Cell envelope components contributing to biofilm growth and survival of Pseudomonas putida in low‐water‐content habitats
Cell envelope components contributing to biofilm growth and survival of Pseudomonas putida in low‐water‐content habitats
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DOI：
10.1111/j.1365-2958.2004.04008.x
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发表时间：
2004-05
影响因子：
3.6
通讯作者：
M. van de Mortel;L. Halverson
中科院分区：
文献类型：
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作者：
M. van de Mortel;L. Halverson
陆地生境中的细菌经常作为生物膜群落居住在不饱和表面上，即生物膜被覆盖在厚度取决于环境条件的水膜中。这些生境中的水的可利用性受到水的渗透压（溶质胁迫）和基质胁迫所造成的细胞脱水的影响，基质胁迫随着含水量的减少而增加。不幸的是，我们对低含水量栖息地中细菌生长所需的分子机制了解相对较少。在这里，我们描述了使用mini-Tn 5-′phoA来鉴定恶臭假单胞菌中受基质水分胁迫控制的基因，并产生脱水耐受性缺陷的突变体。我们确定了20个基因，诱导的基质应力，但不是由一个等效的溶质应力，11个基因诱导的基质和溶质应力，3个基因诱导的溶质应力和3个基因被抑制的基质应力。在实验室培养基中分析了它们的表达模式，并评估了它们对脱水耐受性的贡献。26个基因与完整的恶臭假单胞菌KT 2440基因组序列或质粒pWWO序列中存在的序列同源，这些基因参与蛋白质命运、营养或溶质获取、能量产生、运动性、藻酸盐生物合成或细胞包膜结构，并且5个基因的功能无法从序列中预测。总之，这些基因及其对干燥耐受性的重要性提供了低含水量栖息地中细菌所感知的环境的观点，并表明在低含水量栖息地中生长的适应机制与在高渗透压栖息地中生长的适应机制不同。
Bacteria in terrestrial habitats frequently reside as biofilm communities on surfaces that are unsaturated, i.e. biofilms are covered in water films varying in thickness depending on the environmental conditions. Water availability in these habitats is influenced by the osmolarity of the water (solute stress) and by cellular dehydration imposed by matric stress, which increases as water content decreases. Unfortunately, we understand relatively little about the molecular mechanisms required for bacterial growth in low‐water‐content habitats. Here, we describe the use of mini‐Tn5‐′phoA to identify genes in Pseudomonas putida that are matric water stress controlled and to generate mutants defective in desiccation tolerance. We identified 20 genes that were induced by a matric stress but not by a thermodynamically equivalent solute stress, 11 genes were induced by both a matric and a solute stress, three genes were induced by a solute stress and three genes were repressed by a matric stress. Their patterns of expression were analysed in laboratory media, and their contribution to desiccation tolerance was evaluated. Twenty‐six genes were homologous to sequences present in the completed P. putida KT2440 genome sequence or plasmid pWWO sequence that are involved in protein fate, nutrient or solute acquisition, energy generation, motility, alginate biosynthesis or cell envelope structure, and the function of five could not be predicted from the sequence. Together, these genes and their importance to desiccation tolerance provide a view of the environment perceived by bacteria in low‐water‐content habitats, and suggest that the mechanisms for adaptation for growth in low‐water‐content habitats are different from those for growth in high‐osmolarity habitats.