Abstract

The effect that the hydrodynamic conditions under which biofilms are formed has on their persistence is still unknown. This study assessed the behaviour of Pseudomonas fluorescens biofilms, formed on stainless steel under different shear stress (${\mathrm{\tau }}_{\mathrm{w}}$) conditions (1, 2 and 4 Pa), to chemical (benzalkonium chloride – BAC, glutaraldehyde – GLUT and sodium hypochlorite – SHC) and mechanical (20 Pa) treatments (alone and combined). The biofilms formed under different ${\mathrm{\tau }}_{\mathrm{w}}$ showed different structural characteristics. Those formed under a higher ${\mathrm{\tau }}_{\mathrm{w}}$ were invariably more tolerant to chemical and mechanical stresses. SHC was the biocide which caused the highest biofilm killing and removal, followed by BAC. The sequential exposure to biocides and mechanical stress was found to be insufficient for effective biofilm control. A basal layer containing biofilm cells mostly in a viable state remained on the surface of the cylinders, particularly for the 2 and 4 Pa-generated biofilms.

摘要

形成生物膜的流体动力学条件对其持久性的影响仍然未知。本研究评估了在不同剪切应力下在不锈钢上形成的荧光假单胞菌生物膜的行为。${\mathrm{\tau }}_{\mathrm{w}}$) 条件（1、2 和 4  Pa）、化学（苯扎氯铵 – BAC、戊二醛 – GLUT 和次氯酸钠 – SHC）和机械（20  Pa）处理（单独和组合）。不同条件下形成的生物膜${\mathrm{\tau }}_{\mathrm{w}}$表现出不同的结构特征。那些在更高层次下形成的${\mathrm{\tau }}_{\mathrm{w}}$总是更能耐受化学和机械应力。SHC 是生物膜杀灭和去除率最高的杀菌剂，其次是 BAC。发现连续暴露于杀生物剂和机械应力不足以有效控制生物膜。含有大部分处于存活状态的生物膜细胞的基底层保留在圆柱体的表面上，特别是对于 2 和 4  Pa 生成的生物膜。