Valle Jaione, Da Re Sandra, Schmid Solveig, Skurnik David, D'Ari Richard, Ghigo Jean-Marc
Unité de Génétique des Biofilms, Institut Pasteur (CNRS URA 2172), 25 rue du Dr. Roux, 75724 Paris Cedex 15, France.
J Bacteriol. 2008 Jan;190(1):264-74. doi: 10.1128/JB.01405-07. Epub 2007 Nov 2.
Biofilms are structured communities characterized by distinctive gene expression patterns and profound physiological changes compared to those of planktonic cultures. Here, we show that many gram-negative bacterial biofilms secrete high levels of a small-molecular-weight compound, which inhibits the growth of only Escherichia coli K-12 and a rare few other natural isolates. We demonstrate both genetically and biochemically that this molecule is the amino acid valine, and we provide evidence that valine production within biofilms results from metabolic changes occurring within high-density biofilm communities when carbon sources are not limiting. This finding identifies a natural environment in which bacteria can encounter high amounts of valine, and we propose that in-biofilm valine secretion may be the long-sought reason for widespread but unexplained valine resistance found in most enterobacteria. Our results experimentally validate the postulated production of metabolites that is characteristic of the conditions associated with some biofilm environments. The identification of such molecules may lead to new approaches for biofilm monitoring and control.
生物膜是一种结构化群落，与浮游培养物相比，具有独特的基因表达模式和深刻的生理变化。在此，我们表明许多革兰氏阴性菌生物膜会分泌高水平的小分子化合物，该化合物仅抑制大肠杆菌K-12和其他极少数天然分离株的生长。我们通过遗传学和生物化学方法证明该分子是氨基酸缬氨酸，并且我们提供证据表明生物膜内缬氨酸的产生是由于在碳源不限制的情况下高密度生物膜群落中发生的代谢变化所致。这一发现确定了一个细菌会遇到大量缬氨酸的自然环境，并且我们提出生物膜内缬氨酸的分泌可能是大多数肠杆菌中广泛存在但无法解释的缬氨酸抗性的长期寻找的原因。我们的结果通过实验验证了与某些生物膜环境相关条件下假定的代谢产物的产生。此类分子的鉴定可能会带来生物膜监测和控制的新方法。
