Lynch Martin J, Swift Simon, Kirke David F, Keevil C William, Dodd Christine E R, Williams Paul
Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK.
Environ Microbiol. 2002 Jan;4(1):18-28. doi: 10.1046/j.1462-2920.2002.00264.x.
Aeromonas hydrophila is an opportunistic Gram-negative pathogen that readily attaches to stainless steel to produce a thin biofilm with a complex 3D structure covering 40-50% of the available surface and producing large microcolonies. As A. hydrophila possesses an N-acylhomoserine lactone (AHL)-dependent quorum-sensing system based on the ahyRI locus, the presence of the AhyI protein and C4-HSL within the biofilm phase was first established by Western blot and AHL biosensor analysis respectively. The ability of the A. hydrophila AH-1 N strain to form biofilms in a continuous-flow chamber was compared with isogenic ahyI and ahyR mutants. The ahyI mutant, which cannot produce C4-HSL, failed to form a mature biofilm. In addition, the viable count of biofilm, but not planktonic phase ahyI mutants, was significantly lower that the parent or ahyR mutant. This defect in the differentiation of the ahyI mutant biofilm could be partially restored by the addition of exogenous C4-HSL. A mutation in ahyR increased coverage of the available surface to around 80% with no obvious effect upon biofilm microcolony formation. These data support a role for AHL-dependent quorum sensing in A. hydrophila biofilm development. Exposure of the A. hydrophila AH-1N biofilm to N-(3-oxodecanoyl)homoserine lactone, which inhibits exoprotease production in planktonic cells, however, had no effect on biofilm formation or architecture within the continuous-flow chamber.
嗜水气单胞菌是一种机会性革兰氏阴性病原体，它很容易附着在不锈钢上，形成一层薄的生物膜，该生物膜具有复杂的三维结构，覆盖了40%-50%的可用表面，并产生大型微菌落。由于嗜水气单胞菌拥有基于ahyRI基因座的N-酰基高丝氨酸内酯（AHL）依赖性群体感应系统，因此首先分别通过蛋白质免疫印迹法和AHL生物传感器分析确定了生物膜阶段中AhyI蛋白和C4-HSL的存在。将嗜水气单胞菌AH-1 N菌株在连续流动室中形成生物膜的能力与同基因的ahyI和ahyR突变体进行了比较。不能产生C4-HSL的ahyI突变体无法形成成熟的生物膜。此外，生物膜中的活菌数，而非浮游阶段的ahyI突变体，显著低于亲本或ahyR突变体。通过添加外源性C4-HSL，ahyI突变体生物膜分化中的这种缺陷可以部分恢复。ahyR中的突变使可用表面的覆盖率增加到约80%，对生物膜微菌落的形成没有明显影响。这些数据支持了AHL依赖性群体感应在嗜水气单胞菌生物膜形成过程中的作用。然而，将嗜水气单胞菌AH-1N生物膜暴露于N-（3-氧代癸酰基）高丝氨酸内酯中，该物质可抑制浮游细胞中外蛋白酶的产生，但对连续流动室内生物膜的形成或结构没有影响。
