Screening of Selenium-resistant Strains in Soil and Evaluation of Selenium Activation Ability

  Objectives  Selenium (Se)-resistant strains were isolated from the slag, silt and farmland soil of the Xintang Township ,Shuanghe Town, Enshi, Hubei Province. And the ability of the selected strains to activate soil Se was evaluated.

  Methods  Using the dilution coating plate method and the plate dashing method, the strains with higher sodium Se resistance were isolated and screened. Classification and determination were carried out by morphological characteristics and molecular biology methods. The isolated Se-tolerant strains were then inoculated in acid Se-rich red soil for culture, and the ability of the two strains to activate soil Se was evaluated by measuring the Se content in the soil after the culture.

  Results  Two Se-resistant strains of bacteria B-1 and fungal B-2 were screened. Bacteria B-1 were identified as Stenotrophomonas maltophilia, which has a concentration of 17000 μg·mL⁻¹. It could grow normally when the temperatures was 20-35 ℃, the pH was 5-9, and the NaCl mass fraction was 0%-3%. Fungus B-2 was identified as Aspergillus sydowii, which has a concentration of 6000 μg mL⁻¹. It could grow normally when the temperatures was 25-30 ℃, the pH was 4-7, and the NaCl mass fraction was 2%-5%. After the addition of two Se-resistant strains for culture, and the content of soluble Se and exchangeable Se in the soil were significantly increased.

  Conclusions  The two strains selected showed high Se tolerance and had good activity of Se in acid Se-rich soil. The availability of Se-resistant strain resources could provide biological species resources and technical means for the development and utilization of Se-rich soil resources. It is also of great significance in the research and development of Se-rich microbial fertilizers, the production of Se-rich agricultural products, and the environmental restoration of Se-contaminated soils.