Department of Microbiology and Immunology, Faculty of Pharmacy, Tanta University, Tanta, Egypt.
BMC Microbiol. 2024 Nov 27;24(1):502. doi: 10.1186/s12866-024-03542-8.
Pathogenic Escherichia coli is a known harmful microorganism that takes advantage of favorable conditions to cause various infections in healthcare settings, such as bloodstream infections related to catheters, as well as infections in the urinary and respiratory tracts. E. coli utilizes biofilm development as a means to enhance its virulence and pathogenicity. This work aims to investigate the antibiofilm activity of α-amylase enzyme against uropathogenic E. coli (UPEC) and its effect on biofilm-regulatory genes.
In this study, we evaluated the antibiofilm activity of α-amylase enzyme by spectrophotometric microtiter plate analysis and confocal laser scanning microscopy. Also, the antibacterial activity of the test enzyme was evaluated by measuring the MIC and MBC levels against UPEC. The quorum-quenching activity of α-amylase enzyme was assessed using a qRT-PCR to evaluate the impact on biofilm-regulatory genes.
Based on our results, purified α-amylase showed MIC and MBC levels ranged between 128 and 512 µg /ml against UPEC isolates using broth microdilution assay. Crystal violet assay revealed MBIC of 128 µg/ml and MBEC of 256 µg/ml for the purified α-amylase. When the biofilm was analyzed by confocal laser scanning microscope, our results showed inhibition of biofilm thickness (56%) and live/dead cell percentages (43/55%). Furthermore, analysis of the effect on the expression of biofilm-encoding genes showed downregulation of both fimH and papC genes by 57 and 25%, respectively, upon treatment of UPEC with ½ of the MIC (64 µg/ml).
The results demonstrate that our purified α-amylase from B. cereus exhibits promising antibiofilm activities against UPEC at both phenotypic as well as genotypic levels. These findings suggest that this enzyme may serve as a natural effective tool for removing bacterial biofilms, potentially offering new therapeutic avenues for treating infections caused by UPEC.
致病性大肠杆菌是一种已知的有害微生物，它会利用有利条件在医疗环境中引起各种感染，如与导管相关的血流感染以及尿路和呼吸道感染。大肠杆菌利用生物膜的发展来增强其毒力和致病性。本研究旨在探讨α-淀粉酶对尿路致病性大肠杆菌（UPEC）的抗生物膜活性及其对生物膜调控基因的影响。
在这项研究中，我们通过分光光度微板分析和共焦激光扫描显微镜评估了α-淀粉酶的抗生物膜活性。此外，还通过测定 MIC 和 MBC 水平来评估测试酶对 UPEC 的抗菌活性。通过 qRT-PCR 评估α-淀粉酶的群体感应淬灭活性，以评估其对生物膜调控基因的影响。
根据我们的结果，使用肉汤微量稀释法，纯化的α-淀粉酶对 UPEC 分离株的 MIC 和 MBC 水平在 128 至 512μg/ml 之间。结晶紫测定法显示纯化的α-淀粉酶的 MBIC 为 128μg/ml，MBEC 为 256μg/ml。当通过共焦激光扫描显微镜分析生物膜时，我们的结果显示抑制生物膜厚度（56%）和活/死细胞百分比（43/55%）。此外，分析对生物膜编码基因表达的影响表明，在用 MIC 的一半（64μg/ml）处理 UPEC 时，fimH 和 papC 基因的表达分别下调了 57%和 25%。
结果表明，我们从蜡样芽胞杆菌中纯化的α-淀粉酶在表型和基因型水平上均对 UPEC 表现出有希望的抗生物膜活性。这些发现表明，该酶可能是一种天然有效的去除细菌生物膜的工具，为治疗由 UPEC 引起的感染提供了新的治疗途径。
