Developing novel models to understand threats from Vibrio pathogens for safeguarding aquatic food supply under future climates

气候变化导致海洋变暖，正在影响影响近岸生态系统的极端天气事件的频率，强度和持续时间，这将使我们的英国沿海贝类渔业更容易受到新的和正在出现的微生物疾病的影响，并可能带来更大的相关人类健康问题。当细菌遇到极端或不利的环境条件时，它们进入休眠状态以保护自己，然而，当有利的环境条件恢复时，它们可以重新唤醒。对于细菌病原体，这些重新出现的水华可能对环境有害，在某些情况下对人类健康有害。预防细菌性疾病的一个主要问题是休眠细胞无法通过常规测试检测到，这使得它们难以研究。在这个项目中，我们将探索新的方法来理解（机制）通过休眠细菌弧菌细胞（我们的研究生物）在环境中作为活跃的致病病原体出现，为未来预测和预防野生贝类渔业和养殖贝类中弧菌病建立的项目提供了一个跳板，弧菌病是一种在管理的和野生的贝类渔业中造成许多大规模死亡事件的疾病，并且在全球范围内，弧菌病原体是人类海产品相关胃肠炎的主要原因。副溶血性弧菌在本港沿岸沃茨、沉积物及贝壳类海产中，于夏季出现，但在冬季则没有发现。人们一直认为这些细菌是由于冷水温度而死亡的，然而，我们现在知道，一小部分细菌进入休眠状态，以便在较冷的（冬季）条件下生存。当夏季条件恢复时，营养水平和海水温度增加，这些休眠细胞重新唤醒，生长成细菌种群，可以感染贝类并对人类健康造成不利影响。在这个项目中，我们将首先检测和量化弧菌在其各种功能状态的水，沉积物和贝类的环境非生物因素在英国多塞特郡的沿海网站。我们将应用的细胞分选和染色方法将使我们能够将休眠的弧菌细胞群与代谢活性和非活性的弧菌细胞群分开。然后，我们将通过操纵盐和温度以模拟夏季条件并添加乳酸钠来评估复苏从环境样品中收集的休眠细胞的能力（我们已经证明乳酸盐可以复苏我们实验室诱导的休眠细胞的弧菌休眠细胞）。我们还将通过将来自我们的环境样品的复苏的弧菌细胞注射到已建立的蛾幼虫疾病模型中来测试其毒力潜力。最后，我们将开发分析方案（使用质谱分光光度法），以确定乳酸在环境休眠细胞中的命运，并确定休眠细胞转换为活跃生长的细胞群的代谢机制。总的来说，这些研究将是向前迈出的重要一步，有助于确定使弧菌细胞从休眠中出现并在有利的气候条件下形成不断增长的种群以引起疾病的因素。提高我们预测弧菌细菌种群何时建立的能力，将有助于通过采取缓解策略（如净化贝类和/或早期和/或选择性收获）来预防疾病再感染和避免季节性流行病。

Climate change, leading to ocean warming, is affecting the frequency, intensity and duration of extreme weather events affecting nearshore ecosystems that will make our UK coastal shellfisheries more vulnerable to new and emerging microbial diseases, and with potentially greater associated human health concerns. When bacteria encounter extreme or unfavourable environmental conditions they enter a state of dormancy to protect themselves, however, they can re-awaken when favourable environmental conditions return. For bacterial pathogens these re-emergent blooms can be hazardous to the environment and in some cases to human health. A major problem in the prevention of bacterial diseases is that dormant cells are not detectable by routine tests making them difficult to study. In this project, we will exploit new approaches to understand the ways (mechanisms) by which dormant bacterial Vibrio cells (our study organism) emerge as active disease-causing pathogens in the environment to provide a springboard for future projects for predicting and preventing Vibrio disease establishment in wild shellfisheries and farmed shellfish, and the protection of human health.Vibriosis is a disease responsible for numerous mass mortality events in managed and wild shellfisheries, and globally Vibrio pathogens are the leading causes of seafood related gastroenteritis in humans. In our coastal waters, sediment and shellfish, Vibrio parahaemolyticus is found during the summer months but is not detected in the winter. It had been assumed that these bacteria die due to the cold-water temperatures, however, we know now that a small proportion enter dormancy in order to survive cooler (winter) conditions. When summer conditions return and, nutrient levels and sea temperatures increase these dormant cells reawaken, growing into bacterial populations that can infect shellfish and cause adverse human health impacts. In this project, we will first detect and quantify Vibrio in its various functional states in relation to environmental abiotic factors in water, sediment, and shellfish from a coastal site in Dorset, England. The cell sorting and staining methods we will apply, will allow us to separate dormant Vibrio cell populations from those that are metabolically active and those that are non-viable. We will then assess the ability to resuscitate the dormant cells collected from the environmental samples through manipulating the salt and temperature to simulate summer conditions and with the addition of sodium lactate (we have shown that lactate can resuscitate Vibrio dormant cells for our laboratory induced dormant cells). We will also test the virulence potential of the resuscitated Vibrio cells derived from our environmental samples through their injection to an established moth larvae disease model. Finally, we will develop analytical protocols (using mass spectrophotometry methods) to determine the fate of lactate in environmental dormant cells and identify metabolism mechanisms as the dormant cells switch to the actively growing cell population. Collectively these studies will be a major step forward in establishing the factors that allow Vibrio cells to emerge from dormancy and establish as a growing population under favourable climate conditions to cause disease. Improving our ability to predict when Vibrio bacterial populations are established will help prevent disease reinfections and avoidance of seasonal epidemics through adoption of mitigation strategies such as depuration of the shellfish, and/or early and/or selective harvesting.