Department of Microbiology, MES Abasaheb Garware College Affiliated to Savitribai Phule Pune University, Pune, Maharashtra, India.
Annasaheb Kulkarni Department of Biodiversity MES Abasaheb Garware College Affiliated to Savitribai Phule Pune University, Pune, Maharashtra, India.
Curr Microbiol. 2023 Jan 30;80(3):86. doi: 10.1007/s00284-023-03186-3.
Several pathogenic bacteria communicate using N-acyl homoserine lactone (AHL) as a quorum sensing (QS) molecule. The process of interfering with the QS system is known as quorum quenching (QQ), it is an effective tool to control QS-dependent virulence in pathogens. In the present study, rhizosphere bacterial isolates were screened for their ability to produce AHL lactonase enzyme as QQ molecules, which hydrolyses AHL signalling molecules and consequently blocks the QS system. Potent N-hexanoyl-l-homoserine lactone (C6HSL) hydrolytic QQ activity was detected in rhizosphere isolates namely Bacillus cereus G and Priestia aryabhattai J1D. The cell-free supernatant of the bacterial isolates indicated a reduction in biofilm formation in the human pathogens Vibrio cholerae, Pseudomonas aeruginosa, and Staphylococcus aureus without inhibiting cells, signifying their biocontrol property. Furthermore, liquid chromatography high resolution mass spectrometry analysis confirmed C6HSL hydrolytic activity by AHL lactonase produced by these rhizosphere isolates. Also, the aiiA homologous gene from the bacterial isolates showed similarity with the aiiA lactonase gene from Bacillus species, which was further confirmed by homology modelling. In silico structure analysis by comparing with the structure of Bacillus revealed the similarity in the active site, indicating the same degradation pattern. Based on available reported data, the present study indicates the first report of the presence of the aiiA lactonase gene in P. aryabhattai.
几种病原菌利用 N-酰基高丝氨酸内酯（AHL）作为群体感应（QS）分子进行交流。干扰 QS 系统的过程称为群体感应淬灭（QQ），它是控制病原菌中 QS 依赖性毒力的有效工具。在本研究中，筛选了根际细菌分离物，以确定其产生 AHL 内酯酶作为 QQ 分子的能力，该酶可水解 AHL 信号分子，从而阻断 QS 系统。在根际分离物中检测到了强大的 N-己酰基-L-高丝氨酸内酯（C6HSL）水解 QQ 活性，即芽孢杆菌 G 和 Priestia aryabhattai J1D。细菌分离物的无细胞上清液表明，在人类病原体霍乱弧菌、铜绿假单胞菌和金黄色葡萄球菌中，生物膜形成减少，而不会抑制细胞，这表明它们具有生物防治特性。此外，高效液相色谱高分辨质谱分析证实了这些根际分离物产生的 AHL 内酯酶对 C6HSL 的水解活性。此外，来自细菌分离物的 aiiA 同源基因与芽孢杆菌的 aiiA 内酯酶基因具有相似性，这进一步通过同源建模得到了证实。通过与芽孢杆菌的结构进行比较的计算机模拟结构分析表明，活性位点具有相似性，表明具有相同的降解模式。根据现有报道的数据，本研究表明首次在 P. aryabhattai 中发现了 aiiA 内酯酶基因的存在。
