Tormo M Ángeles, Úbeda Carles, Martí Miguel, Maiques Elisa, Cucarella Carme, Valle Jaione, Foster Timothy J, Lasa Íñigo, Penadés José R
Departamento de Química, Bioquímica y Biología Molecular, Universidad Cardenal Herrera-CEU, 46113 Moncada, Valencia, Spain.
Centro de Investigación y Tecnología Animal, Instituto Valenciano de Investigaciones Agrarias (CITA-IVIA), Apdo. 187, 12.400 Segorbe, Castellón, Spain.
Microbiology (Reading). 2007 Jun;153(Pt 6):1702-1710. doi: 10.1099/mic.0.2006/005744-0.
A process of phase variation is described that affects the expression of Bap (biofilm-associated protein) in Staphylococcus aureus. Upon subculture of the Bap-positive S. aureus strain V329 on Congo red agar, spontaneous smooth biofilm-negative colonies appeared at a low frequency (5 x 10(-4)). Northern blot analysis of these variants with a bap-specific gene probe showed that transcription of the bap gene did not occur. However, DNA typing, Southern blot hybridization and DNA sequencing did not show any differences between the parent V329 strain and the biofilm-negative variants. The biofilm-negative phenotype reverted to wild-type at a similar frequency upon subculture of Bap-negative variants in liquid media. Experimental infection of ovine mammary glands with Bap-negative variants showed that phase variation occurred in vivo, because Bap-expressing, biofilm-positive revertants were isolated from infected mammary glands. The absence of Bap correlated with increased adherence to fibrinogen and fibronectin. It is possible that S. aureus can detach from a biofilm by switching to a Bap-negative state.
描述了一种相变过程，该过程影响金黄色葡萄球菌中生物膜相关蛋白（Bap）的表达。在刚果红琼脂上对Bap阳性的金黄色葡萄球菌菌株V329进行传代培养时，自发出现光滑的生物膜阴性菌落，频率较低（5×10⁻⁴）。用bap特异性基因探针对这些变体进行Northern印迹分析表明，bap基因不发生转录。然而，DNA分型、Southern印迹杂交和DNA测序未显示亲本V329菌株与生物膜阴性变体之间存在任何差异。在液体培养基中对Bap阴性变体进行传代培养时，生物膜阴性表型以相似频率恢复为野生型。用Bap阴性变体对绵羊乳腺进行实验性感染表明，相变在体内发生，因为从感染的乳腺中分离出了表达Bap的生物膜阳性回复株。Bap的缺失与对纤维蛋白原和纤连蛋白的粘附增加相关。金黄色葡萄球菌有可能通过转变为Bap阴性状态从生物膜上脱离。
