耐硒酵母菌生物合成纳米硒的表征及抑菌活性

Characteristics and antimicrobial activities of selenium nanoparticles biosynthesized by selenium-tolerant yeast

摘要:

硒是人体必需的微量元素，对许多由氧化应激引起的疾病具有抗性。纳米硒(selenium nanoparticles, SeNPs)具有低毒和广泛生物活性的优点。为了筛选高效合成SeNPs的菌株，本研究对3株耐硒酵母菌的硒耐受性、SeNPs合成能力、体外抗氧化活性和抑菌活性进行研究，选择出性能最好的菌株M16-28进行表征。结果表明，M16-28菌株能耐受300 mmol/L Na₂SeO₃，其合成SeNPs的能力达1 018.92 μg/mL，是M1菌株合成SeNPs含量的2.86倍。体外抗氧化实验表明，1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl DPPH)自由基清除率为65.7%，羟自由基清除率为57.5%，还原力为0.77。抑菌性试验表明，对革兰氏阳性菌的抑制效果显著高于革兰氏阴性菌，对枸杞茎腐病病原微生物具有显著抑制作用。3株菌合成的SeNPs对镰刀菌属的抑制率均高于90%，对链格孢菌株抑制率较低，M16-28菌株合成的SeNPs抑菌性最高，为(66.53±1.37)%。表征结果表明，SeNPs呈紧密排布，有多糖包裹，带负电荷，尺寸分布在190-390 nm之间，Zeta电位为-7.87 mV。综上所述，M16-28菌株具有较好的合成SeNPs能力，富硒能力和合成SeNPs能力呈正相关，可作为高效合成SeNPs的潜在微生物资源。

Abstract:

Selenium is an essential trace element for the human body, enhancing the body resistance to a variety of diseases induced by oxidative stress. Selenium nanoparticles (SeNPs) possess advantages such as low toxicity and broad biocompatibility. In order to screen for a strain with high efficiency in synthesizing SeNPs, we investigated the selenium tolerance and SeNPs synthesis capacities of three selenium-tolerant yeast strains and the in vitro antioxidant activities and antimicrobial activities of the synthesized SeNPs. Furthermore, we characterized SeNPs synthesized by strain M16-28 with the best performance. The results indicated that strain M16-28 was capable of tolerating 300 mmol/L Na₂SeO₃, with a SeNPs synthesis capacity of 1 018.92 μg/mL, which was 2.86 times that of strain M1. The in vitro antioxidant experiments indicated that the synthesized SeNPs exhibited the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate of 65.7%, the hydroxyl radical scavenging rate of 57.5%, and the reducing power of 0.77. The antimicrobial experiments indicated that the synthesized SeNPs displayed significantly stronger inhibitory effects against Gram-positive bacteria than against Gram-negative bacteria, and they had a significant inhibitory effect on the pathogenic microorganisms causing stem rot of Lycium barbarum. The SeNPs synthesized by the three yeast strains exhibited an inhibition rate higher than 90% against Fusarium spp., and a lower inhibition rate against Alternaria alternata. The SeNPs produced by strain M16-28 exhibited the highest antimicrobial activity, with an inhibition rate of (66.53±1.37)%. Characterization results indicated that SeNPs were closely arranged, encapsulated by polysaccharides, and negatively charged, with a size ranging from 190 nm to 390 nm and the zeta potential of -7.87 mV. In conclusion, strain M16-28 demonstrates ideal performance of synthesizing SeNPs, and the capacity for selenium enrichment is positively correlated with the ability to synthesize SeNPs. This study provides a potential microbial resource for the efficient synthesis of SeNPs.