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Chinese Agricultural Science Bulletin ›› 2026, Vol. 42 ›› Issue (5): 42-49.doi: 10.11924/j.issn.1000-6850.casb2025-0399

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Study on Biological Characteristics and Optimization of Culture Conditions of Two Efficient Phosphate-Solubilizing Bacteria

HU Mingzhu(), ZHANG Junjie, SHI Xuerui, WANG Wei, DAI Jinxia()   

  1. School of Life Sciences, University of Ningxia / Key Laboratory of Western Characteristic Biological Resources Conservation and Utilization, Ministry of Education, Yinchuan 750021
  • Received:2025-05-21 Revised:2025-10-11 Online:2026-03-18 Published:2026-03-18

Abstract:

This study aims to investigate the biological characteristics of phosphate-solubilizing strains B23 and S10, optimize their cultivation conditions, and provide basic data for exploring the phosphate-solubilizing mechanism and preparing phosphate-solubilizing bacterial fertilizers. The Salkowski colorimetric method and the phenol-sulfuric acid method were used to quantitatively determine the strain's IAA production and exopolysaccharide production; single-factor level experiments were adopted to optimize phosphate-solubilizing culture conditions for strains; the colorimetric method was used to determine phosphatase and glucose dehydrogenase in strains; and the effects of the strains on the germination of Avena sativa, Triticum aestivum, and Medicago sativa seeds were investigated through pot experiments. The results indicate that both S10 and B23 have the abilities to produce IAA, dissolve organophosphorus, produce siderophores, produce HCN, and produce exopolysaccharide, with IAA yieds of 18.875 mg/L and 7.603 mg/L respectively; exopolysaccharide yields of 16.290 μg/mL and 16.941 μg/mL respectively,S10 also has the ability to produce NH3. 16S rRNA gene sequence analysis indicates that they belong to the Serratia and Acinetobacter, respectively. The strain exhibits the strongest phosphate-solubilizing effect when the carbon and nitrogen sources are sucrose and urea, with the optimal initial pH values being pH 6.0 and pH 7.0, respectively. Compared with before optimization, the activities of alkaline phosphatase, acid phosphatase, and glucose dehydrogenase in S10 were increased by 33.97%, 47.20%, and 20.94%, respectively; in B23, they were increased by 12.47%, 99.19%, and 54.63%, respectively. Both B23 and S10 can significantly improve the germination vigor, germination rate, and sprout length of Avena sativa, Triticum aestivum, and Medicago sativa. They also have a significant promoting effect on the root length of Avena sativa and Triticum aestivum. The above results indicate that strains S10 and B23 have strong phosphate-solubilizing abilities and multiple plant growth-promoting potentials. They can promote seed germination and may serve as candidate strains for preparing phosphate-solubilizing bio-fertilizers.

Key words: phosphate soluble microorganisms, exopolysaccharides, phosphatase, glucose dehydrogenase, phosphate-solubilizing ability, growth-promoting characteristics, seed germination