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首页> 外文期刊>Applied Microbiology >Pseudomonas syringae Increases Water Availability in Leaf Microenvironments via Production of Hygroscopic Syringafactin
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Pseudomonas syringae Increases Water Availability in Leaf Microenvironments via Production of Hygroscopic Syringafactin

机译：丁香假单胞菌通过产生吸湿性丁香脂素增加叶片微环境中的水分利用

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The epiphytic bacterium Pseudomonas syringae strain B728a produces the biosurfactant syringafactin, which is hygroscopic. The water-absorbing potential of syringafactin is high. Syringafactin attracts 250% of its weight in water at high relative humidities but is less hygroscopic at lower relative humidities. This finding suggests that the benefit of syringafactin to the producing cells is strongly context dependent. The contribution of syringafactin to the water availability around cells on different matrices was assessed by examining the water stress exhibited by biosensor strains expressing gfp via the water-stress-activated proU promoter. Wild-type cells exhibited significantly less green fluorescent protein (GFP) fluorescence than a syringafactin-deficient strain on dry filters in atmospheres of high water saturation, as well as on leaf surfaces, indicating greater water availability. When infiltrated into the leaf apoplast, wild-type cells also subsequently exhibited less GFP fluorescence than the syringafactin-deficient strain. These results suggest that the apoplast is a dry but humid environment and that, just as on dry but humid leaf surfaces, syringafactin increases liquid water availability and reduces the water stress experienced by P. syringae.IMPORTANCE Many microorganisms, including the plant pathogen Pseudomonas syringae, produce amphiphilic compounds known as biosurfactants. While biosurfactants are known to disperse hydrophobic compounds and to reduce water tension, they have other properties that can benefit the cells that produce them. Leaf-colonizing bacteria experience frequent water stress, since liquid water is present only transiently on or in leaf sites that they colonize. The demonstration that syringafactin, a biosurfactant produced by P. syringae, is sufficiently hygroscopic to increase water availability to cells, thus relieving water stress, reveals that P. syringae can modify its local habitat both on leaf surfaces and in the leaf apoplast. Such habitat modification may be a common role for biosurfactants produced by other bacterial species that colonize habitats (such as soil) that are not always water saturated.
机译：附生细菌丁香假单胞菌菌株B728a产生具有吸湿性的生物表面活性剂丁香脂素。丁香脂素的吸水潜力高。丁香皂苷在较高的相对湿度下在水中吸引其重量的250％，但在较低的相对湿度下吸湿性较小。该发现表明丁香脂素对产生细胞的益处强烈取决于背景。通过检查由水压力激活的proU启动子表达gfp的生物传感器菌株表现出的水分胁迫，来评估丁香皂甙对不同基质细胞周围水可用性的贡献。在高水饱和度的大气中以及在叶子表面上，野生型细胞在干燥过滤器上表现出的绿色荧光蛋白（GFP）荧光明显少于丁香素缺乏型菌株，这表明水的利用率更高。当浸润到叶质外体中时，野生型细胞随后也显示出比丁香脂素缺陷型菌株少的GFP荧光。这些结果表明，质外体处于干燥但潮湿的环境中，就像在干燥但潮湿的叶片表面上一样，丁香脂素增加了液态丁香假单胞菌的液态水利用率并减少了水分胁迫。重要的微生物包括植物病原体丁香假单胞菌生产两亲性化合物，称为生物表面活性剂。虽然已知生物表面活性剂可分散疏水性化合物并降低水张力，但它们还有其他特性可以使产生它们的细胞受益。叶片定殖细菌经常遭受水分胁迫，因为液态水仅在它们定殖的叶片上或叶片中短暂存在。丁香假单胞菌产生的生物表面活性剂丁香脂素具有足够的吸湿性，可以增加细胞对水的利用率，从而减轻水分胁迫，这一事实表明，丁香假单胞菌可以改变其在叶表面和叶质外体中的栖息地。对于其他细菌物种产生的生物表面活性剂来说，这种栖息地的修饰可能是常见的作用，这些细菌在不总是被水饱和的栖息地（例如土壤）中定殖。

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