title: The influence of low growth temperature on the amount of free R lipopolysaccharide, on the expression of R-core determinants and on O-chain lengths in Salmonella S forms.
abstract: Ten Salmonella strains belonging to five serological groups were cultivated both at 37 degrees C and close to their individual temperature minima at 12-14 degrees C and the composition of their cell wall lipopolysaccharides (LPS) was compared. When grown at low temperature, the proportion of unsubstituted (free) R-LPS in the total LPS moiety increased significantly in 6 strains, whereas in the other strains, no change or even a slight decrease in the R-LPS proportion was observed as judged from the analyses by SDS-PAGE. In the immunoblot, the R-LPSs from 9 out of 10 strains showed a modified reactivity against a set of specific Salmonella R antisera (anti-Ra, anti-Rb1, anti-Rb2, anti-Rc). In most cases, the decrease in Rb1 reactivity was paralleled by an increase in Rb2 reactivity and also by an increase in the total amount of free R-LPS. The electrophoretic mobility of free R-LPS was changed in 7 out of 10 strains, although the changes were not unidirectional. All changes occurred only in the range of the Ra-Rb1 chemotypes and no significant correlation to the serological grouping of the strains was evident. When grown at low temperature, the average number of O-repeating units was reduced in the majority of cases and in some cases, also the banding profile in SDS-PAGE in the S-LPS region was modified. The fatty acid spectra showed some changes which were in accordance with previous results, namely a decrease in the content of C-12:0 and C-16:0 and an increase in that of C-14:0 and C-16:1. The different influences of the growth temperature on the LPS biosynthesis of different Salmonella strains may be a result of the genetic diversity of this group of microorganisms.
authors.affiliation: Max-Planck-Institut für Immunbiologie, Freiburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schlecht
authors.forename: H
authors.initials: H
authors.lastname: Mayer
mesh_terms: D004591:Electrophoresis, Polyacrylamide Gel; D005227:Fatty Acids / Q000032:analysis; D007106:Immune Sera / Q000276:immunology; D008070:Lipopolysaccharides / Q000032:analysis* / Q000737:chemistry / Q000276:immunology; D012475:Salmonella / Q000737:chemistry* / Q000254:growth & development; D013696:Temperature
chemical_list: D005227:Fatty Acids; D007106:Immune Sera; D008070:Lipopolysaccharides