Novartis Vaccines and Diagnostics, Siena, Italy.
PLoS One. 2010 Nov 5;5(11):e13864. doi: 10.1371/journal.pone.0013864.
Group A Streptococcus (GAS, Streptococcus pyogenes) is a gram-positive human pathogen responsible for a diverse variety of diseases, including pharyngitis, skin infections, invasive necrotizing fasciitis and autoimmune sequelae. We have recently shown that GAS cell adhesion and biofilm formation is associated with the presence of pili on the surface of these bacteria. GAS pilus proteins are encoded in the FCT (Fibronectin-Collagen-T antigen) genomic region, of which nine different variants have been identified so far. In the present study we undertook a global analysis of GAS isolates representing the majority of FCT-variants to investigate the effect of environmental growth conditions on their capacity to form multicellular communities. For FCT-types 2, 3, 5 and 6 and a subset of FCT-4 strains, we observed that acidification resulting from fermentative sugar metabolism leads to an increased ability of the bacteria to form biofilm on abiotic surfaces and microcolonies on epithelial cells. The higher biofilm forming capacity at low environmental pH was directly associated with an enhanced expression of the genes encoding the pilus components and of their transcription regulators. The data indicate that environmental pH affects the expression of most pilus types and thereby the formation of multicellular cell-adhering communities that assist the initial steps of GAS infection.
A 组链球菌（GAS，化脓性链球菌）是一种革兰氏阳性人类病原体，可导致多种疾病，包括咽炎、皮肤感染、侵袭性坏死性筋膜炎和自身免疫后遗症。我们最近表明，GAS 细胞黏附和生物膜形成与这些细菌表面存在菌毛有关。GAS 菌毛蛋白由 FCT（纤维连接蛋白-胶原蛋白-T 抗原）基因组区域编码，迄今为止已鉴定出 9 种不同的变体。在本研究中，我们对代表大多数 FCT 变体的 GAS 分离株进行了全面分析，以研究环境生长条件对其形成多细胞群落能力的影响。对于 FCT 型 2、3、5 和 6 以及 FCT-4 菌株的一个亚组，我们观察到糖发酵代谢导致的酸化会导致细菌在非生物表面和上皮细胞上形成生物膜和微菌落的能力增强。在低环境 pH 值下更高的生物膜形成能力与编码菌毛成分及其转录调节剂的基因的表达增强直接相关。数据表明，环境 pH 值会影响大多数菌毛类型的表达，从而形成有助于 GAS 感染初始步骤的多细胞细胞黏附群落。
