Cochran W L, McFeters G A, Stewart P S
Department of Microbiology, Center for Biofilm Engineering, Montana State University, Bozeman 59717, USA.
J Appl Microbiol. 2000 Jan;88(1):22-30. doi: 10.1046/j.1365-2672.2000.00825.x.
Pseudomonas aeruginosa attached to alginate gel beads in sparse, thin biofilms exhibited reduced susceptibility to monochloramine and hydrogen peroxide compared with planktonic cells of the same micro-organism. Disinfection rate coefficients for planktonic bacteria averaged 0.551 mg(-1)min(-1) for monochloramine and 3.1 x 10(-4)l mg(-1) min(-1) for hydrogen peroxide. The corresponding values for 24-h-old biofilm cells were 0.291 mg min(-1) and 9.2 x 10(-5) 1 mg(-1) min(-1) for monochloramine and hydrogen peroxide, respectively. Several pieces of evidence support the interpretation that the reduced susceptibility of biofilm was not due simply to inadequate delivery of the antimicrobial agent to the local environment of the attached cells. No correlation between biofilm susceptibility and biofilm initial areal cell density was observed. Rapid delivery of hydrogen peroxide to the attachment surface, and subsequently to the interior, of the alginate gel beads was visualized by a direct experimental technique. Theoretical analysis of unsteady diffusion and diffusion reaction interactions also argued against any significant delay or barrier to antimicrobial or oxygen delivery. It was hypothesized that new genes are expressed when bacteria attach to a surface and begin to form a biofilm and that some of the resulting gene products reduce the susceptibility of the cell to antimicrobial agents including oxidative biocides such as monochloramine and hydrogen peroxide.
与相同微生物的浮游细胞相比，附着在藻酸盐凝胶珠上形成稀疏、薄生物膜的铜绿假单胞菌对一氯胺和过氧化氢的敏感性降低。浮游细菌对一氯胺的消毒速率系数平均为0.551 mg⁻¹min⁻¹，对过氧化氢为3.1×10⁻⁴ l mg⁻¹ min⁻¹。24小时龄生物膜细胞对一氯胺和过氧化氢的相应值分别为0.291 mg min⁻¹和9.2×10⁻⁵ 1 mg⁻¹ min⁻¹。有几条证据支持这样的解释，即生物膜敏感性降低并非仅仅是由于抗菌剂向附着细胞局部环境的递送不足。未观察到生物膜敏感性与生物膜初始单位面积细胞密度之间的相关性。通过直接实验技术观察到过氧化氢迅速递送至藻酸盐凝胶珠的附着表面，随后进入其内部。对非稳态扩散和扩散反应相互作用的理论分析也反对抗菌剂或氧气递送存在任何显著延迟或障碍的观点。据推测，当细菌附着于表面并开始形成生物膜时会表达新基因，并且一些由此产生的基因产物会降低细胞对抗菌剂的敏感性，包括对一氯胺和过氧化氢等氧化型杀菌剂的敏感性。
