Chemical structure of Bacteriovorax stolpii lipid A.

Bdellovibrionales is a phylogenetically diverse group of predatory prokaryotes, which consists of the two families Bdellovibrionaceae and Bacteriovoracaceae. We describe LPS and lipid A of the type strain Bacteriovorax stolpii DSM 12778, representing the first characterized endotoxin of a Bacteriovoracaceae member. It has a smooth form LPS, which was identified by SDS-polyacrylamide gel electrophoresis. The lipid A structure was determined by combined gas chromatography–mass spectrometry, electrospray ionization mass spectrometry and NMR spectroscopy. Its backbone consists of two β-(1 → 6)-linked 2,3-diamino-2,3-dideoxy-d-glucopyranoses (GlcpN3N) carrying a pyrophosphoethanolamine at O-4′ of the non-reducing sugar and a phosphate group linked to O-1 of the reducing GlcpN3N. Positions 2, 3, 2′ and 3′ of the two GlcpN3N are acylated with primary 3-hydroxy fatty acids and one of those carries a secondary fatty acid.