Westfälische Wilhelms-Universität Münster, Institut für Molekulare Mikrobiologie und Biotechnologie, Corrensstr. 3, 48149 Münster, Germany.
Present address: Institute for Technical Microbiology, Mannheim University of Applied Sciences, Mannheim, Germany.
Microbiology (Reading). 2020 Oct;166(10):918-935. doi: 10.1099/mic.0.000961.
Alphaproteobacteria belonging to the group of the sphingomonads are frequently found in biofilms colonizing pure-water systems, where they cause technical and hygienic problems. In this study, physiological properties of sphingomonads for biofilm formation on plastic surfaces were analysed. sp. strain S2M10 was isolated from a used water-filtration membrane and submitted to transposon mutagenesis for isolating mutants with altered biofilm formation. Mutants showing strongly decreased biofilm formation carried transposon insertions in genes for the biosynthesis of the polysaccharide sphingan and for flagellar motility. Flagella-mediated attachment was apparently important for biofilm formation on plastic materials of intermediate hydrophobicity, while a mutant with defect in , encoding the first enzyme in sphingan biosynthesis, showed no biofilm formation on all tested materials. Sphingan-dependent biofilm formation was induced in the presence of specific carbon sources while it was not induced in complex medium with yeast extract and tryptone. The regulation of sphingan-based biofilm formation was investigated by interfering with the CckA/ChpT/CtrA phosphorelay, a central signal-transduction pathway in most Alphaproteobacteria. Construction and ectopic expression of a kinase-deficient histidine kinase CckA caused cell elongation and massive sphingan-dependent cell aggregation. In addition, it caused increased activity of the promotor of . In conclusion, these results indicate that sphingan-based biofilm formation by sphingomonads might be triggered by specific carbon sources under prototrophic conditions resembling a milieu that often prevails in pure-water systems.
鞘脂单胞菌属的α变形菌经常在纯水系生物膜中被发现，在那里它们会引起技术和卫生问题。在这项研究中，分析了生物膜在塑料表面形成过程中鞘脂单胞菌的生理特性。sp. 菌株 S2M10 是从使用过的水过滤膜中分离出来的，并用转座子诱变来分离生物膜形成能力改变的突变体。生物膜形成能力明显降低的突变体携带转座子插入，插入基因分别编码多糖鞘氨醇的生物合成和鞭毛运动。鞭毛介导的附着显然对中亲水性塑料材料上的生物膜形成很重要，而编码鞘氨醇生物合成中第一个酶的基因缺失突变体在所有测试材料上均未形成生物膜。在存在特定碳源的情况下诱导了依赖鞘氨醇的生物膜形成，而在含有酵母提取物和胰蛋白胨的复杂培养基中则未诱导。通过干扰 CckA/ChpT/CtrA 磷酸传递途径，该途径是大多数α变形菌的中央信号转导途径，研究了基于鞘氨醇的生物膜形成的调控。构建并异位表达无激酶活性的组氨酸激酶 CckA 导致细胞伸长和大量依赖鞘氨醇的细胞聚集。此外，它还导致了基因的启动子活性增加。总之，这些结果表明，鞘脂单胞菌依赖鞘氨醇的生物膜形成可能是由特定碳源在类似于纯水系中经常存在的原养条件下触发的。
