lipidic molecules, both trimethylamine-N-oxide (TMAO) and polyamines map into the "Organic nitrogen compounds", while indole derivatives are classified in the "Organoheterocyclic compounds", and branched-chain amino acids and derivatives are assigned to the "Organic acids and derivatives" class, etc.