Biotechnology Bulletin ›› 2023, Vol. 39 ›› Issue (5): 286-296.doi: 10.13560/j.cnki.biotech.bull.1985.2022-1031

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Identification of a Uranium-resistant Strain and Its Growth-promoting Properties

LUO Yi1(), ZHANG Li-juan2,3, HUANG Wei2, WANG Ning2, Wuerlika MAITIHASEM4, SHI Chong1(), WANG Wei2()   

  1. 1. College of Resources and Environment, Xinjiang Agricultural University, Urumqi 830052
    2. Institute of Applied Microbiology, Xinjiang Academy of Agricultural Sciences, Xinjiang Key Laboratory of Special Environmental Microbiology, Urumqi 830091
    3. College of Grassland Science, Xinjiang Agricultural University, Urumqi 830052
    4. College of Science and Technology, Xinjiang Agricultural University, Urumqi 830052
  • Received:2022-08-23 Online:2023-05-26 Published:2023-06-08
  • Contact: SHI Chong, WANG Wei E-mail:651335178@qq.com;shichong98@163.com;mypony926@163.com

Abstract:

To provide excellent strain resources for the microbial-phytoremediation technologies of uranium-contaminated soil, and to solve the problem of uranium pollution treatment in the decommissioned mining area, the uranium-resistant and plant growth-promoting bacteria were isolated from the soil collected from the decommissioned uranium mine. Gradient dilution of contaminated soil in a decommissioned uranium mine was conducted, and a uranium-resistant strain B2 was isolated on uranium-containing nutrient agar. Then the preliminary identification of strain B2 was carried out by morphological observation, physiological, and biochemical experiments, and 16S rDNA sequence analysis. To analyze the uranium tolerance and uranium adsorption capacity of strain B2, the growth curves and uranium content of the mediums under uranium stress were measured by spectrophotometric method. The abilities of nitrogen fixation, phosphate solubilization, cellulase production, and siderophore were determined by plate methods. The production of 3-indole acetic acid(IAA)was determined by Salkowski colorimetric method, and the growth-promoting ability was verified by seed germination and potting experiment. The morphological observations, physiological and biochemical characteristics, and evolutionary analysis based on 16S rDNA sequences showed that strain B2 was a Microvirga makkahensis sp., and its growth curves conformed to the S-shaped growth curve model at a uranium concentration of 0-400 mg/L. Its growth was inhibited when the uranium concentration reached 600 mg/L. It showed no adsorption effect on uranium. Strain B2 had the probiotic properties of nitrogen fixation, phosphate solubilization, cellulase production, siderophore, and IAA production. IAA production reached 24.39 μg/mL after 48 h incubation. Strain B2 significantly improved the seed germination rate of Brassica chinensis L. and promoted the growth and development of seedlings, significantly increased the biomass of B. chinensis L. Strain B2 is a uranium-resistant M. makkahensis sp. with IAA production and other growth-promoting abilities, which can effectively promote the germination of B. chinensis L. seeds and seedling growth, and can be a candidate strain for the in plant-microbe remediation of uranium-contaminated soil.

Key words: uranium-resistant, plant growth-promoting, Microvirga makkahensis, 3-indole acetic acid(IAA), seed germination, seedling growth, biomass, Brassica chinensis L.