Gomes Inês B, Lemos Madalena, Fernandes Susana, Borges Anabela, Simões Lúcia C, Simões Manuel
LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal.
CEB-Centre of Biological Engineering, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal.
Microorganisms. 2021 May 29;9(6):1174. doi: 10.3390/microorganisms9061174.
Biofilm control is mainly based on chemical disinfection, without a clear understanding of the role of the biocides and process conditions on biofilm removal. This study aims to understand the effects of a biocide (benzyldimethyldodecyl ammonium chloride-BDMDAC) and mechanical treatment (an increase of shear stress -τw) on single- and dual-species biofilms formed by and on high-density polyethene (HDPE). BDMDAC effects were initially assessed on bacterial physicochemical properties and initial adhesion ability. Then, mature biofilms were formed on a rotating cylinder reactor (RCR) for 7 days to assess the effects of chemical and mechanical treatments, and the combination of both on biofilm removal. The results demonstrated that the initial adhesion does not predict the formation of mature biofilms. It was observed that the dual-species biofilms were the most susceptible to BDMDAC exposure. The exposure to increasing τw emphasised the mechanical stability of biofilms, as lower values of τw (1.66 Pa) caused high biofilm erosion and higher τw values (17.7 Pa) seem to compress the remaining biofilm. In general, the combination of BDMDAC and the mechanical treatment was synergic in increasing biofilm removal. However, these were insufficient to cause total biofilm removal (100%; an average standard deviation of 11% for the method accuracy should be considered) from HDPE.
生物膜控制主要基于化学消毒，对杀菌剂和工艺条件在生物膜去除方面的作用缺乏清晰认识。本研究旨在了解一种杀菌剂（苄基二甲基十二烷基氯化铵 - BDMDAC）和机械处理（剪切应力增加 - τw）对由 和 在高密度聚乙烯（HDPE）上形成的单物种和双物种生物膜的影响。首先评估了BDMDAC对细菌理化性质和初始粘附能力的影响。然后，在旋转圆柱反应器（RCR）上形成成熟生物膜7天，以评估化学和机械处理以及两者结合对生物膜去除的影响。结果表明，初始粘附并不能预测成熟生物膜的形成。观察到双物种生物膜对BDMDAC暴露最为敏感。随着τw增加，生物膜的机械稳定性增强，因为较低的τw值（1.66 Pa）会导致生物膜大量侵蚀，而较高的τw值（17.7 Pa）似乎会压缩剩余的生物膜。总体而言，BDMDAC与机械处理相结合在增加生物膜去除方面具有协同作用。然而，这些方法不足以使HDPE上的生物膜完全去除（100%；应考虑该方法精度的平均标准偏差为11%）。
