Biofilm formation by Staphylococcus epidermidis depends on functional RsbU, an activator of the sigB operon:: Differential activation mechanisms due to ethanol and salt stress
Biofilm formation by Staphylococcus epidermidis depends on functional RsbU, an activator of the sigB operon:: Differential activation mechanisms due to ethanol and salt stress
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DOI：
10.1128/jb.183.8.2624-2633.2001
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发表时间：
2001-04-01
影响因子：
3.2
通讯作者：
Mack, D
中科院分区：
文献类型：
--
作者：
Knobloch, JKM;Bartscht, K;Mack, D
表皮葡萄球菌是医疗器械相关感染的常见病原体。其主要致病因素是形成粘附生物膜的能力。多糖细胞间黏附素（PIA）是由icaADBC基因杂散产物合成的，对生物膜的积累至关重要。在本研究中，我们对产生生物膜的表皮葡萄球菌1457的两个等基因、不依赖icaadbc、生物膜阴性突变体M15和M19的Tn917插入灭活的基因位点进行了表征。两个突变体的插入位点相同，且位于与金黄色葡萄球菌和枯草芽孢杆菌的sigB操纵子高度同源的第一个基因rsbU。在胰蛋白酶豆汤中添加氯化钠（TSBNaCl）或乙醇（TSBEtOH），这两种物质都是已知的sigB激活剂，可以增加表皮葡萄球菌1457的生物膜形成和PIA合成。将Tn917插入备选sigma因子(B)的正调节因子rsbU中，导致生物膜阴性表型和几乎无法检测到的PIA产生。有趣的是，在TSBEtOH中，突变体能够再次形成生物膜，其表型与野生型相似。在TSBEtOH中，突变体仍然表现为生物膜阴性表型。我们观察到，突变体和野生型之间的初级附着没有差异。将突变体M15的Tn917插入到独立的产生生物膜的菌株表皮葡萄球菌8400中后，观察到类似的表型变化。在11株表皮葡萄球菌临床菌株中检测到sigB操纵子限制性片段长度多态性，该多态性不依赖于icaADBC位点的存在和生物膜阳性表型，显然，在固定期和盐或乙醇诱导的胁迫下，调控PIA的表达有不同的机制。
Staphylococcus epidermidis is a common pathogen in medical device-associated infections. Its major pathogenetic factor is the ability to form adherent biofilms. The polysaccharide intercellular adhesin (PIA), which is synthesized by the products of the icaADBC gene fluster, is essential for biofilm accumulation. In the present study, we characterized the gene locus inactivated by Tn917 insertions of two isogenic, icaADBC-independent, biofilm-negative mutants, M15 and M19, of the biofilm-producing bacterium S. epidermidis 1457. The insertion site was the same in both of the mutants and wets located in the first gene, rsbU, of an operon highly homologous to the sigB operons of Staphylococcus aureus and Bacillus subtilis. Supplementation of Trypticase soy broth with NaCl (TSBNaCl) or ethanol (TSBEtOH), both of which are known activators of sigB, led to increased biofilm formation and PIA synthesis by S. epidermidis 1457. Insertion of Tn917 into rsbU, a positive regulator of alternative sigma factor sigma (B), led to a biofilm-negative phenotype and almost undetectable PIA production. Interestingly, in TSBEtOH, the mutants were enabled to form a biofilm again with phenotypes similar to those of the wild type. In TSBEtOH, the mutants still displayed a biofilm-negative phenotype. No difference in primary attachment between the mutants and the wild type,vas observed. Similar phenotypic changes were observed after transfer of the Tn917 insertion of mutant M15 to the independent and biofilm-producing strain S. epidermidis 8400. In 11 clinical S. epidermidis strains, a restriction fragment length polymorphism of the sigB operon was detected which was independent of the presence of the icaADBC locus and a biofilm-positive phenotype, Obviously, different mechanisms are operative in the regulation of PIA expression in stationary phase and under stress induced by salt or ethanol.