Characterization of potassium-solubilizing fungi, Mortierella spp., isolated from a poplar plantation rhizosphere soil

• Published in: Archives of microbiology 2024-04, Vol.206 (4), p.157-157, Article 157
• Main Authors: Zhu, Rui, Jin, Long, Sang, Yue, Hu, Shuang, Wang, Bao-Teng, Jin, Feng-Jie
• Format: Article
• Language: English
• Subjects: Biochemistry; Biomedical and Life Sciences; Biotechnology; Carbon sources; Cell Biology; Dissolution; Ecology; Fungi; Hyphal tips; Inorganic salts; Life Sciences; Microbial Ecology; Microbiology; Microorganisms; Mortierella; Organic acids; Original Paper; Phylogeny; Plantations; Polysaccharides; Potassium; Rhizosphere; Rhizosphere microorganisms; Soil microorganisms; Soils; Solubilization; Sporangia; Spores
• ISSN: 0302-8933; 1432-072X
• DOI: 10.1007/s00203-024-03912-w

Potassium-solubilizing microorganisms are capable of secreting acidic chemicals that dissolve and release potassium from soil minerals, thus facilitating potassium uptake by plants. In this study, three potassium-dissolving filamentous fungi were isolated from the rhizosphere soil of a poplar plantation in Jiangsu Province, China. Phylogenetic analyses based on ITS, 18 S, and 28 S showed that these three isolates were most similar to Mortierella . These strains also possessed spherical or ellipsoidal spores, produced sporangia at the hyphal tip, and formed petal-like colonies on PDA media resembling those of Mortierella species. These findings, along with further phenotypic observations, suggest that these isolates were Mortierella species. In addition, the potassium-dissolution experiment showed that strain 2K4 had a relatively high potassium-solubilizing capacity among these isolated fungi. By investigating the influences of different nutrient conditions (carbon source, nitrogen source, and inorganic salt) and initial pH values on the potassium-dissolving ability, the optimal potassium-solubilization conditions of the isolate were determined. When potassium feldspar powder was used as an insoluble potassium source, isolate 2K4 exhibited a significantly better polysaccharide aggregation ability on the formed mycelium–potassium feldspar complex. The composition and content of organic acids secreted by strain 2K4 were further detected, and the potassium-dissolution mechanism of the Mortierella species and its growth promotion effect were discussed, using maize as an example.