Rosenberg M, Buivids I A, Ellen R P
Faculty of Dentistry, University of Toronto, Ontario, Canada.
J Bacteriol. 1991 Apr;173(8):2581-9. doi: 10.1128/jb.173.8.2581-2589.1991.
Interbacterial adhesion (coadhesion) is considered a major determinant of dental plaque ecology. In this report, we studied several aspects of the adhesion of Porphyromonas (Bacteroides) gingivalis to hexadecane in order to use the liquid hydrocarbon as a convenient substratum for coadhesion assays. Washed suspensions of hydrophobic P. gingivalis 2561 cells were vortexed with hexadecane to yield highly stable cell-coated droplets. Kinetics of coadhesion between Actinomyces viscosus cells and P. gingivalis-coated hexadecane droplets (PCHD) was subsequently studied. Aliquots of PCHD were added to A. viscosus suspensions, and the mixtures were gently rotated. Avid adhesion of A. viscosus cells to the immobilized P. gingivalis layer could be readily measured by the decrease in turbidity in the aqueous phase, following phase separation. Despite the ability of A. viscosus cells to adsorb to hexadecane following vigorous mixing, gentle mixing did not appreciably promote adhesion to bare hexadecane. Moreover, extensive microscopic examinations revealed that A. viscosus cells adhered exclusively to the bound P. gingivalis cells rather than to exposed areas of hexadecane. Coadhesion of A. viscosus to the PCHD appeared to follow first-order kinetics, attaining 80% levels within 30 min. Electron micrographs revealed A. viscosus cells adhering to the P. gingivalis cell layer adsorbed at the hexadecane-water interface. Interestingly, P. gingivalis cells did not appear to penetrate the hexadecane. A viscosus mutants lacking type 1 or type 2 fimbriae or both were still able to bind to the PCHD. No obvious correlation was observed between relative hydrophobicity of A. viscosus strains and their binding to PCHD. However, defatted bovine serum albumin, an inhibitor of hydrophobic interactions, was the most potent inhibitor among those tested. The data suggest that this approach provides a simple, quantitative technique for studying kinetics of bacterial coadhesion which is amenable to both light and electron microscopic observation.
细菌间黏附（共黏附）被认为是牙菌斑生态的一个主要决定因素。在本报告中，我们研究了牙龈卟啉单胞菌（拟杆菌属）与十六烷黏附的几个方面，以便将液态烃用作共黏附测定的便捷底物。将疏水性牙龈卟啉单胞菌2561细胞的洗涤悬浮液与十六烷涡旋混合，以产生高度稳定的细胞包被液滴。随后研究了黏性放线菌细胞与牙龈卟啉单胞菌包被的十六烷液滴（PCHD）之间的共黏附动力学。将等分的PCHD加入到黏性放线菌悬浮液中，混合物轻轻旋转。黏性放线菌细胞对固定化牙龈卟啉单胞菌层的强烈黏附可通过相分离后水相中浊度的降低轻易测定。尽管黏性放线菌细胞在剧烈混合后能够吸附到十六烷上，但轻轻混合并没有明显促进其对裸露十六烷的黏附。此外，广泛的显微镜检查表明，黏性放线菌细胞仅黏附于结合的牙龈卟啉单胞菌细胞，而不是十六烷的暴露区域。黏性放线菌与PCHD的共黏附似乎遵循一级动力学，在30分钟内达到80%的水平。电子显微镜照片显示，黏性放线菌细胞黏附于吸附在十六烷 - 水界面的牙龈卟啉单胞菌细胞层。有趣的是，牙龈卟啉单胞菌细胞似乎没有穿透十六烷。缺乏1型或2型菌毛或两者的黏性放线菌突变体仍然能够与PCHD结合。在黏性放线菌菌株的相对疏水性与其与PCHD的结合之间未观察到明显的相关性。然而，脱脂牛血清白蛋白，一种疏水相互作用的抑制剂，是所测试抑制剂中最有效的。数据表明，这种方法为研究细菌共黏附动力学提供了一种简单、定量的技术，适用于光学和电子显微镜观察。
