The importance of nutrient ratios in determining elevations in geosmin synthase (geoA) and 2-MIB cyclase (mic) resulting in taste and odour events.
The importance of nutrient ratios in determining elevations in geosmin synthase (geoA) and 2-MIB cyclase (mic) resulting in taste and odour events.
复制标题
DOI：
10.1016/j.watres.2023.119693
复制
发表时间：
2023-02
期刊：
影响因子：
12.8
通讯作者：
A.S Hooper;P. Kille;S. Watson;S. Christofides;R. Perkins
中科院分区：
文献类型：
--
作者：
A.S Hooper;P. Kille;S. Watson;S. Christofides;R. Perkins
Geosmin合成酶(geosmin synthase，geoA)和2-mib环化酶(2-mib Cyclase，MIC)是合成味觉和气味(T&O)化合物、geosmin和2-mib的关键基因。这些T&O化合物正在成为饮用水供应的一个日益严重的全球性问题。据认为，Geosmin和2-MIB可能与各种不同的环境和营养触发因素有关，或被各种不同的环境和营养触发因素加剧。然而，就我们所知，到目前为止，还没有研究评估季节性、温度和营养浓度对地球A和M拷贝数与T&O浓度的综合影响。在这项研究中，从2019年7月到2020年8月，在英国威尔士的九个水库中调查了geosmin和2-mib生产背后的环境触发因素。通过定量聚合酶链式反应(QPCR)定量测定GeoA和GeoMIC的丰度。−1.对地气浓度升高的水库的模型分析显示，地气与平均温度(p<；0.001)、溶解活性硅酸盐(p<；0.001)、溶解铁(p<；0.001)、总无机氮与磷的比率(p<；0.001)以及氨与硝酸盐的比率(p<；−)(p<；0.001)显著相关。硫酸盐也与GeoA呈显著的线性正相关(p<；0.001)。公式分析表明，NH_4~+：NO_3~(2+)−与MIC显著相关(p<；0.05)，与溶解的活性硅酸盐也有关联(p=0.084)。在这项研究中，我们还报告了研究季节之间基因拷贝数量的极端差异。形式拷贝数m L−1和2-MiB(ng L−1)之间没有一致的关系。研究结果表明，TIN：TP和NH_4+：NO_3−是地气异常升高的良好预测因子，而平均温度和溶解活性硅酸盐则呈负线性关系。总体而言，我们的发现证明了营养浓度、营养比率和温度对饮用水水库中味觉和气味事件的循证预测能力的重要性。
Geosmin synthase (geoA) and 2-MIB cyclase (mic) are key biosynthetic genes responsible for the production of taste and odour (T&O) compounds, geosmin and 2-MIB. These T&O compounds are becoming an increasing global problem for drinking water supplies. It is thought that geosmin and 2-MIB may be linked to, or exacerbated by, a variety of different environmental and nutrient triggers. However, to the best of our knowledge, no studies to date have evaluated the combined effects of seasonality, temperature, and nutrient concentrations ongeoAandmiccopy numbers in conjunction with T&O concentrations. In this study, environmental triggers behind geosmin and 2-MIB production were investigated in nine reservoirs across Wales, U.K. between July 2019 – August 2020. The abundance ofgeoAandmicwere quantified through quantitative Polymerase Chain Reaction (qPCR). Temporal changes ingeoAand geosmin concentrations revealedgeoAto be an indicator of monthly geosmin concentrations, although only when geosmin concentrations exceeded 100 ng L−1. Model analysis of a reservoir with elevated geosmin concentrations revealedgeoAto be significantly associated with mean temperature (p< 0.001) and the nutrients dissolved reactive silicate (p< 0.001), dissolved iron (p< 0.001), total inorganic nitrogen to phosphorous ratio (TIN:TP) (p< 0.001) and ammonium to nitrate ratio (NH4+:NO3−) (p< 0.001). Sulphate also demonstrated a significant positive linear relationship withgeoA(p< 0.001). Formicanalysis, NH4+:NO3−was significantly associated withmic(p< 0.05) and an association with dissolved reactive silicate was also observed (p= 0.084). Within this study we also report extreme variance in gene copy numbers between the study seasons. No consistent relationship could be determined formiccopy numbers mL−1and 2-MIB (ng L−1). The findings from this study indicate that TIN:TP and NH4+:NO3−serve as good predictors for elevatedgeoAandmic, along with negative linear relationships observed for mean temperature and dissolved reactive silicate. Overall, our findings demonstrate the importance of nutrient concentrations, nutrient ratios and temperature for evidence based predictive capacity of taste and odour events in drinking water reservoirs.