Integrative Conjugative Elements (ICE’s) of the SXT/R391 family have largely been detected in clinical or environmental isolates of Gammaproteobacteria, particularly Vibrio and Proteus species. As wastewater treatment plants accumulate a large and diverse number of such species, we examined raw water samples taken from a municipal wastewater treatment plant initially using SXT/R391 family integrase gene-specific PCR probes to detect the presence of such elements in a directed approach. A positive amplification occurred over a full year period and a subsequent Restriction Fragment Length Polymorphism (RFLP) analysis revealed a very limited diversity in the treatment plant examined. Samples demonstrating positive amplification were cultured using Vibrio and Proteus selective media and PCR amplification tracking was utilized to monitor SXT/R391-ICE family containing strains. This screening procedure resulted in the isolation and identification of a Proteus mirabilis strain harbouring an ICE. Whole-genome sequencing of this ICE containing strain using Illumina sequencing technology revealed a novel 81 kb element that contained 75 open reading frames on annotation but contained no antibiotic or metal resistance determinants. Comparative genomics revealed the element contained a conserved ICE core with one of the insertions containing a novel bacteriophage defence mechanism. This directed isolation suggests that ICE elements are present in the environment without apparent selective pressure but may contain adaptive functions allowing survival in particular environments such as municipal wastewater which are reservoirs for large bacterial phage populations.

SXT / R391家族的整合共轭元件（ICE）已在伽玛变形杆菌的临床或环境分离物中，尤其是弧菌和变形杆菌中被发现。随着废水处理厂中大量此类物种的积累，我们首先使用SXT / R391家族整合酶基因特异性PCR探针检查了从市政废水处理厂中提取的原水样品，以有针对性的方法检测此类元素的存在。整年中都发生了阳性扩增，随后的限制性片段长度多态性（RFLP）分析表明，所处理的处理厂的多样性非常有限。证明阳性扩增的样品使用Vibrio和变形杆菌选择性培养基和PCR扩增跟踪被用来监测包含SXT / R391-ICE家族的菌株。该筛选程序导致分离并鉴定了变形杆菌（Proteus mirabilis）带有ICE的应变。使用Illumina测序技术对该含ICE的菌株进行全基因组测序，发现了一个新颖的81 kb元件，该元件在注释上包含75个开放阅读框，但不包含抗生素或金属抗性决定簇。比较基因组学表明，该元件包含一个保守的ICE核心，其中一个插入片段包含新的噬菌体防御机制。这种直接隔离表明，ICE元素存在于没有明显选择压力的环境中，但可能具有适应性功能，可以在特定环境（例如市政污水）中生存，这些污水是大型细菌噬菌体种群的储存库。