ENVIRONMENTAL TRIGGERS FOR GEOSMIN PRODUCTION IN FRESHWATER ECOSYSTEMS

该项目将确定触发蓝藻产生味道和气味问题代谢物1,10-二甲基反式-9-癸酚（土臭素）的触发因素。土臭素是一种主要由蓝藻产生的代谢物。它是一种天然化合物，会给饮用水带来令人不快的泥土味和/或霉味，导致客户拒绝产品和投诉。为了防止这种情况，最终处理后的水要使用活性炭过滤去除这些化合物，成本高昂，每个水处理厂每天的成本高达1500英镑。据估计，味道和气味问题每年给英国水务行业造成的损失超过2亿英镑（饮用水监察局，DWI）。该项目将提供土臭素生产触发机制模型，这将推动基于证据的湖泊和水库管理。土臭素是由蓝藻在甲羟戊酸（MV）和2-甲基赤藓糖醇-4-磷酸异戊二烯（MEP）代谢途径中产生的。它是蓝藻中一系列重要细胞化合物的前体，包括光合色素。威尔士水系PI最近的工作已经确定，土臭素的产生是蓝藻在暴露于减少或低浓度的硝酸盐和增加或高浓度的铵时快速生长阶段的结果。这可以解释为铵是最具生物可利用性的氮(N)组分，是水生系统中还原程度最高的形式。该项目将使用三个试验点来确定蓝藻合成土臭素的营养触发因素：PI已经研究了Pentwyn和Pontsticill水库和Llwyn-Onn水库，已知的生产土臭素的地点和记录的蓝藻分类群包括Dolichospermum和Oscillatoria，两者都是已知的土臭素生产者。作为PI和威尔士水的味道和气味调查的一部分，每个地点的水化学都进行了研究。因此，测试地点提供了理想的样品来源，以测试营养供应和土臭素合成酶活性之间的机制途径，从而产生土臭素。

This project will determine the triggers initiating cyanobacterial production of taste and odour problem metabolite, 1,10-dimethyl-trans-9-decalol (geosmin). Geosmin is a metabolite produced in drinking water supply reservoirs primarily by cyanobacteria. It is a natural compound that results in an unpleasant earthy and/or musty taste to drinking water, resulting in customer product rejection and complaints. To prevent this, final treated water undergoes costly removal of these compounds using activated carbon filtration, at a cost of up to £1,500 per day per water treatment works. Taste and odour issues are estimated to cost the UK Water industry over £200 million per annum (Drinking Water Inspectorate, DWI). This project will deliver a mechanistic model of the triggers for geosmin production that will drive evidence based management of lakes and reservoirs. Geosmin is produced by cyanobacteria in the mevalonate (MV) and 2-methylerythritol-4-phosphate isoprenoid (MEP) metabolic pathways. It is a precursor for a range of important cellular compounds in cyanobacteria, including photosynthetic pigments. Recent work by the PI within Welsh Water has determined that geosmin production is the result of periods of rapid growth phase by cyanobacteria when exposed to reducing or low concentrations of nitrate and increasing or high concentrations of ammonium. This can be explained as ammonium is the most biologically available nitrogen (N) fraction, being the most reduced form in aquatic systems. This project will use three test sites to determine nutrient triggers for geosmin synthesis by cyanobacteria: Pentwyn and Pontsticill reservoirs and Llwyn-Onn reservoir have been studied by the PI and are known sites with geosmin production and cyanobacteria taxa recorded include Dolichospermum and Oscillatoria, both known geosmin producers. The water chemistry at each site has been studied as part of a taste and odour investigation by the PI and Welsh Water. The test sites therefore provide ideal sources for samples to test for a mechanistic pathway between nutrient supply and geosmin synthetase activity and hence geosmin production.