Abstract—

At an elevated copper content, the viability of Azospirillum baldaniorum on wheat seedling roots and the number of cells colonizing the roots and forming biofilms depended on the physicochemical properties of the lipopolysaccharides ( LPSs) synthesized by these bacteria. Compared to the strain Cal⁺ LpsI LpsII A. baldaniorum strain Sp245, its mutants Cal^– LpsI^– KM252, Lps II^– KM139, and Cal^– LpsII^– Mot^– KM018 colonized the roots less efficiently and formed thinner biofilms. Changes in the polysaccharide synthesis in KM252, KM139, and KM018 mediated increased copper accumulation by the cells and decreased the resistance of bacterial cultures to the negative effect of copper ions. Copper excess in planta and/or on the model polystyrene surface resulted in higher levels of the polysaccharide antigens in the biofilms of strain Sp245 and of its mutants with altered glycopolymer composition. Inoculation with strain Sp245 had a positive effect on the growth of wheat stems and leaves both at copper concentrations which had no noticeable effect on the growth of any of the partners (0.001 mM) and at elevated concentrations of copper ions (up to 0.5 mM). Strains КМ018, КМ139, and КМ252 had a positive effect on the seedlings only at high copper concentrations in the medium.

中文翻译：

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脂多糖合成的变化影响铜含量升高时植物中固氮螺菌生物膜的形成

摘要——

在铜含量升高的情况下，Azospirillum baldaniorum在小麦幼苗根部的生存能力以及在根部定植和形成生物膜的细胞数量取决于这些细菌合成的脂多糖 (LPS) 的理化特性。与 Cal ⁺ LpsI LpsII A. baldaniorum菌株 Sp245 相比，其突变体 Cal ^– LpsI ^– KM252、Lps II ^– KM139 和 Cal ^– LpsII ^– Mot ^–KM018 不太有效地定植根部并形成较薄的生物膜。KM252、KM139 和 KM018 中多糖合成的变化介导了细胞铜积累的增加，并降低了细菌培养物对铜离子负面影响的抵抗力。植物中铜过量和/或在模型聚苯乙烯表面上导致菌株 Sp245 及其具有改变的糖聚合物组成的突变体的生物膜中的多糖抗原水平更高。在铜浓度（0.001 mM）和铜离子浓度升高（高达 0.5 mM）下，接种菌株 Sp245 对小麦茎和叶的生长都有积极影响，对任何伙伴的生长都没有明显影响. 菌株 КМ018、КМ139 和 КМ252 仅在培养基中的高铜浓度下对幼苗产生积极影响。