Abstract：
Staphylococcus haemolyticus is a cause of bovine mastitis, leading to inflammation in the mammary gland. This bacterial infection adversely affects animal health, reducing milk quality and yield. Its emergence has been widely reported, representing a significant economic loss for dairy farms. Interestingly, S. haemolyticus exhibits higher levels of antimicrobial resistance than other coagulase-negative Staphylococci. In this study, we synthesized silver/silver chloride nanoparticles (Ag/AgCl-NPs) using Solanum lasiocarpum root extract and evaluated their antibacterial and antibiofilm activities against S. haemolyticus. The formation of the Ag/AgCl-NPs was confirmed using UV-visible spectroscopy, which revealed maximum absorption at 419 nm. X-ray diffraction (XRD) analysis demonstrated the crystalline nature of the Ag/AgCl-NPs, exhibiting a face-centered cubic lattice. Fourier transform infrared (FT-IR) spectroscopy elucidated the functional groups potentially involved in the Ag/AgCl-NPs synthesis. Transmission electron microscopy (TEM) analysis revealed that the average particle size of the Ag/AgCl-NPs was 10 nm. Antimicrobial activity results indicated that the minimum inhibitory concentration (MIC) and maximum bactericidal concentration (MBC) of the Ag/AgCl-NPs treatment were 7.82-15.63 μg/mL towards S. haemolyticus. Morphological changes in bacterial cells treated with the Ag/AgCl-NPs were observed under scanning electron microscopy (SEM). The Ag/AgCl-NPs reduced both the biomass of biofilm formation and preformed biofilm by approximately 20.24-94.66 % and 13.67-88.48 %. Bacterial viability within biofilm formation and preformed biofilm was reduced by approximately 21.56-77.54 % and 18.9-71.48 %, respectively. This study provides evidence of the potential of the synthesized Ag/AgCl-NPs as an antibacterial and antibiofilm agent against S. haemolyticus.
摘要：
溶血葡萄球菌是牛乳腺炎的病因,导致乳腺发炎.这种细菌感染对动物健康产生不利影响，降低牛奶质量和产量。它的出现已经被广泛报道，这对奶牛场来说是巨大的经济损失。有趣的是,溶血链球菌比其他凝固酶阴性葡萄球菌表现出更高水平的抗微生物耐药性。在这项研究中,我们使用龙葵根提取物合成了银/氯化银纳米颗粒（Ag/AgCl-NPs），并评估了它们对溶血链球菌的抗菌和抗生物膜活性。Ag/AgCl-NP的形成使用UV-可见光谱证实,在419nm处显示最大吸收。X射线衍射(XRD)分析表明Ag/AgCl-NP的结晶性质,表现出面心立方晶格。傅里叶变换红外（FT-IR）光谱阐明了Ag/AgCl-NP合成中可能涉及的官能团。透射电子显微镜(TEM)分析显示Ag/AgCl-NP的平均粒径为10nm。抗菌活性结果表明，Ag/AgCl-NP处理对溶血链球菌的最低抑菌浓度（MIC）和最大杀菌浓度（MBC）为7.82-15.63μg/mL。在扫描电子显微镜（SEM）下观察了用Ag/AgCl-NP处理的细菌细胞的形态变化。Ag/AgCl-NP使生物膜形成和预制生物膜的生物量降低了约20.24-94.66％和13.67-88.48％。生物膜形成和预先形成的生物膜内的细菌活力降低了约21.56-77.54％和18.9-71.48％，分别。该研究提供了合成的Ag/AgCl-NP作为抗溶血链球菌的抗菌和抗生物膜剂的潜力的证据。
