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首页> 外文期刊>Journal of bacteriology >Induction of Rapid Detachment in Shewanella oneidensis MR-1 Biofilms
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Induction of Rapid Detachment in Shewanella oneidensis MR-1 Biofilms

机译：快速分离希瓦氏菌MR-1生物膜的诱导。

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Active detachment of cells from microbial biofilms is a critical yet poorly understood step in biofilm development. We discovered that detachment of cells from biofilms of Shewanella oneidensis MR-1 can be induced by arresting the medium flow in a hydrodynamic biofilm system. Induction of detachment was rapid, and substantial biofilm dispersal started as soon as 5 min after the stop of flow. We developed a confocal laser scanning microscopy-based assay to quantify detachment. The extent of biomass loss was found to be dependent on the time interval of flow stop and on the thickness of the biofilm. Up to 80% of the biomass of 16-h-old biofilms could be induced to detach. High-resolution microscopy studies revealed that detachment was associated with an overall loosening of the biofilm structure and a release of individual cells or small cell clusters. Swimming motility was not required for detachment. Although the loosening of cells from the biofilm structure was observed evenly throughout thin biofilms, the most pronounced detachment in thicker biofilms occurred in regions exposed to the flow of medium, suggesting a metabolic control of detachability. Deconvolution of the factors associated with the stop of medium flow revealed that a sudden decrease in oxygen tension is the predominant trigger for initiating detachment of individual cells. In contrast, carbon limitation did not trigger any substantial detachment, suggesting a physiological link between oxygen sensing or metabolism and detachment. In-frame deletions were introduced into genes encoding the known and putative global transcriptional regulators ArcA, CRP, and EtrA (FNR), which respond to changes in oxygen tension in S. oneidensis MR-1. Biofilms of null mutants in arcA and crp were severely impacted in the stop-of-flow-induced detachment response, suggesting a role for these genes in regulation of detachment. In contrast, an ΔetrA mutant displayed a variable detachment phenotype. From this genetic evidence we conclude that detachment is a biologically controlled process and that a rapid change in oxygen concentration is a critical factor in detachment and, consequently, in dispersal of S. oneidensis cells from biofilms. Similar mechanisms might also operate in other bacteria.
机译：从微生物生物膜上主动分离细胞是生物膜开发中的关键但了解甚少的步骤。我们发现，通过阻止流体动力生物膜系统中的介质流，可以诱导细胞从One.Shewanella oneidensis MR-1生物膜中脱离。分离的诱导迅速，并且在停止流动后5分钟就开始大量的生物膜扩散。我们开发了一种基于共聚焦激光扫描显微镜的测定法，以量化脱离。发现生物质损失的程度取决于流动停止的时间间隔和生物膜的厚度。可以诱导16小时生物膜中80％的生物量脱落。高分辨率显微镜研究表明，分离与生物膜结构的整体松弛以及单个细胞或小细胞簇的释放有关。分离不需要游泳运动。尽管在整个薄生物膜中均匀观察到细胞从生物膜结构上松动，但较厚的生物膜中最明显的分离发生在暴露于介质流的区域，这表明代谢控制了分离性。对与介质流动停止有关的因素进行反卷积表明，氧张力的突然下降是引发单个细胞脱离的主要诱因。相反，碳限制并没有引发任何实质性的脱离，表明氧感测或代谢与脱离之间存在生理联系。框内缺失被引入编码已知和假定的全局转录调节因子ArcA，CRP和EtrA（FNR）的基因中，这些基因对 S中的氧张力变化做出响应。 oneidensis MR-1。 arcA 和 crp 中的无效突变体的生物膜在水流诱导的脱离反应中受到严重影响，表明这些基因在脱离调节中的作用。相反，Δ etrA 突变体表现出可变的分离表型。从这些遗传证据中我们得出结论，脱离是一个生物控制的过程，氧浓度的快速变化是脱离的关键因素，因此也是 S扩散的关键因素。生物膜中的oneidensis 细胞。类似的机制也可能在其他细菌中起作用。

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