Cai Yu-Ming
National Biofilms Innovation Centre, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
Biological Sciences, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
Front Microbiol. 2020 Dec 4;11:557035. doi: 10.3389/fmicb.2020.557035. eCollection 2020.
Bacteria are now generally believed to adopt two main lifestyles: planktonic individuals, or surface-attached biofilms. However, in recent years medical microbiologists started to stress that suspended bacterial aggregates are a major form of bacterial communities in chronic infection sites. Despite sharing many similarities with surface-attached biofilms and are thus generally defined as biofilm-like aggregates, these non-attached clumps of cells show much smaller sizes and different formation mechanisms. Furthermore, clinical isolates were frequently reported to be less attached to abiotic surfaces when compared to standard type strains. While this third lifestyle is starting to draw heavy attention in clinical studies, it has a long history in natural and environmental sciences. For example, marine gel particles formed by bacteria attachment to phytoplankton exopolymers have been well documented in oceans; large river and lake snows loaded with bacterial aggregates are frequently found in freshwater systems; multispecies bacterial "flocs" have long been used in wastewater treatment. This review focuses on non-attached aggregates found in a variety of natural and clinical settings, as well as some recent technical developments facilitating aggregate research. The aim is to summarise the characteristics of different types of bacterial aggregates, bridging the knowledge gap, provoking new perspectives for researchers from different fields, and highlighting the importance of more research input in this third lifestyle of bacteria closely relevant to our daily life.
浮游个体或附着于表面的生物膜。然而，近年来医学微生物学家开始强调，悬浮的细菌聚集体是慢性感染部位细菌群落的主要形式。尽管这些非附着的细胞团与附着于表面的生物膜有许多相似之处，因此通常被定义为类生物膜聚集体，但它们的尺寸要小得多，形成机制也不同。此外，与标准类型菌株相比，临床分离株通常被报道对非生物表面的附着性较差。虽然这种第三种生存方式在临床研究中开始受到高度关注，但在自然科学和环境科学领域它有着悠久的历史。例如，细菌附着在浮游植物胞外聚合物上形成的海洋凝胶颗粒在海洋中已有充分记载；淡水系统中经常发现含有细菌聚集体的大河和湖泊雪状物；多物种细菌“絮体”长期以来一直用于废水处理。这篇综述聚焦于在各种自然和临床环境中发现的非附着聚集体，以及一些有助于聚集体研究的最新技术进展。目的是总结不同类型细菌聚集体的特征，弥合知识差距，为不同领域的研究人员激发新的观点，并强调在这种与我们日常生活密切相关的细菌第三种生存方式上投入更多研究的重要性。
