The phytopathogenic gram-positive bacterium Clavibacter sepedonicus (Cms) causes potato ring rot disease, which causes significant economic losses. Currently, there are no effective agents for regulating the abundance of this bacterium. Previously, the authors of this article showed that selenium and arabinogalactan nanocomposites (Se/AG NCs) can cause changes in the morphology of the Cms cells, leading to their destruction. As a probable mechanism of antibacterial action of NC, it has been suggested that NCs affect the composition of fatty acids (FAs) in the membrane lipids of the studied phytopathogen. The aim of this work was to study the effect of Se/AG NCs (with Se content of 3.4% and 6.4%) and their precursors on the qualitative FA composition of the Cms membrane lipids using chromatography-mass spectrometry. A unique FA profile of Cms is revealed, which is represented by 17 FA containing from 12 to 20 carbon atoms. Low levels of unsaturated FAs and high levels of branched-chain FAs (iso- and anteiso-fatty acids) were noted. The content of iso-FAs in Cms significantly increased after the treatment of the bacteria with Se/AG NCs and their precursors. Indirect assessment of the activity of acyl-lipid ω9-, ω6-, and ω3-desaturases showed an increase in their activity under the action of NCs. Exposure to Se/AG NCs increased the degree of unsaturation of fatty acids and increased the fluidity of the Cms membranes; the higher the selenium content in NCs, the higher the sum of unsaturated and branched fatty acids. We suggest that the change in the FA composition induced by Se/AG NCs may be one of the possible mechanisms of the antibacterial action of these nanocomposites.
Graskova et al. (Thu,) studied this question.