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

Position and configuration of double bonds of lipid A-associated monounsaturated fatty acids of Proteobacferia and Rhodobacter capsulatus 37b4

The double bond of dodecenoic acid in the endotoxin-antagonistically acting lipid A of Rhodobacter capsulatus, strains 37b4 and St Louis, was found to have cis-configuration. The position of the double bond was ω7. The mono-unsaturated fatty acids of lipid A from a number of additionally investigated strains of various species of the α-, β-, and γ-subgroups of Proteobacteria (Agrobacterium spp., Azospirillum spp., Rhizobium meliloti, Rhodobacter sphaeroides, Rhodomicrobium vannielii, Rhodopseudomonas blastica, Rhodospirillum salinarum, Sphaerotilus natans, Thiobacillus spp. and Yersinia enterocolitica) have also cis -configuration with the double bond in the ω7-position (one exception), suggesting the anaerobic pathway of biosynthesis to be common for most of them.

Influence of growth temperature on lipid and phosphate contents of surface polysaccharides from the antarctic bacterium Pseudoalteromonas haloplanktis TAC 125

The chemical structural variations induced by different growth temperatures in the lipooligosaccharide and exopolysaccharide components extracted from the Antarctic bacterium Pseudoalteromonas haloplanktis TAC 125 are described. The increase in phosphorylation with the increase in growth temperature seems to be general, because it happens not only for the lipooligosaccharide but also for the exopolysaccharide. Structural variations in the lipid components of lipid A also occur. In addition, free lipid A is found at both 25 and 4 degrees C but not at 15 degrees C, which is the optimal growth temperature, suggesting a incomplete biosynthesis of the lipooligosaccharide component under the first two temperature conditions.

Influence of the glucose concentration on the yield of biomass and lipopolysaccharide in Salmonella cultures

Two Salmonella S-forms and two R-mutants were cultivated in complex medium supplemented with different amounts (0.5-3%) glucose. Cultivation was performed batchwise in a fermentor under aerobic conditions. With all strains investigated, the yield of bacterial mass increased with increasing concentration of glucose. In the case of three strains, the % LPS content of bacteria also increased, thus achieving the aim of this investigation. The synthesis of bacterial mass and LPS did not proceed in parallel and differed from strain to strain. At optimal glucose concentration, the yield of LPS could be increased up to 250%. The chemical composition of the LPS was independent of the glucose concentration. The individual strains exhibited an identical composition with regard to lipid A and polysaccharide when cultured at different glucose concentrations. The uniformity of the molecular distribution of LPS could also be confirmed by SDS-polyacrylamide gel electrophoresis. In the S-form LPSs, also the proportion of the unsubstituted R-form LPS was not affected by the glucose concentration in the culture medium. The present results demonstrate that optimisation of the cultivation conditions with respect to the glucose concentration of the medium would be of advantage especially for Salmonella strains that are cultivated frequently.