Phage-problem organism dynamics in biological wastewater treatment

噬菌体是一种专性寄生虫，需要原核宿主的代谢机制才能繁殖。它们在微生物群落的生态学和进化中起着至关重要的作用，影响着自然和工程系统中的细菌丰度和多样性、群落组成和功能。尽管了解噬菌体在海洋系统中的作用，但仍然缺乏对它们如何影响废水处理的理解。噬菌体在生物废水处理（BWT）中大量存在，而细菌是处理的主要代理人，是它们的宿主。因此，在BWT中的作用，在其对细菌财团的影响，以及随后，它们如何影响处理后的污水的质量，正在受到越来越多的关注。噬菌体活性可以促进系统内的生物量和生产力，但它也可以通过关键功能生物体的丧失（例如，氨和负责氨去除的亚硝酸盐氧化细菌）。事实上，阐明的作用的关键功能组和他们的时间动态和相互作用，可以帮助预测过程中的性能和系统故障，并促进潜在的使用的噬菌体作为biocontrolagents.The裂解他们的细菌宿主的能力提供了一个机会，他们使用的工具来控制微生物群落动态，类似于噬菌体治疗传染病。BWT中存在许多问题生物;例如，膨胀和起泡生物的过度生长会阻碍二次澄清;不能将硝酸盐完全转化为氮气的澄清剂会释放一氧化二氮，一种潜在的温室气体;糖原积累生物（GAO）与聚磷生物（PAO）竞争，并可能导致强化生物除磷（EBPR）的恶化;亚硝酸盐氧化细菌（NOB）可以抑制部分亚硝酸盐-安南莫（PNA）过程，甚至可以抑制工艺废水中对三级处理有抗性的病原生物的释放。因此，本博士旨在更好地了解BWT中的噬菌体，并评估其在生物控制问题生物方面的潜在用途。该项目将涉及（i）开发不依赖培养的方法，通过将病毒标记与活荧光激活细胞分选（FACS）相结合，识别和分离活性污泥系统中问题生物体的病毒，（ii）全面系统中病毒-问题宿主对的时间监测，（iii）估计来自全规模系统的问题生物的捕食率，以及（iv）培养和孵育实验，以评估分离的噬菌体作为对问题生物体的干预的有效性。

Bacteriophages, or phages, are obligate parasites that require the metabolic machinery of their prokaryotic hosts to reproduce. They play an essential role in the ecology and evolution of microbial communities, influencing bacterial abundance and diversity, community composition and function, both in natural and engineered systems. Despite knowledge of the role of phages in marine systems, an understanding of how they influence wastewater treatment is still lacking.Phages are abundant in biological wastewater treatment (BWT), and bacteria, the primary agents of treatment, are their hosts. Consequently, the role phages play in BWT, in terms of their impact on the bacterial consortia and, subsequently, how they can influence the quality of treated effluent, is receiving increased attention. Phage activity can promote biomass and productivity within a system, but it can also lead to failures through the loss of key functional organisms (e.g., ammonia and nitrite oxidising bacteria responsible for ammonia removal). Indeed, elucidating the role of phages on key functional groups and their temporal dynamics and interactions could help predict process performance and system failures and facilitate the potential use of phages as biocontrol agents.The ability of phage to lyse their bacterial hosts offers an opportunity for their use as tools to control microbial community dynamics, analogous to phage therapy in infectious diseases. Numerous problem organisms exist in BWT; for example, the overgrowth of bulking and foaming organisms can hinder secondary clarification; denitrifiers unable to perform the complete conversion of nitrate to nitrogen gas can release nitrous oxide, a potent greenhouse gas; glycogen-accumulating organisms (GAO) compete with phosphate-accumulating organisms (PAO) and can lead to the deterioration of the enhanced biological phosphorus removal (EBPR); nitrite oxidising bacteria (NOB) can supress partial nitritation-annamox (PNA) process; or even the release of pathogenic organisms resistant to tertiary treatment in process effluents.Therefore, this PhD aims to gain a greater understanding of bacteriophages in BWT and assess their potential use in the biocontrol of problem organisms. This project will involve (i) the development of culture-independent methods to identify and isolate viruses of problem organisms in activated sludge systems by combining viral tagging with live fluorescence-activated cell sorting (FACS), (ii) the temporal monitoring of virus-problem host pairs in full-scale systems, (iii) the estimation of predation rates of problem organisms from the full-scale systems and (iv) culturing and incubation experiments to assess the effectiveness of isolated bacteriophage as an intervention against problem organisms.