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Micro-optics and photosynthetic light-trapping in cyanobacteria

蓝藻的微光学和光合光捕获

基本信息

批准号：
BB/P001807/1
负责人：
Conrad Mullineaux
金额：
$ 43.93万
依托单位：
Queen Mary University of London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FP001807%2F1
关键词：
Micro optics photosynthetic light trapping

项目摘要

Cyanobacteria are bacteria that grow by photosynthesis in a similar manner to plants. They are very diverse in terms of their morphology and extremely abundant in the environment: cyanobacteria in the oceans are the most abundant photosynthetic organisms on the planet and make a huge contribution to the global ecosystem. Synechocystis is a widely-used single-celled model cyanobacterium, with spherical cells about 0.003 mm in diameter. Synechocystis has the ability to move across surfaces by extending and retracting protein fibres called pili. It uses this ability to move towards light sources, and recently we investigated how such a tiny cell could be capable of detecting the position of the light source. We found that the cells act as microscopic spherical lenses, a physical property that enables them to "see" the position of a light source using the same principles that are exploited by the eyes of animals. This surprising observation prompted us to look for related effects in other cyanobacteria with different cell shapes, and we found that a cyanobacterium with elongated rod-shaped cells can trap and channel light within its elongated cell body rather like a microscopic fibre-optic. These effects appear never to have been previously considered. They are important for enabling cyanobacteria to detect the position of light sources, but they may have even more importance for photosynthesis in cyanobacteria. We envisage that photosynthesis could be influenced in several ways. Firstly, lensing effects as observed in Synechocystis could strongly concentrate light in specific regions of the cell, an effect which we think could be beneficial in low light but deleterious in high light. Secondly, fibre-optic light-trapping as observed in rod-shaped cyanobacteria could result in significantly enhanced overall light absorption by the cell. Finally, it is possible that in filamentous cyanobacteria (which consist of long chains of connected cells) the fibre-optic effect could result in light being transmitted from cell to cell, with the potential for light conduction into the interior of crowded biofilms. We think that it is essential to understand the influence of lensing and fibre-optic effects if we are to understand how cyanobacteria are able to maximise the efficiency of photosynthetic growth in the wide variety of environments that they inhabit. In this project we will measure the influence of these optical effects on photosynthesis in three model cyanobacteria: one with spherical cells, one with elongated rod-shaped cells and one with long chains of connected cells. We will quantify the influence of the optical effects on the path of light through the cells, and we will determine whether the effects are simply determined by cell size and shape, or whether they are influenced by specific features of the surface layers of the cells. We will find ways to modify the optical effects, suppressing lensing and fibre-optic trapping either by mutations that affect the cell surface layers or by immersing the cells in media whose refractive index matches that of the cell. This will enable us to quantify the influence of the optical effects on photosynthesis and allow us to determine whether the effects are beneficial or harmful in specific environments. Our results will lead to a better understanding of the growth of cyanobacteria in different environments, and we think that this could lead to a better understanding of the global ecosystem, as well as providing essential information for the efficient exploitation of cyanobacteria as solar-powered cell factories in photobioreactors.

蓝细菌是通过光合作用以类似于植物的方式生长的细菌。它们在形态上非常多样，在环境中极其丰富：海洋中的蓝藻是地球上最丰富的光合生物，对全球生态系统做出了巨大贡献。集胞藻是一种广泛应用的单细胞模式蓝藻，其球形细胞直径约为0.003 mm。集胞藻有能力通过伸展和收缩被称为皮利的蛋白质纤维在表面移动。它利用这种能力向光源移动，最近我们研究了这样一个微小的细胞如何能够检测光源的位置。我们发现，这些细胞就像显微镜下的球形透镜，这种物理特性使它们能够使用与动物眼睛相同的原理“看到”光源的位置。这一令人惊讶的观察促使我们在其他具有不同细胞形状的蓝藻中寻找相关效应，我们发现具有细长杆状细胞的蓝藻可以在其细长的细胞体内捕获和引导光，就像显微镜下的光纤一样。这些影响似乎以前从未被考虑过。它们对于使蓝细菌能够检测光源的位置很重要，但它们对蓝细菌的光合作用可能更重要。我们设想光合作用可以通过几种方式受到影响。首先，在集胞藻中观察到的透镜效应可以在细胞的特定区域强烈地聚集光，我们认为这种效应在弱光下可能是有益的，但在强光下是有害的。其次，在杆状蓝藻中观察到的光纤光捕获可能导致细胞显著增强的整体光吸收。最后，在丝状蓝藻（由连接的细胞组成的长链）中，光纤效应可能导致光在细胞之间传输，并有可能将光传导到拥挤的生物膜内部。我们认为，这是必不可少的，以了解透镜和光纤效应的影响，如果我们要了解蓝藻是如何能够最大限度地提高光合作用的生长效率，在各种各样的环境，他们居住。在这个项目中，我们将测量这些光学效应对光合作用的影响，在三个模型蓝藻：一个球形细胞，一个细长的杆状细胞和一个长链连接的细胞。我们将量化光学效应对光通过细胞的路径的影响，并确定这些效应是否简单地由细胞大小和形状决定，或者它们是否受到细胞表面层的特定特征的影响。我们将找到改变光学效应的方法，通过影响细胞表面层的突变或将细胞浸入折射率与细胞相匹配的介质中来抑制透镜效应和光纤捕获。这将使我们能够量化光学效应对光合作用的影响，并使我们能够确定这些效应在特定环境中是有益还是有害。我们的研究结果将使我们更好地了解不同环境中蓝细菌的生长，我们认为这可以使我们更好地了解全球生态系统，并为有效利用蓝细菌作为太阳能电池工厂提供重要信息。在光生物反应器中。