Formation of halogenated aryl-polyene (Xanthomonadin) pigments by the type and other yellow-pigmented strains of Xanthomonas maltophilia

Abstract

Based upon visible electronic absorption spectra and mass spectra, yellow-pigmented strains of Xanthomonas maltophilia, including the type strain (ICPB 2648-67 = ATCC 13637) of this species, were shown to produce aryl-polyene (xanthomonadin) pigments. These pigments, which usually occurred in very small quantities, were isolated and studied as isobutyl derivatives. The most common X. maltophilia pigment (Pigment 1), which occurred in 8 of the 12 yellow-pigmented strains examined, was shown to be a monochlorinated aryl-hexaene, molecular ion (M+) 384, with the empirical formula C23H25O3Cl. Pigment 3, M+ 376, which was found as the major pigment in one strain of X. maltophilia and as a minor component in two other strains, probably is the same non-halogenated aryl-heptaene reported previously in Xanthomonas populi and X. juglandis. Although all of these X. maltophilia strains originated from medical rather than phytopathogenic environments, the occurrence of these xanthomonadin pigments in non-phytopathogenic strains emphasizes the chemotaxonomic significance of these aryl-polyene pigments in the genus Xanthomonas.