Effect of temperature conditions on the growth of Legionella species in complex biological systems for wastewater treatment

致病性军团菌与嗜肺军团菌一样，可引起军团病，这是一种严重的肺部感染，死亡率为5-10%。它是通过吸入人造水系统（如废水处理厂）污染的气溶胶传播的。从2015年到2019年，欧洲的军团病病例增加了65%。由于废水再利用的增加和气候变化，来自废水处理厂的军团病病例预计将增加。后者尤其会增加废水温度，也会影响废水的微生物组成。据我们所知，由于缺乏基础研究，目前还没有一种解决方案可以防止军团菌在废水温度较高（bbb23°C）的污水处理厂中繁殖。本提案的目的是确定有利于从污水处理厂致病军团菌生长的温度条件，考虑恒定和动态温度条件。从处理过的废水或五个不同废水处理厂的活性污泥中获得的分离物，处理工业暖废水，将在20°C至40°C之间的五个不同温度下培养。为了测试动态温度条件的影响，在指数生长阶段的中期，在短时间内将温度升高5℃。将比较摄动前后军团菌的生长参数。根据我们在污水处理厂监测军团菌的经验，选择了5℃的快速升温。采用培养法分离环境军团菌。环境分离株的隶属关系和军团菌在生物阶段的多样性将通过属特异性下一代测序进行分析。温度实验的分离株将选择涵盖所有五个污水处理厂中存在的核心军团菌群落，以及仅存在于特定废水处理厂的独特种型。综合废水/废水处理厂特征，军团菌多样性和军团菌环境分离物的温度依赖性生长的结果将促进我们对废水处理厂作为军团菌生长的生态位的作用的理解。我们的研究结果可用于改善废水处理厂的军团菌监测，并支持从业者制定管理废水处理和回收设施中温度突然变化的策略。

Pathogenic Legionella spp., like Legionella pneumophila, can cause Legionnaire’s disease, a severe lung infection with a mortality of 5-10%. It is transmitted by the inhalation of contaminated aerosols from man-made water systems, such as wastewater treatment plants. Cases of Legionnaires’ disease increased in Europe by 65 % from 2015 to 2019. Legionnaires’ disease cases originating from wastewater treatment plants are expected to increase due to increased wastewater reuse applications and Climate Change. The latter in particular will increase wastewater temperatures, affecting also the microbial composition of wastewaters. To the best of our knowledge, a solution to prevent the multiplication of Legionella in wastewater treatment plants with warm wastewater temperatures (>23°C) is not available due to the lack of fundamental research. The objective of this proposal is to define the temperature conditions favouring the growth of pathogenic Legionella spp. from wastewater treatment plants, considering constant and dynamic temperature conditions.Isolates obtained from treated wastewater or activated sludge of five different wastewater treatment plants, treating industrial warm wastewaters, will be cultivated at five different temperatures between 20 °C and 40 °C. To test the effect of dynamic temperature conditions the temperature will be increased by 5 °C in a short time in the middle of the exponential growth phase. The Legionella’s growth parameters will be compared before and after the perturbation. A fast temperature increase of 5 °C was chosen according to our experience in monitoring Legionella spp. in wastewater treatment plants. The environmental Legionella isolates will be obtained, using the cultivation method. The affiliation of the environmental isolates and the Legionella spp. diversity in the biological stage will be analysed by genus-specific next-generation sequencing. Isolates for the temperature experiment will be selected covering the core Legionella community, present in all five wastewater treatment plants, and the unique phylotypes, only present in specific wastewater treatments plants.The integration of the results coming from the wastewater/wastewater treatment plant characterisation, the Legionella diversity and the temperature-dependent growth of Legionella environmental isolates from wastewater will advance our understanding of the role of wastewater treatment plants as an ecological niche for the growth of Legionella spp. . Our findings may be used to improve Legionella monitoring in wastewater treatment plants and to support the practitioners in the development of strategies to manage with sudden changes in temperature in wastewater treatment and reclamation facilities.