[Effect of cultivation parameters on the composition of extracellular polysaccharide containing substances in...

Maintenance of pH 7.0 during the fermentation period favors accumulation of high-molecular polysaccharide-containing components, the so-called lipopolysaccharide-protein and polysaccharide-lipid complexes, in the capsules and culture medium. Increased pH of the culture medium to 8.0 reduced the period of exponential growth and the yield of polysaccharide-containing complexes as compared to the optimal conditions. Maintenance of pH 5.5 suppressed the culture growth and polysaccharide production. The polysaccharide-lipid complexes obtained when pH was stabilized at the level of 7.0-8.0 had a relatively low molecular weight and contained only acidic polysaccharides. The use of potassium gluconate instead of sodium malate as a source of carbon in the culture medium changed the polysaccharide composition and increased the content of glucosamine, which increased the attraction of polysaccharides to wheat germ agglutinin. Prolongation of Azospirillum cultivation to five days introduced new glucose-containing polysaccharide components in the capsule.