权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

The molecular microbiology and physics of bacterial flotation

细菌浮选的分子微生物学和物理学

基本信息

批准号：
BB/K001833/1
负责人：
George Salmond
金额：
$ 53.36万
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2013
资助国家：
英国
起止时间：
2013 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FK001833%2F1
关键词：
molecular microbiology physics bacterial flotation

项目摘要

Some aquatic bacteria can make intracellular chambers (made entirely of protein) that are permeable only to environmental gasses. The structures are called gas vesicles (GVs) and they form conglomerates (gas vacuoles) identifiable by phase contrast microscopy. The aquatic bacteria that make GVs may use them for the phenomenon of buoyancy, allowing upward flotation in a static water column. This ability can be useful for some photosynthetic bacteria (e.g. cyanobacteria) that need to rise in a stratified aquatic niche to access light of a specific wavelength, or to acquire nutrients or oxygen at the air-liquid interface, or perhaps to escape predators or competitors. The GVs usually comprise a major protein (GvpA) and a minor protein (GvpC) and form cylindrical structures with apical poles. We recently discovered gas vesicles in strain ATCC39006 of the enterobacterium, Serratia ("related" to E. coli). The existence of GVs in this strain was a unique, and totally unexpected, observation. In addition to production of GV organelles and the capacity to float, this strain has other interesting traits. It makes two antibiotics. One antibiotic is antibacterial (a carbapenem) and another (prodigiosin) can kill protozoans and other microbes. ATCC39006 can swim via flagella (motility) and can swarm on solid surfaces and make surface detergent molecules (biosurfactants) enabling spreading and colonisation of new niches or host surfaces. The strain also rots plants (potato) by secreting plant cell wall degrading enzymes and it kills microscopic worms (Caenorhabditis elegans) and so it is also nematicidal. We identified the cluster of 19 GV genes in strain ATCC39006 and we engineered E. coli strains that expressed the Serratia GV genes and allowed E. coli to float up to the air-liquid interface in static culture. Production of the GVs in Serratia was bacterial cell density-dependent in a process called "Quorum Sensing" controlled by a diffusible chemical signal that moves between cells. The signalling molecule is essential for production of the GVs in Serratia; quorum-sensing mutants don't float. Therefore, in this bacterium, an intercellular chemical signal controls the development of intracellular organelles and thus the chemical communication signal is also a morphogen. Quorum sensing also controls the production of the antibiotics in this strain and so these toxic molecules are made at the same time as the GVs are assembled. We showed that GV production was also up-regulated by oxygen limitation, implying that GVs may allow flotation to the liquid surface to acquire oxygen. In collaboration with Professor Raymond Goldstein in the Department of Applied Mathematics and Theoretical Physics (DAMTP) in Cambridge, we have been investigating the phenomenon of buoyancy in this bacterium. Based on our knowledge of the genetics, physiology and physics of mobility in this bacterium we have developed a testable working hypothesis as to why GV production, and flotation, is under quorum sensing control; responsive to oxygen levels, and developmentally preferred to flagellar motility. Our model also predicts why the production of the two antibiotics has evolved to be co-incident with the development of the GVs, and flotation. We will now investigate the fascinating connections between bacterial cell population density, motility, bioconvection, GV development, buoyancy and antibiotic production. This study has wide ramifications. It impinges on areas such as ecological adaptation to environmental stress cues in microbes; intercellular chemical communication in bacteria; bacterial organelle morphogenesis; and the fitness value of microbial conflict and niche defence. Our understanding of the evolution of some of these biological processes will be significantly enhanced by an appreciation of the underlying mathematical physics that describes their behaviour; an exciting interdisciplinary study where microbiology meets mathematics!

