| 摘要: |
| 【目的】研究放线菌菌株合成纳米硒（Selenium nanoparticles，SeNPs）的物理化学特性和抑菌促生活性，为菌株在富硒花魔芋生产中的应用提供参考。【方法】利用扫描电镜（SEM）和X射线能谱分析仪（EDS），对从健康花魔芋根际土壤中筛选的放线菌菌株A1的细胞形态及其合成的纳米硒进行观察和元素组成分析；利用X射线衍射仪（XRD）对亚硒酸钠Na2SeO3和菌株A1合成的纳米硒进行晶型结构表征；利用傅里叶红外变换光谱仪（FTIR）对菌株A1合成的纳米硒表面官能团结构进行表征分析。以小麦和玉米种子为材料，将菌株A1的富硒发酵滤液和非富硒发酵滤液分别稀释0，5，50倍，用皿内发芽试验测定纳米硒对种子的促生作用；以花魔芋软腐病原菌菊果胶杆菌（Pectobacterium chrysanthemi）CZS-B6为靶标菌，用滤纸片扩散法和牛津杯法分别测定菌株A1的富硒发酵滤液和非富硒发酵滤液原液的抑菌效果；通过菌落形态、生理生化特性和分子鉴定确定菌株A1的分类地位。【结果】菌株A1介导200 mg/L Na2SeO3合成的红色单质硒为球形纳米颗粒，非晶态，颗粒表面存在Se、C、O、N等有机元素和C-O、N-H、C-H等官能团。经菌株A1富硒发酵滤液原液处理后，小麦和玉米幼苗的主根长及总鲜质量均显著高于无菌水对照（P<0.05）；富硒发酵滤液原液对花魔芋软腐病原菌菊果胶杆菌有较强的拮抗作用，其拮抗圈直径分别为14.6 mm（滤纸片扩散法）和13.1 mm（牛津杯法）。菌株A1的培养特征、生理生化特性及16S rDNA序列分析结果表明，其为波卓链霉菌（Streptomyces bottropensis）。【结论】波卓链霉菌菌株A1介导合成的生物纳米硒具有抑菌和促生活性，在绿色富硒花魔芋种植及软腐病防治等领域具有潜在的应用价值。 |
| 关键词: 放线菌 波卓链霉菌 生物纳米硒 物理化学表征 促生活性 拮抗作用 |
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| 基金项目:国家自然科学基金项目（31901468）；农业部富硒产品开发与质量控制重点实验室项目（Se-2019B02）；中国富硒产业研究院富硒专项研发计划项目（2019QCY-2.2）；安康市科技计划项目(AK2020-CQ01-1)；安康市农业技术推广项目（2017AYHX016） |
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| Physicochemical characteristics of nano-selenium synthesized by Streptomyces bottropensis strain A1 and its anti-bacterial and growth promotion effects |
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HE Fei,CUI Ming,WANG Tian,et al
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| Abstract: |
| 【Objective】This study explored the physicochemical characteristics of nano-selenium synthesized by actinomycete strain A1 and its anti-bacterial and growth promoting activities to provide references for the application of actinomycete A1 in production of Se-enriched konjac (Amorphophallus konjac).【Method】The cell morphology of strain A1 screened from healthy konjac rhizosphere soil and elemental composition of synthesized nano-selenium were observed and analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).The crystal structures of Na2SeO3 and nano-selenium synthesized by strain A1 were characterized by X-ray diffractometer (XRD).Fourier transform infrared spectroscopy (FTIR) was used to analyze the surface functional groups of synthesized nano-selenium.Using wheat and maize seeds as test materials,the growth promoting activity of Se-enriched and non selenium supernatants synthesized by actinomycete strain A1 diluted by 0,5,and 50 times was determined.Using Pectobacterium chrysanthemi strain CZS-B6,the soft rot pathogen of konjac,as the target bacteria,the anti-bacterial activity of Se-enriched and non selenium supernatant synthesized by actinomycete strain A1 was evaluated by the filter paper diffusion and Oxford cup methods, respectively.The strain A1 was also identified based on its morphological characters,physiological and biochemical characteristics,and 16S rDNA sequence.【Result】The red and amorphous spherical selenium nanoparticles (SeNPs) were synthesized by strain A1 with 200 mg/L Na2SeO3.The organic elements (Se,C,O and N) existed in the surface of SeNPs.SeNPs were coated with functional groups,such as C-O,N-H,and C-H.Compared with the control (sterile water),the supernatant of SeNPs significantly improved taproot length and total fresh weight of wheat and maize seedlings (P<0.05).It also exhibited antibacterial activity against Pectobacterium chrysanthemi strain CZS-B6,and the mean diameter of growth inhibition zone was 14.6 mm for filter paper diffusion method and 13.1 mm for the Oxford cup method.The strain A1 was identified as Streptomyces bottropensis based on the cultural,physiological and biochemical characteristics as well as 16S rDNA sequence analysis.【Conclusion】With antibacterial and growth promoting activities,the SeNPs synthesized by Streptomyces bottropensis strain A1 has potential application in the cultivation of green Se-enriched konjac,the prevention and control of soft rot disease,and other fields. |
| Key words: actinomycete Streptomyces bottropensis biological nano-selenium physicochemical characteristics growth-promoting activity antagonism |
