Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
Microbiol Spectr. 2021 Oct 31;9(2):e0110521. doi: 10.1128/Spectrum.01105-21. Epub 2021 Oct 27.
Porous media filters are used widely to remove bacteria from contaminated water, such as stormwater runoff. Biofilms that colonize filter media during normal function can significantly alter performance, but it is not clear how characteristics of individual populations colonizing porous media combine to affect bacterial retention. We assess how four bacterial strains isolated from stormwater and a laboratory strain, Pseudomonas aeruginosa PAO1, alter Escherichia coli retention in experimental sand columns under conditions of stormwater filtration relative to a clean-bed control. Our results demonstrate that these strains differentially affect E. coli retention, as was previously shown for a model colloid. To determine whether E. coli retention could be influenced by changes in relative abundance of strains within a microbial community, we selected two pairs of biofilm strains with the largest observed differences in E. coli retention and tested how changes in relative abundance of strain pairs in the biofilm affected E. coli retention. The results demonstrate that E. coli retention efficiency is influenced by the retention characteristics of the strains within biofilm microbial community, but individual strain characteristics influence retention in a manner that cannot be determined from changes in their relative abundance alone. This study demonstrates that changes in the relative abundance of specific members of a biofilm community can significantly alter filter performance, but these changes are not a simple function of strain-specific retention and the relative abundance. Our results suggest that the microbial community composition of biofilms should be considered when evaluating factors that influence filter performance. The retention efficiency of bacterial contaminants in biofilm-colonized biofilters is highly variable. Despite the increasing number of studies on the impact of biofilms in filters on bacterial retention, how individual bacterial strains within a biofilm community combine to influence bacterial retention is unknown. Here, we studied the retention of an E. coli K-12 strain, as a model bacterium, in columns colonized by four bacterial strains isolated from stormwater and P. aeruginosa, a model biofilm-forming strain. Simplified two-strain biofilm communities composed of combinations of the strains were used to determine how relative abundance of biofilm strains affects filter performance. Our results provide insight into how biofilm microbial composition influences bacterial retention in filters and whether it is possible to predict bacterial retention efficiency in biofilm-colonized filters from the relative abundance of individual members and the retention characteristics of cultured isolates.
多孔介质过滤器广泛用于去除受污染水中的细菌，例如雨水径流。在正常功能期间，生物膜会在过滤介质上定殖，这会显著改变其性能，但目前尚不清楚定殖多孔介质的各个种群的特征如何组合来影响细菌截留。我们评估了从雨水和实验室分离的四种细菌菌株以及实验室菌株铜绿假单胞菌 PAO1 在雨水过滤条件下对实验砂柱中大肠杆菌截留的影响，与清洁床对照相比。我们的结果表明，这些菌株会以与模型胶体先前显示的不同方式影响大肠杆菌的截留。为了确定微生物群落中菌株的相对丰度变化是否会影响大肠杆菌的截留，可以选择两对生物膜菌株，它们在大肠杆菌截留方面表现出最大的差异，并测试生物膜中菌株对的相对丰度变化如何影响大肠杆菌的截留。结果表明，大肠杆菌的截留效率受到生物膜微生物群落中菌株截留特性的影响，但单个菌株特性的影响方式不能仅通过其相对丰度的变化来确定。这项研究表明，生物膜群落中特定成员的相对丰度变化会显著改变过滤器的性能，但这些变化不是菌株特异性截留和相对丰度的简单函数。我们的结果表明，在评估影响过滤器性能的因素时，应考虑生物膜的微生物群落组成。 生物膜定殖生物过滤器中细菌污染物的截留效率高度可变。尽管越来越多的研究关注生物膜在过滤器中对细菌截留的影响，但生物膜群落中单个细菌菌株如何组合来影响细菌截留仍不清楚。在这里，我们研究了作为模型细菌的大肠杆菌 K-12 菌株在由从雨水分离的四种细菌菌株和铜绿假单胞菌组成的生物膜定殖的柱子中的截留，铜绿假单胞菌是一种模型生物膜形成菌株。使用简化的两菌株生物膜群落来确定生物膜菌株的相对丰度如何影响过滤器性能。我们的结果提供了对生物膜微生物组成如何影响过滤器中细菌截留的深入了解，以及是否可以从单个成员的相对丰度和培养分离株的截留特性来预测生物膜定殖过滤器中的细菌截留效率。
