Characteristics of Pseudomonas aurantiaca DNA supramolecular complexes at various developmental stages

Differences in viscoelasticity (η) and molecular mass (M) values, as well as in the fatty acid profile of lipids in DNA supramolecular complexes (SC), isolated from Pseudomonas aurantiaca cultures at the exponential and stationary growth phases, were established for the first time. Typical characteristics of DNA SC from actively growing cells were the following: η = 315 ± 15 dl/g, MDNA = 39 x 10⁶ Da, C₁₆:₀ > C₁₈:₀ > C₁₈:₁ present as basic fatty acids (FA) in a pool of loosely DNA-bound lipids; the tightly DNA-bound lipid fraction consisted of only two acids C₁₈:₀ > C₁₆:₀. Significantly higher values of viscoelasticity η = 779 ± 8 dl/g and MDNA = 198 x 10⁶ Da were observed for DNA SC of the stationary phase cells; one more FA, C₁₄:₀, was detected in the loosely bound lipid fraction, while lipids tightly bound to DNA contained mainly C₁₆:₀ > C₁₈:₁ > C₁₈:₀ > C₁₄:₀ FA. The content of saturated FA in the DNA-bound lipids in the stationary phase cells was twice as high than in the exponential phase cells. The fraction of tightly bound lipids from the stationary phase cells contained nine times more unsaturated fatty acids than the fraction from proliferating cells. These differences in FA composition of DNA-bound lipids demonstrate the importance of lipids for the structural organization and functioning of genomic DNA during bacterial culture development.