Role of Caulobacter Cell Surface Structures in Colonization of the Air-Liquid Interface
Role of Caulobacter Cell Surface Structures in Colonization of the Air-Liquid Interface
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DOI：
10.1128/jb.00064-19
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发表时间：
2019-09-01
影响因子：
3.2
通讯作者：
Fiebig, Aretha
中科院分区：
文献类型：
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作者：
Fiebig, Aretha
在水环境中，硫杆菌属(Caulbacter spp.)可以在被称为纽斯顿的液体和空气的交界处找到。我报道了一种方法来研究新月形杆菌在气液界面的定植和膜生物膜发育的时间特征，并确定了细胞表面结构在这一过程中的作用。在这个界面上，新月藻最初形成一层单层细胞，带有一种被称为Holdfast的表面粘附素。当从液体表面剥离时，这种单分子膜强烈地附着在玻璃上。单层随后发展成一种三维结构，高度富含被称为玫瑰花环的柄细胞簇。随着这种薄膜的成熟，它对玻璃表面的粘附性变得更强，粘附性更弱。缺乏鞭毛的突变菌株不能有效地到达表面，而缺乏IV型菌毛的菌株在三维膜层的组织上表现出缺陷。不能合成Holdfast的菌株不能在空气和液体的交界处聚集，也不会形成薄膜。相衬图像支持一种模型，在该模型中，Holdfast的功能是在气液边界捕获新月形藻细胞。与Holdfast不同，Crescentus不需要鞭毛也不需要IV型菌毛来分割到气液界面。虽然众所周知，Holdfast能够附着在固体表面，但这项研究提供了证据，证明Holdfast具有物理化学性质，允许将不活动的母细胞分配到气液界面，并促进这种微环境的定居。在水生环境中，空气界面的边界通常高度富含营养物质和氧气。在许多情况下，定居这一利基可能会带来显著的健康优势。这项研究提供的证据表明，细胞表面的粘附素，即所谓的Holdfast，能够使新月杆菌分裂并定植于气-液界面。其他表面结构，包括鞭毛和IV型菌毛，是在这一边界上定植和生物膜形成的重要决定因素。考虑到类Holdfast粘附素在弧菌属中广泛保守。和不同类别的甲变态细菌的其他成员一样，这些表面结构可以广泛地发挥作用，促进在一系列生态环境中的气液边界的定植，包括淡水、海洋和土壤生态系统。
In aquatic environments, Caulobacter spp. can be found at the boundary between liquid and air known as the neuston. I report an approach to study temporal features of Caulobacter crescentus colonization and pellicle biofilm development at the air-liquid interface and have defined the role of cell surface structures in this process. At this interface, C. crescentus initially forms a monolayer of cells bearing a surface adhesin known as the holdfast. When excised from the liquid surface, this monolayer strongly adheres to glass. The monolayer subsequently develops into a three-dimensional structure that is highly enriched in clusters of stalked cells known as rosettes. As this pellicle film matures, it becomes more cohesive and less adherent to a glass surface. A mutant strain lacking a flagellum does not efficiently reach the surface, and strains lacking type IV pili exhibit defects in organization of the three-dimensional pellicle. Strains unable to synthesize the holdfast fail to accumulate at the boundary between air and liquid and do not form a pellicle. Phase-contrast images support a model whereby the holdfast functions to trap C. crescentus cells at the air-liquid boundary. Unlike the holdfast, neither the flagellum nor type IV pili are required for C. crescentus to partition to the air-liquid interface. While it is well established that the holdfast enables adherence to solid surfaces, this study provides evidence that the holdfast has physicochemical properties that allow partitioning of nonmotile mother cells to the air-liquid interface and facilitate colonization of this microenvironment.IMPORTANCE In aquatic environments, the boundary at the air interface is often highly enriched with nutrients and oxygen. Colonization of this niche likely confers a significant fitness advantage in many cases. This study provides evidence that the cell surface adhesin known as a holdfast enables Caulobacter crescentus to partition to and colonize the air-liquid interface. Additional surface structures, including the flagellum and type IV pili, are important determinants of colonization and biofilm formation at this boundary. Considering that holdfast-like adhesins are broadly conserved in Caulobacter spp. and other members of the diverse class Alphaproteobacteria, these surface structures may function broadly to facilitate colonization of air-liquid boundaries in a range of ecological contexts, including freshwater, marine, and soil ecosystems.