Antibiotic whose production provides the bacterium a mechanism of host root nodule competitiveness with other invading inefficient strains. Sensitive to extremes of pH. Thermostable. Synthesized ribosomally as a prepeptide that is post-translationally modified to the active peptide. TfxB, TfxD and TfxF are all required for this processing. The chromophore is probably a six-membered ring derived from the cyclization of Gln-38. Maturation of thiazole and oxazole containing antibiotics involves the enzymatic condensation of a Cys, Ser or Thr with the alpha-carbonyl of the preceding amino acid to form a thioether or ether bond, then dehydration to form a double bond with the alpha-amino nitrogen. Thiazoline or oxazoline rings are dehydrogenated to form thiazole or oxazole rings.