Final answer:
Non-canonical amino acids (NCAAs) are compounds that are not true proteins but contain nitrogen and can be used by bacteria to make bacterial proteins through direct feeding to auxotrophs or metabolic engineering.
Step-by-step explanation:
The compounds that are being referred to are generally known as non-canoncial amino acids (NCAAs), which are not true proteins by nature but contain nitrogen and can be used by bacteria to synthesize bacterial proteins.
These NCAAs can be introduced into organisms through direct feeding to auxotrophs, or via metabolic engineering, wherein organisms are supplied with NCAA precursors. These techniques allow for the proteome-wide incorporation of unnatural amino acids into proteins, which can serve various purposes in research and industrial applications.