一些水生细菌可以制造只对环境气体渗透的胞内小室(完全由蛋白质组成)。这些结构被称为气泡(GV)，它们形成的集合体(气泡)可通过相差显微镜识别。制造GV的水生细菌可能会利用它们来产生浮力现象，允许在静止的水柱中向上漂浮。这种能力对于一些需要在分层的水生生态位中上升以获取特定波长的光，或在气液界面获取营养或氧气，或者可能是为了躲避捕食者或竞争对手的光合作用细菌(如蓝藻)来说是有用的。GV通常由一个主要蛋白(GvpA)和一个次要蛋白(GvpC)组成，并形成圆柱形结构，顶端极。我们最近在肠杆菌菌株ATCC39006中发现了气泡，沙雷氏菌(与大肠杆菌有关)。这种毒株中GV的存在是一种独特的、完全出乎意料的观察。除了产生GV细胞器和漂浮能力外，该菌株还有其他有趣的特征。它制造两种抗生素。一种抗生素是抗菌的(一种碳青霉烯类)，另一种(灵芝菌素)可以杀死原生动物和其他微生物。ATCC39006可以通过鞭毛(运动性)游泳，可以聚集在固体表面，并制造表面洗涤剂分子(生物表面活性剂)，使新的利基或宿主表面能够传播和定居。该菌株还通过分泌植物细胞壁降解酶来腐烂植物(马铃薯)，并杀死微小的蠕虫(秀丽线虫)，因此它也是杀线虫。我们在ATCC39006菌株中鉴定了19个GV基因簇，并通过工程技术获得了表达沙雷氏菌GV基因的菌株，并允许大肠杆菌在静态培养中漂浮到气液界面。沙雷氏菌中GVS的产生依赖于细菌细胞密度，这一过程被称为“群体感应”，由细胞间移动的可扩散化学信号控制。信号分子对于沙雷氏菌中GV的产生是必不可少的；群体感应突变体不会漂浮。因此，在这种细菌中，细胞间的化学信号控制着细胞内细胞器的发育，因此化学通信信号也是一种形态发生。群体感应还控制着该菌株中抗生素的生产，因此这些有毒分子是在GV组装的同时制造的。我们发现，GV的产生也受到氧气限制的上调，这意味着GVS可能允许漂浮到液体表面以获取氧气。在剑桥大学应用数学和理论物理系的雷蒙德·戈尔茨坦教授的合作下，我们一直在研究这种细菌中的浮力现象。基于我们对这种细菌移动性的遗传学、生理学和物理学的知识，我们已经开发了一个可测试的工作假说，即为什么GV的产生和漂浮受到群体感应的控制；对氧气水平的反应，以及发育上对鞭毛运动的偏好。我们的模型还预测了为什么这两种抗生素的生产演变为与GVS和浮选的发展同时发生。我们现在将研究细菌细胞密度、运动性、生物对流、GV发育、浮力和抗生素生产之间的有趣联系。这项研究具有广泛的影响。它影响的领域包括：微生物对环境应激信号的生态适应；细菌中的细胞间化学通讯；细菌细胞器的形态发生；微生物冲突和生态位防御的适宜性价值。通过对描述它们行为的基本数学物理的欣赏，我们对其中一些生物过程的进化的理解将大大增强；这是一项令人兴奋的跨学科研究，其中微生物学与数学相遇！

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

CRISPR-Cas gene-editing reveals RsmA and RsmC act through FlhDC to repress the SdhE flavinylation factor and control motility and prodigiosin production in Serratia.

DOI：
10.1099/mic.0.000283
发表时间：
2016-06
期刊：
Microbiology (Reading, England)
影响因子：
0
作者：
Hampton HG;McNeil MB;Paterson TJ;Ney B;Williamson NR;Easingwood RA;Bostina M;Salmond GPC;Fineran PC
通讯作者：
Fineran PC

Draft Genome Sequence of Serratia sp. Strain ATCC 39006, a Model Bacterium for Analysis of the Biosynthesis and Regulation of Prodigiosin, a Carbapenem, and Gas Vesicles.

DOI：
10.1128/genomea.01039-13
发表时间：
2013-12-12
期刊：
Genome announcements
影响因子：
0
作者：
Fineran PC;Iglesias Cans MC;Ramsay JP;Wilf NM;Cossyleon D;McNeil MB;Williamson NR;Monson RE;Becher SA;Stanton JA;Brügger K;Brown SD;Salmond GP
通讯作者：
Salmond GP

Structure of the Fundamental Lipopeptide Surfactin at the Air/Water Interface Investigated by Sum Frequency Generation Spectroscopy

通过和频发生光谱研究空气/水界面上基本脂肽表面活性剂的结构