Santos Catarina Angeli, Lima Emília Maria França, Miguel Cristina Maira Turim Santos, Pinto Uelinton Manoel
Food Research Center, Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo (USP).
Food Research Center, Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo (USP);
J Vis Exp. 2025 Aug 8(222). doi: 10.3791/68507.
Bacteria communicate through a system known as quorum sensing (QS), which allows them to coordinate their behavior in response to changes in cell density. This process involves the production, secretion, and detection of small extracellular signaling molecules, usually called autoinducers (AI). QS regulates a wide range of genes and functions, including biofilm formation and dispersal, swarming motility, production of virulence factors, antibiotic resistance, and bioluminescence, among others. QS inhibition has become a promising antivirulence strategy against antibiotic-resistant bacteria as it exerts a lower selective pressure compared to traditional antibiotics. In the bacterium Chromobacterium violaceum ATCC 12472, the QS proteins CviI/CviR, which are homologous to the LuxI/LuxR-type QS proteins of Aliivibrio fisheri, control many genes, including those responsible for producing the purple pigment violacein. C. violaceum has been widely used as a biosensor strain in QS inhibition studies, particularly the inhibition of violacein production. Many compounds have the potential to inhibit QS by binding to QS proteins, either LuxI or LuxR homologues, disrupting QS circuits. This protocol describes the method for quantifying violacein produced by C. violaceum ATCC 12472 and its inhibition by bioactive compounds at concentrations that do not affect bacterial growth. The assay described here demonstrates a significant reduction in violacein production by the tested compounds. This study highlights the potential for using this protocol to screen promising candidates in QS inhibition research.
细菌通过一种称为群体感应（QS）的系统进行通讯，该系统使它们能够根据细胞密度的变化来协调其行为。这个过程涉及小细胞外信号分子的产生、分泌和检测，这些分子通常被称为自诱导物（AI）。群体感应调节广泛的基因和功能，包括生物膜的形成与分散、群体游动性、毒力因子的产生、抗生素抗性和生物发光等。与传统抗生素相比，群体感应抑制已成为一种有前景的抗耐药菌抗毒力策略，因为它施加的选择压力较低。在紫色色杆菌ATCC 12472中，与费氏弧菌的LuxI/LuxR型群体感应蛋白同源的群体感应蛋白CviI/CviR控制许多基因，包括那些负责产生紫色色素紫菌素的基因。紫色色杆菌已被广泛用作群体感应抑制研究中的生物传感器菌株，特别是在抑制紫菌素产生方面。许多化合物有可能通过与群体感应蛋白（LuxI或LuxR同源物）结合来抑制群体感应，从而破坏群体感应回路。本方案描述了定量紫色色杆菌ATCC 12472产生的紫菌素及其被生物活性化合物抑制的方法，这些化合物的浓度不会影响细菌生长。此处描述的测定表明，受试化合物使紫菌素产量显著降低。这项研究突出了使用该方案在群体感应抑制研究中筛选有前景候选物的潜力。
