Effects of culture method and growth phase on free lipid composition of Yersinia pseudotuberculosis.

The influence of culture method (free-floating cells in liquid nutrient broth or bacteria attached to agar surface on solid agarized medium of the same formulation) and bacterial age on the composition of free lipids in Yersinia pseudotuberculosis (O:Ib serovar, strain KS 3058) grown in the cold (5 degrees C) has been investigated. The specific growth rate of the bacteria on solid medium was about threefold less than that in liquid medium. The qualitative composition of phospholipids and fatty acids only slightly depended on the bacterial culture method. At the same time, the colonially growing cultures contained somewhat more total lipids, they synthesized more phospholipids, in the linear growth phase they contained more lysophosphatides, and they had higher fatty acid unsaturation index and higher pathogenic potential than their "planktonic" counterparts grown in otherwise identical conditions. The bacterial growth phase influenced the amount of 3-hydroxytetradecanoic acid and, indirectly, that of lipopolysaccharide. The dynamics of changes in the amount of this acid with bacterial age was opposite in the surface and broth cultures.