Uncovering the Molecular Basis of Formation of Viable But Non-Culturable Cells

副溶血性弧菌是一种存在于海洋环境中的细菌，可以在海水，贝类（如牡蛎和贻贝）和甲壳类（如螃蟹）中找到。这种细菌是全球海鲜相关胃肠炎的主要原因。细菌可在烹煮过程中被破坏，因此感染通常与食用生贝类或煮熟的海鲜产品有关，这些产品已被生贝类或受污染的水交叉污染。副溶血性弧菌感染在夏季达到高峰，此时海水温度最适合其生长。在过去10年中，副溶血性弧菌的爆发数量在世界范围内增加，这是海水温度上升的结果。气候变化、全球化和其他驱动因素也使欧洲成为包括副溶血性弧菌感染在内的新兴传染病的热点地区。目前，根据欧盟的食物卫生法例，没有规定在贝类收获区和即食海鲜产品进行检测时必须检测副溶血性弧菌。此外，与副溶血性弧菌相关的疾病在欧盟是不需要通报的，但近年来在欧洲，包括西班牙、意大利和挪威，已经发生了一些与受污染的海鲜相关的疫情，这些疫情已经开始改变这种病原体在欧洲的重要性。过去的研究表明，当细菌在海水中培养时，细胞仍然“活着”，但不能在培养基上生长。然而，它们有时仍然具有致病的能力。这些细菌被称为“活的但不可培养的”（VBNC）细胞。VBNC细胞允许细菌存活，直到更有利的条件出现。处于VBNC状态的细胞具有低代谢活性，但是在环境刺激（例如温度升高或营养补充）之后，它们可以“复苏”并恢复它们在培养基上生长的能力。VBNC细胞不仅在医学方面很重要，因为它们能够在有利的条件下保持毒性和复苏，而且它们在食品安全方面也很重要。如果食品样品中存在VBNC细胞，并且无法通过常规技术检测到，则食品样品中的细菌数量可能被低估。在本项目中，我们将调查副溶血性弧菌VBNC存在于海产品中的潜在风险，以及它们可能对海产业构成的风险。我们还将试图了解副溶血性弧菌中存在的哪些基因导致这种细菌进入VBNC状态并帮助其复苏。我们的目标是帮助海产品行业想出方法来帮助管理VBNC细胞对行业构成的风险。

Vibrio parahaemolyticus is a bacterium that is present in the marine environment and can be found in seawater, shellfish (such as oysters and mussels) and in crustacea (such as crab). This bacterium is the leading cause of seafood associated gastroenteritis worldwide. The bacterium can be destroyed during the cooking process, thus infection is generally associated with eating raw shellfish or cooked seafood products that have been cross-contaminated by raw shellfish or contaminated water. V. parahaemolyticus infections peak in the summer seasons, when sea temperatures are optimum for its growth. In the last 10 years the number of V. parahaemolyticus outbreaks has increased worldwide and has been as a result of rising sea temperatures. Climate change, globalisation and other drivers have also made Europe a hot spot for emerging infectious diseases including infections by V. parahaemolyticus. At present, detection of V. parahaemolyticus is not required under EU Food Hygiene legislation for testing of shellfish harvesting areas and ready to eat seafood products. Furthermore, disease associated with V. parahaemolyticus is not notifiable in the EU but in recent years there have been a number of outbreaks associated with contaminated seafood in Europe including Spain, Italy and Norway that have begun to change the significance of this pathogen in Europe. In the past it has been shown that when bacteria were incubated in sea water, the cells remained 'alive' but could not grow on culture media. However, they sometimes retain the ability to cause disease. These bacteria have been called 'viable but non-culturable' (VBNC) cells. The VBNC cells allow the bacteria to survive, until more favourable conditions arise. Cells in the VBNC state have low metabolic activity but, following environmental stimuli such as temperature upshift or nutrient supplementation, they can 'resuscitate' and restore their ability to grow on media. VBNC cells are not just important in a medical context because of their capacity to remain virulent and resuscitate in favourable conditions but they are also important in food safety. If VBNC cells are present in food samples and cannot be detected by conventional techniques, then the number of bacteria in food samples could be underestimated. In this project we will investigate the potential risk of V. parahaemolyticus VBNC present in seafoods and the risk they may pose to the seafood industry. We will also try to understand what genes present in V. parahaemolyticus cause this bacterium to enter the VBNC state and help in its resuscitation. Our aim is to help the seafood industry come up with ways to help manage the risk VBNC cells pose to the industry.