Staphylococcus aureus, a Gram-positive bacterium has been implicated in a plethora of human infections by virtue of its biofilm-forming ability. Inhibition in microbial biofilm formation has been found to be a promising approach towards compromising microbial pathogenesis. In this regard, various natural and synthetic molecules have been explored to attenuate microbial biofilm. In this study, the role of an amino acid, L-tryptophan was examined against the biofilm-forming ability of S. aureus. The compound did not execute any antimicrobial characteristics, instead, showed strong antibiofilm activity with the highest biofilm inhibition at a concentration of 50 µg/mL. Towards understanding the underlying mechanism of the same, efforts were given to examine whether tryptophan could inhibit biofilm formation by interfering with the quorum-sensing property of S. aureus. A molecular docking analysis revealed an efficient binding between the quorum-sensing protein, AgrA, and tryptophan. Moreover, the expression of the quorum-sensing gene (agrA) got significantly reduced under the influence of the test compound. These results indicated that tryptophan could interfere with the quorum-sensing property of the organism thereby inhibiting its biofilm formation. Further study revealed that tryptophan could also reduce the cell surface hydrophobicity of S. aureus by downregulating the expression of dltA. Moreover, the tested concentrations of tryptophan did not show any significant cytotoxicity. Hence, tryptophan could be recommended as a potential antibiofilm agent to manage the biofilm-associated infections caused by S. aureus.

金黄色葡萄球菌是一种革兰氏阳性细菌，因其生物膜形成能力而与多种人类感染有关。已发现抑制微生物生物膜形成是损害微生物发病机制的一种有前途的方法。在这方面，已经探索了各种天然和合成分子来减弱微生物生物膜。在这项研究中，检查了氨基酸 L-色氨酸对金黄色葡萄球菌生物膜形成能力的作用。该化合物没有任何抗菌特性，而是表现出很强的抗生物膜活性，在浓度为 50 µg/mL 时具有最高的生物膜抑制作用。为了了解其潜在机制，我们努力研究色氨酸是否可以通过干扰金黄色葡萄球菌的群体感应特性来抑制生物膜形成。分子对接分析揭示了群体感应蛋白 AgrA 和色氨酸之间的有效结合。此外，群体感应基因（ agrA ）的表达在测试化合物的影响下显着降低。这些结果表明色氨酸可以干扰生物体的群体感应特性，从而抑制其生物膜的形成。进一步研究发现色氨酸还可以通过下调dltA的表达来降低金黄色葡萄球菌细胞表面的疏水性。此外，色氨酸的测试浓度没有显示出任何显着的细胞毒性。因此，色氨酸可被推荐作为潜在的抗生物膜剂来控制由金黄色葡萄球菌引起的生物膜相关感染。