The chemical reactions and pathways resulting in the formation of a fatty acid, any of the aliphatic monocarboxylic acids that can be liberated by hydrolysis from naturally occurring fats and oils. Fatty acids are predominantly straight-chain acids of 4 to 24 carbon atoms, which may be saturated or unsaturated; branched fatty acids and hydroxy fatty acids also occur, and very long chain acids of over 30 carbons are found in waxes.

The chemical reactions and pathways resulting in the formation of lipid A, the glycolipid group of bacterial lipopolysaccharides, consisting of four to six fatty acyl chains linked to two glucosamine residues. Further modifications of the backbone are common.

The process in which single-celled organisms monitor their population density by detecting the concentration of small, diffusible signal molecules produced by the cells themselves.

The chemical reactions and pathways resulting in the formation of siderophores, low molecular weight Fe(III)-chelating substances made by aerobic or facultatively anaerobic bacteria, especially when growing under iron deficient conditions. The complexes of Fe(3+)-siderophores have very high stability constants and are taken up by specific transport systems by microorganisms; the subsequent release of iron requires enzymatic action.