The ecology of protist associated human pathogens

人类病原体在环境中的生存是一个正在研究的领域，通常认为病原体在哺乳动物或脊椎动物宿主之外死亡或衰老。然而，越来越明显的是，人类病原体与原生动物形成了联系，原生动物是在所有自然环境中发现的单细胞微生物，与多细胞生物体的关系比与细菌的关系更密切。它们在微生物食物网中扮演着关键角色，它们以细菌为食，并回收营养物质。原生动物还以更复杂的方式与细菌和病毒相互作用。棘阿米巴属的物种会导致严重的眼部感染、阿米巴角膜炎，以及更罕见的皮肤和中枢神经系统感染。棘阿米巴还被发现含有人类病原体，包括军团菌、衣原体、分枝杆菌、李斯特氏菌，以及一种新出现的人类病原体--巨型病毒--米米病毒。初步研究表明，在经过处理的污水污泥中有大量棘阿米巴种群，每年有100万吨棘阿米巴被处置到英国。其中一个分离株含有Mimi病毒，这是一种新出现的人类病原体，也是已知的最大病毒，以前只分离到过两次。此外，土壤和沉积物分离株还含有新的衣原体和军团菌。这项拟议的研究旨在调查与原生动物有关的土壤和水生沉积物中的人类病原体，并将评估污水污泥和废水处理废水对阿米巴相关病原体生态的影响。依赖培养和独立的方法将用于评估阿米巴和相关的细菌和病毒病原体的丰度和多样性。高通量测序将用于评估相关分枝杆菌病原体的多样性，并将其与散装土壤/沉积物中的多样性进行比较。以前在这一领域的工作是高度分散的，这项研究将是第一批尝试和阐明不同污染和未污染环境中一系列阿米巴相关病原体的丰度和多样性的研究之一。

The survival of human pathogens in the environment is an under studied area, and it is often assumed that pathogenic bacteria die or become senescent outside mammalian or vertebrate hosts. However, it is becoming clear that human pathogens form associations with protozoa which are single celled microorganisms found in all natural environments that are more closely related to multicellular organisms than to bacteria. They play a key role in microbial food webs, grazing on bacteria and recycling nutrients. Protozoa also interact with bacteria and viruses in more complex ways. Species of the genus Acanthamoeba are responsible for a serious eye infection, amoebic keratitis, and more rarely infections of the skin and central nervous system. Acanthamoebae have also been shown to harbour human pathogens including Legionella sp., Chlamydia sp., Mycobacterium sp., Listeria sp., and the giant virus, Mimivirus, which is an emerging human pathogen. Preliminary research demonstrated an abundant population of acanthamoebae in treated sewage sludge, >1 million tons of which are disposed of to land in the UK each year. One isolate harboured Mimivirus, an emerging human pathogen and the largest known virus which has only been isolated twice before. Further soil and sediment isolates harboured novel Chlamydia and Legionella sp.. The proposed research seeks to investigate human pathogens in soil and aquatic sediments associated with protozoa, and will assess the impacts of sewage sludge and waste water treatment effluent on the ecology of amoeba associated pathogens. Culture dependent and independent methods will be used to assess abundance and diversity of amoebae and associated bacterial and viral pathogens. High throughput sequencing will be used to assess diversity of associated mycobacterial pathogens and compare this to their diversity in bulk soil / sediment. Previous work in this area is highly fragmented and this study would be one of the first to try and elucidate the abundance and diversity of a range of amoeba associated pathogens in different polluted and unpolluted environments.