Calcium Increases Xylella fastidiosa Surface Attachment, Biofilm Formation, and Twitching Motility
Calcium Increases Xylella fastidiosa Surface Attachment, Biofilm Formation, and Twitching Motility
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DOI：
10.1128/aem.06501-11
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发表时间：
2012-03-01
影响因子：
4.4
通讯作者：
De La Fuente, Leonardo
中科院分区：
文献类型：
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作者：
Cruz, Luisa F.;Cobine, Paul A.;De La Fuente, Leonardo
苛养木杆菌 (Xylella fastidiosa) 是一种植物病原细菌，可在木质部导管内形成生物膜，这一过程被认为受到木质部汁液化学成分的影响。在这项工作中，在体外条件下分析了钙对 X. fastidiosa 生物膜的产生和运动的影响。在使用八种金属对 96 孔板进行剂量反应研究后，当培养基中添加至少 1.0 mM CaCl2 时，观察到生物膜形成的最强增加。通过细胞外 (EGTA, 1.5 mM) 和细胞内 [1,2-双(邻氨基苯氧基)乙烷-N,N,N',N'-四乙酸乙酰氧基甲酯 (BAPTA/AM), 75 muM] 螯合剂去除 Ca 减少了生物膜形成，但不影响浮游生长。如微流体室测定和其他测定所示，Ca 浓度影响对基底的粘附力、生物膜厚度、细胞间聚集和抽搐运动。当细胞用四环素处理时，Ca 对粘附的作用消失，这表明 Ca 在细胞粘附中具有代谢或调节作用。当将 Ca 添加到培养基中时，缺乏 I 型和 IV 型菌毛的双突变体 (fimA pilO) 不会改善生物膜的形成或附着，而 I 型 (fimA) 或 IV 型 (pilB) 菌毛的单突变体在较高 Ca 浓度的条件下形成更多的生物膜。培养基中 Ca 的浓度对胞外多糖产生的水平没有显着影响。我们的研究结果表明，Ca 在生物膜形成中的作用可能与生物膜建立的初始表面和细胞间附着和定植阶段有关，这些阶段依赖于菌毛结构的关键功能。
Xylella fastidiosa is a plant-pathogenic bacterium that forms biofilms inside xylem vessels, a process thought to be influenced by the chemical composition of xylem sap. In this work, the effect of calcium on the production of X. fastidiosa biofilm and movement was analyzed under in vitro conditions. After a dose-response study with 96-well plates using eight metals, the strongest increase of biofilm formation was observed when medium was supplemented with at least 1.0 mM CaCl2. The removal of Ca by extracellular (EGTA, 1.5 mM) and intracellular [1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA/AM), 75 mu M] chelators reduced biofilm formation without compromising planktonic growth. The concentration of Ca influenced the force of adhesion to the substrate, biofilm thickness, cell-to-cell aggregation, and twitching motility, as shown by assays with microfluidic chambers and other assays. The effect of Ca on attachment was lost when cells were treated with tetracycline, suggesting that Ca has a metabolic or regulatory role in cell adhesion. A double mutant (fimA pilO) lacking type I and type IV pili did not improve biofilm formation or attachment when Ca was added to the medium, while single mutants of type I (fimA) or type IV (pilB) pill formed more biofilm under conditions of higher Ca concentrations. The concentration of Ca in the medium did not significantly influence the levels of exopolysaccharide produced. Our findings indicate that the role of Ca in biofilm formation may be related to the initial surface and cell-to-cell attachment and colonization stages of biofilm establishment, which rely on critical functions by fimbrial structures.