Photosynthesis and genome evolution of cyanobacteria from polar environments

极地环境蓝藻的光合作用和基因组进化

• 批准号: 2891929
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2891929
• 关键词: Photosynthesis; genome; evolution; cyanobacteria; polar

Cyanobacteria are the only bacteria capable of oxygenic photosynthesis. They have shaped Earth's biogeochemical cycles and biodiversity for billions of years. Cyanobacteria are cosmopolitan, but they are especially successful in extreme habitats. Particularly, in polar freshwater ecosystems where they form complex cyanobacteria-dominated microbial mat communities and are important primary producers, driving food webs and carbon cycling.However, adaptation of photosynthesis to polar habitats remains poorly understood. In these habitats, low temperatures are often accompanied by extreme fluctuations in irradiance. High light intensities and ultraviolet radiation are common for shallow meltwater ponds on the ice shelves. In contrast, only a tiny fraction of the surface irradiance is transmitted through the ice at the bottom of perennially ice-covered lakes. This suggests that cyanobacteria have a tremendous capacity to acclimate photosynthesis to challenging conditions. The fundamental principles that govern such adaptations can provide insights not only into engineering more robust or resilient strains for biotech applications, translatable toeukaryotic algae and crops, but also on the biological plasticity that enables the endurance of oxygenic photosynthesis over the long history of our constantly changing planet.The aim of the project is to characterize in real time, at a physiological and genomic level, how photosynthesis in cyanobacteria acclimates to harsh environmental conditions using adaptive laboratory evolution experiments.The student will grow Antarctic cyanobacteria in the laboratory to evaluate their fitness and photosynthetic performance under extreme light conditions such as very low or high intensities, different UV radiation levels, and in combination with changes in temperature. Selected populations of Antarctic strains will be gradually acclimated to benign laboratory conditions as to release selective pressures over a period of time. In parallel, laboratorycyanobacteria will be gradually acclimated to harsh polar-like conditions and their fitness compared to Antarctic isolates. Genomes will be sequenced, and genetic changes will be correlated with photosynthetic performance.The NHM also has collections of over 10,000 historic samples of cyanobacteria, including those collected during Captain Scott's British Antarctic Expedition over a century ago that will be sequenced using ancient DNA extraction approaches and compared with cyanobacteria isolates and available metagenome data from Antarctica.

蓝细菌是唯一能够进行光合作用的细菌。数十亿年来，它们塑造了地球的生物化学循环和生物多样性。蓝藻是世界性的，但它们在极端的栖息地特别成功。特别是在极地淡水生态系统中，它们形成复杂的蓝藻主导的微生物垫群落，是重要的初级生产者，推动食物网和碳循环。在这些栖息地，低温往往伴随着辐照度的极端波动。在冰架上的浅水融水池中，强光和紫外线辐射是常见的。相比之下，只有很小一部分的表面辐照度通过常年冰封的湖底的冰传输。这表明，蓝藻有巨大的能力，适应光合作用的挑战性条件。管理这种适应的基本原则不仅可以为生物技术应用提供更强大或更有弹性的菌株，可转化为真核藻类和作物，而且还可以提供生物可塑性，使我们不断变化的星球在漫长的历史中能够承受有氧光合作用。该项目的目的是在真实的时间内，在生理和基因组水平上，蓝细菌的光合作用如何适应恶劣的环境条件下使用适应性实验室进化实验。学生将在实验室中培养南极蓝细菌，以评估它们的适应性和光合性能在极端光照条件下，如非常低或高强度，不同的紫外线辐射水平，并结合温度变化。选定的南极种群将逐渐适应良性的实验室条件，以便在一段时间内释放选择压力。与此同时，实验室蓝藻将逐渐适应严酷的极地条件和他们的健身相比，南极隔离。NHM还收集了超过10，000个蓝藻的历史样本，包括世纪前斯科特船长的英国南极探险队收集的样本，这些样本将使用古代DNA提取方法进行测序，并与蓝藻分离物和南极洲的宏基因组数据进行比较。