阿维链霉菌合成纳米硒的物理化学表征及其对枸杞病原真菌的抑菌活性

Selenium nanoparticles synthesized by Streptomyces avermitilis: physical and chemical characteristics and inhibitory activity on a pathogen of Lycium barbarum

摘要:

生物合成的纳米硒(selenium nanoparticles,SeNPs)具有独特的物理、化学和生物学特性，备受研究人员关注。为了开发将硒盐还原为SeNPs的菌种，本研究以阿维链霉菌(Streptomyces avermitilis)为研究对象，通过添加一定量的Na₂SeO₃，利用光学显微镜、扫描电镜(scanning electron microscope,SEM)、透射电镜(transmission electron microscope,TEM)、能量色散X射线能谱(energy dispersive spectrometer,EDS)分析、X射线衍射(X-ray diffraction,XRD)分析、傅里叶红外变换光谱(Fourier transform infrared spectroscopy,FTIR)技术对菌体及合成的SeNPs进行物理化学表征分析，同时选用枸杞根腐病主要病原真菌-尖孢镰刀菌(Fusarium oxysporium)对其抗菌活性进行研究。结果表明，阿维链霉菌可将Na₂SeO₃转化成SeNPs，能耐受300 mmol/L的Na₂SeO₃，耐受性较高；阿维链霉菌可在细胞质中合成球形SeNPs，大部分直径在100 nm左右，并以菌丝断裂的方式释放；阿维链霉菌合成的SeNPs颗粒为非晶态，表面以C、Se为主，同时存在O、N等元素，−OH、C=O、C−N、C−H等官能团与SeNPs稳定性和生物活性密切相关；阿维链霉菌所产的SeNPs对F. oxysporium有显著抑制活性，25.0 μmol/mL处理抑菌率可达77.61%，半数效应浓度(median effective concentration,EC₅₀)为0.556μmol/mL。总之，阿维链霉菌可耐受高Na₂SeO₃胁迫，同时还可介导合成SeNPs，合成的SeNPs颗粒具有良好的稳定性和抗菌活性，在SeNPs制备和枸杞根腐病防治方面具有潜在的应用价值。

关键词:阿维链霉菌;纳米硒;物理化学表征;尖孢镰刀菌;抑菌活性

Abstract:

Biosynthesized selenium nanoparticles (SeNPs) have attracted much attention because of their unique physical, chemical, and biological properties. The microbial reduction of selenium salts to SeNPs has great potential, while there is a lack of elite strains. In this study, we explored the reduction of Na₂SeO₃ by Streptomyces avermitilis into SeNPs. The colonies and hyphae of the strain and the synthesized SeNPs were characterized by optical microscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). At the same time, the inhibitory activity of SeNPs on Fusarium oxysporum, the main pathogen causing root rot of Lycium barbarum, was studied. The results showed that S. avermitilis converted Na₂SeO₃ into SeNPs and tolerated 300 mmol/L Na₂SeO₃, demonstrating strong tolerance. S. avermitilis synthesized spherical SeNPs in the cytoplasm, and most of SeNPs had a diameter of about 100 nm and were released by hyphal fracture. The SeNPs synthesized by S. avermitilis were amorphous, and their surfaces were dominated by C and Se, with the existence of O, N and other elements. SeNPs had functional groups such as −OH, C=O, C−N, and C−H, which were closely related to the stability and biological activity of SeNPs. The SeNPs synthesized by S. avermitilis showcased significant inhibitory activity on F. oxysporum, and 25.0 μmol/mL SeNPs showcased the inhibition rate of 77.61% and EC₅₀ of 0.556 μmol/mL. In conclusion, S. avermitilis can tolerate high Na₂SeO₃ stress and mediate the synthesis of SeNPs. The synthesized SeNPs have good stability and strong inhibitory activity, demonstrating the potential application value in the preparation of SeNPs and the control of L. barbarum root rot.

Key words:Streptomyces avermitilis;selenium nanoparticles;physical and chemical characterization;Fusarium oxysporum;inhibitory activity