Wiencek K M, Fletcher M
Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore 21202, USA.
J Bacteriol. 1995 Apr;177(8):1959-66. doi: 10.1128/jb.177.8.1959-1966.1995.
The attachment of bacteria to solid surfaces is influenced by substratum chemistry, but to determine the mechanistic basis of this relationship, homogeneous, well-defined substrata are required. Self-assembled monolayers (SAMs) were constructed from alkanethiols to produce a range of substrata with different exposed functional groups, i.e., methyl and hydroxyl groups and a series of mixtures of the two. Percentages of hydroxyl groups in the SAMs and substratum wettability were measured by X-ray photoelectron spectroscopy and contact angles of water and hexadecane, respectively. SAMs exhibited various substratum compositions and wettabilities, ranging from hydrophilic, hydroxyl-terminated monolayers to hydrophobic, methyl-terminated monolayers. The kinetics of attachment of an estuarine bacterium to these surfaces in a laminar flow chamber were measured over periods of 120 min. The initial rate of net adhesion, the number of cells attached after 120 min, the percentage of attached cells that adsorbed or desorbed between successive measurements, and the residence times of attached cells were quantified by phase-contrast microscopy and digital image processing. The greatest numbers of attached cells occurred on hydrophobic surfaces, because (i) the initial rates of adhesion and the mean numbers of cells that attached after 120 min increased with the methyl content of the SAM and the contact angle of water and (ii) the percentage of cells that desorbed between successive measurements (ca. 2 min) decreased with increasing substratum hydrophobicity. With all surfaces, 60 to 80% of the cells that desorbed during the 120-min exposure period had residence times of less than 10 min, suggesting that establishment of firm adhesion occurred quickly on all of the test surfaces.
细菌在固体表面的附着受基质化学性质的影响，但要确定这种关系的机制基础，则需要均匀、明确的基质。由烷硫醇构建自组装单分子层（SAMs），以产生一系列具有不同暴露官能团的基质，即甲基和羟基以及两者的一系列混合物。分别通过X射线光电子能谱和水与十六烷的接触角测量SAMs中羟基的百分比和基质润湿性。SAMs表现出各种基质组成和润湿性，范围从亲水性的、羟基封端的单分子层到疏水性的、甲基封端的单分子层。在层流室中，测量了一种河口细菌在120分钟内附着于这些表面的动力学。通过相差显微镜和数字图像处理对净粘附的初始速率、120分钟后附着的细胞数量、连续测量之间吸附或解吸的附着细胞百分比以及附着细胞的停留时间进行了量化。附着细胞数量最多的情况出现在疏水表面，原因如下：（i）粘附的初始速率以及120分钟后附着的细胞平均数随SAM的甲基含量以及水的接触角增加而增加；（ii）连续测量之间（约2分钟）解吸的细胞百分比随基质疏水性增加而降低。对于所有表面，在120分钟暴露期内解吸的细胞中有60%至80%的停留时间少于10分钟，这表明在所有测试表面上牢固粘附的建立都很快。
