Control of Listeria monocytogenes in the fresh produce supply chain. Industry-match funded project 3

新鲜农产品(沙拉和草药)被认为是健康营养饮食所必需的，但在农场和工厂可能会受到环境污染。由于新鲜农产品没有煮熟，潜在的健康风险加剧。特别令人关注的是新鲜农产品受到单核细胞增多性李斯特氏菌的污染，这是一种只导致少量食源性疫情的病原体，但它会导致严重的胃肠道感染，对免疫功能低下的患者来说可能是极其虚弱的，导致孕妇流产，并且是所有主要食源性病原体中死亡率最高的。它广泛存在于土壤和水中，可以在一系列温度下生长，包括食品加工和储存中发现的4摄氏度的低温。我们展示了它在温度范围内形成单一培养生物膜，并根据营养物质的可获得性、温度和消毒压力而变得有活力但不可培养(VBNC)。VBNC表型意味着使用ISO批准的金标准培养回收方法会遗漏VBNC的存在，如果食品被认为不含病原体，则会带来公共卫生风险。对其在食品供应链中存在的多菌生物膜群落(微生物群)中生存的能力以及相互作用如何支持病原体持久性、抗菌素耐药性(包括对食品行业经常使用的消毒剂)以及在有或没有消毒剂的情况下VBNC的状态知之甚少。其目的是：开发适当的样品回收和分子方法来检测供应链关键点的微生物群和可培养的和VBNC L.单核细胞增多症。确定支持单核细胞增多性李斯特菌在供应链中持续存在的可能的协同或拮抗作用。使用适当的工厂微生物生物膜和单核细胞增多性乳杆菌的实验室模型，为工厂清洁确定适当的消毒程序。通过现场工厂测试合适的消毒剂来验证实验室研究，以确定实际生活中的安全操作条件。

Fresh produce (salads and herbs) are considered essential for a healthy nutritious diet but may be exposed to environmental contamination in the farm and factory. Potential health risk is exacerbated due to fresh produce not being cooked. Of particular concern is contamination of fresh produce with Listeria monocytogenes, a pathogen responsible for only a small number of foodborne outbreaks but it causes a serious gastrointestinal infection which can be extremely debilitating for immunocompromised patients, causes miscarriage in pregnant women and has the highest mortality of all the major foodborne pathogens. It is widely found in soil and water and can grow over a range of temperatures, including chill temperatures of 4oC which are found in food processing and storage. We showed it forms monoculture biofilms over the temperature range and can become viable but nonculturable (VBNC) depending on nutrient availability, temperature and disinfection stress. The VBNC phenotype means that its presence is missed using the ISO approved, gold standard culture recovery methods, presenting a public health risk if food is deemed free of pathogens. Little is known about its ability to survive in polymicrobial biofilm communities (microbiomes) present in food supply chains and how interactions may support pathogen persistence, antimicrobial resistance including to sanitisers regularly used by the food industry, and the VBNC state in the presence or absence of sanitisers. The aims are: Develop appropriate sample recovery and molecular methods to detect microbiomes and culturable and VBNC L. monocytogenes at critical points in the supply chain. Determine possible synergistic or antagonistic interactions in supporting L. monocytogenes persistence in the supply chain. Determine appropriate sanitisation procedures for factory cleaning using appropriate laboratory models of factory biofilms of microbiomes and L. monocytogenes. Validate lab studies with on-site factory testing of suitable sanitisers to determine real life safe operating conditions.