CHARACTERIZATION OF LIPOPOLYSACCHARIDE-DEFICIENT MUTANTS OF PSEUDOMONAS-AERUGINOSA DERIVED FROM SEROTYPE-O3, SEROTYPE-O5, AND SEROTYPE-O6

Well-characterized rough mutants are important for the understanding o f structures, functions, and biosynthesis of lipopolysaccharide (LPS) in gram-negative organisms. In this study, three series of Pseudomonas aeruginosa LPS-deficient mutants, namely PAC strains derived from ser otype O3, AK strains derived from strain PAO1 (serotype O5), and serot ype O6-derived mutants were subjected to biochemical analysis by sodiu m dodecyl sulfate-polyacrylamide gel electrophoresis and silver staini ng as well as immunochemical characterization using LPS-specific monoc lonal antibodies. The O-side-chain deficiency among the O6-derived mut ants was also examined, and three mutants, A28, R5, and H4, were subse quently chosen for the elucidation of component sugars of the core str ucture of serotype O6 LPS. LPS of strain A28 has L-rhamnose and propor tionally higher amounts of D-glucose, a feature shared by the O5-deriv ed mutant, strain AK1401 (previously demonstrated as a mutant with a c ore-plus-one 0 repeat). In contrast, strains R5 and H4 were shown to b e devoid of L-rhamnose and have low and undetectable amounts of D-gluc ose, respectively, which indicated their core deficiency. The LPS-defi cient or -sufficient characteristics of the P. aepuginosa strains exam ined correlated well with serum sensitivity data. This report represen ts a comprehensive analysis of rough mutants derived from 03 and 05 st rains that have been used by others in many studies and a first look a t the core oligosaccharide region of serotype O6 LPS obtained with the O6-derived mutants generated in this study.