马利亚霉菌(Mariannaeasp.) HJ合成金属硒化物及机理研究

背景] 金属硒化物因其优异的光电和催化特性，近年来在半导体、电化学及抗癌等领域成为了研究热点。相较于传统的化学还原法，生物合成金属硒化物具有环境友好、耗能较低等优势。然而，目前有关生物合成金属硒化合物的微生物资源较少且相关合成机理尚不明晰。目的] 利用马利亚霉菌（Mariannaea sp.） HJ合成了3种金属硒化物并对其合成机理进行了初步探索。方法] 利用X射线衍射（X-Ray Diffraction，XRD）和傅里叶转换红外线光谱（Fourier Transform Infrared Spectroscopy，FTIR）对菌株HJ合成的金属硒化物进行了初步的表征，考察了纳米材料合成过程中总巯基含量、总抗氧化性能及自由基含量变化，并且验证了转运蛋白DMT1在金属硒化物合成中所起的关键性作用。结果] XRD结果表明菌株HJ能够在Bi³⁺、Pb²⁺、Co²⁺与SeO₃^2-作用下分别合成Bi₄Se₃、PbSe和CoSe₂纳米颗粒，其合成的最优pH条件分别为6.0、7.0、8.0。FTIR结果表明，合成的金属硒化物表面含有氨基、羧基、羟基等官能团。3种金属硒化物的合成反应体系与空白对照组相比，总巯基含量明显下降，而总抗氧化性能却有所提高，这表明巯基等酶促体系或氨基酸金属蛋白类的非酶促体系可能参与了SeO₃^2-的还原过程。苄基异硫脲盐酸盐屏蔽实验表明，转运蛋白DMT1在SeO₃^2-转运和金属硒化物分泌过程中起到关键作用。此外，Bi³⁺、Pb²⁺和Co²⁺的加入使得菌株HJ产生氧化应激反应，在胞外分泌了大量的过氧化氢、羟基自由基和超氧自由基，而上述自由基可通过诱导热激效应的方式增强金属离子或纳米颗粒的转运过程。结论] 利用马利亚霉菌（Mariannaeasp.） HJ合成了Bi₄Se₃、PbSe和CoSe₂纳米颗粒，为研究金属硒化物的生物合成及机理提供了一定的理论参考。

Characterization and mechanism of metal selenides synthesized by Mariannaea sp. HJ

Background] Metal selenides have attracted increasing attention in semiconductor, electrochemistry and anticancer fields due to its excellent photoelectric and catalytic properties. Compared with the traditional chemical methods, biosynthesis of metal selenides is environmentally friendly and lower energy. However, few studies on the biosynthesis of metal selenides were reported, and its relevant mechanisms were still unclear. Objective] We chose Mariannaea sp. HJ to synthesize three kinds of metal selenides and proposed the possible mechanisms. Methods] X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to initially characterize the metal selenides synthesized by strain HJ. The changes in total sulfhydryl content, total antioxidant capacity and free radical content were investigated during the synthesis process. Besides, the function of transporter DMT1 was also verified in the synthesis of metal selenides. Results] XRD results showed that Bi₄Se₃, PbSe and CoSe₂ nanoparticles could be separately biosynthesized by strain HJ under the action of Bi³⁺, Pb²⁺, Co²⁺ and SeO₃^2-, and the optimal pH conditions for their synthesis were 6.0, 7.0, and 8.0, respectively. FTIR analysis illustrated that these nanoparticles were covered with certain functional groups such as amino, carboxyl and hydroxyl groups. Compared to the control group, it was also found that the total sulfhydryl concentration was significantly reduced during the synthesis process, while the total antioxidant performance was increased. It was indicated that the sulfhydryl system or the non-enzymatic system of amino acid metalloproteins could be involved in the reduction of SeO₃^2-. The benzylisothioureas shielding experiment showed that metal transporter DMT1 played a key role in SeO₃^2- transportation and metal selenides secretion. Besides, oxidative stress was produced after the addition of Bi³⁺, Pb²⁺and Co²⁺, which caused strain HJ to secrete more hydrogen peroxide, hydroxyl free radicals and superoxide free radicals outside the cells. The transportation process of metal ions or nanoparticles could be enhanced by above free radicals through inducing heat shock effects. Conclusion] Mariannaea sp. HJ could greenly synthesize Bi₄Se₃, PbSe and CoSe₂ nanoparticles. This study would provide useful information for biosynthesis and mechanism of metal selenides.