Investigating widespread regulation of nitrogen assimilation at the level of RNA in bacteria

氮是生物系统中的关键元素之一，因为生命的组成部分需要大量的氮。人类赖以生存和生长的氮源相当有限，我们从食物中复杂的有机化合物中获取所需的氮。相比之下，微生物的新陈代谢更具适应性，细菌可以从自然界中存在的一系列更简单的形式(如硝酸盐)中获取所需的氮。最近，由于工业固定了大气中存在的相对惰性的氮气，环境中人造氮气的数量急剧增加。随着世界人口的增长，为了满足这一需求，人们采用了更密集的农业措施来提高作物产量，包括在现代农业实践中广泛使用合成硝酸盐化肥。硝酸盐在水中高度溶解，很容易在径流中流失，在河流、湖泊和海洋中积累，为能够利用硝酸盐生长的细菌提供丰富的营养。在农业领域，土壤微生物使用硝酸盐而不是预期的作物，不仅在经济上是浪费的，而且可能会产生一些意想不到的后果。据预测，其中一个后果是环境中特定细菌对溶解有机碳的消耗增加。这对许多土壤类型的肥力和完整性构成了重大风险，因为利用硝酸盐的细菌种群分解分解了土壤中的有机成分。土壤有机质的显著减少不仅会对具有商业价值的农业用地的长期可持续性产生负面影响，而且增加微生物对这些二氧化碳汇的作用也可能有助于全球气候变化。在这个研究计划中，我们将讨论我们已经确定的一个关键基因的作用，该基因对模式硝酸盐利用土壤细菌反硝化副球藻的利用至关重要，该细菌在世界各地的实验室中得到了广泛的研究。据预测，该基因将产生一种调节蛋白，该蛋白可能控制细菌如何利用硝酸盐和碳进行生长。了解这一过程将使我们能够制定策略，将利用硝酸盐的细菌对我们的农业土壤和更广泛的环境的影响降至最低。

Nitrogen is one of the key elements in biological systems since it is required in large quantities for the building blocks of life. Humans are rather limited in the sources of nitrogen they can use to live and grow, and we obtain nitrogen we need from complex organic compounds in the food we eat. By contrast, microbial metabolism is more adaptable and bacteria can capture the nitrogen they need from a range of simpler forms present in nature such as nitrate. In recent times, the amount of man-made nitrogen in the environment has increased dramatically due to industrial fixation of the relatively inert nitrogen gas present in the atmosphere. As the world population has grown, more intensive agricultural practices have been used to increase crop yields to meet this demand, including the widespread use of synthetic nitrate-based fertilisers in modern agricultural practice.Nitrate is highly soluble in water and readily lost from fields as run-off where it accumulates in rivers, lakes and oceans and provides an abundant nutrient for bacteria that are able to use it for growth. In agricultural fields the use of nitrate by soil microbes, instead of the crops for which it was intended, is not only economically wasteful but may also have a number of unintended consequences. One such consequence is predicted to be the increased consumption of dissolved organic carbon by particular bacteria in the environment. This poses a significant risk to the fertility and integrity of many soil types through catabolic breakdown of their organic constituents by nitrate-utilising bacterial populations. A significant decrease in soil organic matter would not only have a negative impact on the long-term sustainability of commercially valuable agricultural land, but increased microbial action on these carbon dioxide sinks may also contribute to global climate change.In this research programme we will address the role of a key gene we have identified that is essential for the use of nitrogen by the model nitrate-utilising soil bacterium Paracoccus denitrificans, which is widely studied in laboratories around the world. This gene is predicted to produce a regulatory protein that may control how bacteria use nitrate and carbon to grow. Understanding this process will enable us to develop strategies to minimise the impact of nitrate-utilising bacteria on our agricultural soils and the wider environment.