高产铁载体与高效溶磷真菌的筛选及生理特性比较OA

Phosphorus(P)is an essential element for plant growth and development.However,the vast majority of soil P exists in insoluble forms that are largely unavailable for direct plant uptake.Phosphate-solubilizing microorganisms(PSMs)enhance the availability of insoluble soil P through mechanisms such as secreting organic acids and siderophores,thereby promoting plant P absorption and growth.Based on high phosphate-solubilizing capacity and high siderophore production in combination with phylogenetic analysis and physiological characterization,elite fungal strains were screened and obtained from typical phosphorus-limited habitats and their potassium-releasing capacity and biocontrol potential were evaluated.In total,11 fungal isolates possessing both high-efficiency phosphate-solubilizing and high-yield siderophore production capabilities were obtained from saline-alkali soil in Dongying of Shandong and acidic soil of a Chinese fir forest in Shangrao of Jiangxi.After comprehensive screening,seven isolates were selected as elite strains.Strains H2,R13,and R33 exhibited the strongest solubilizing capacities to tricalcium phosphate,iron phosphate,and aluminum phosphate,respectively.The siderophore production of all 7 elite strains reached over 90%of the saturation level within 3 days,and a significant negative correlation was observed between siderophore yield and medium pH.Correlation analysis indicated that tricalcium phosphate dissolution capacity was positively correlated with malic acid and fumaric acid content and siderophore production;iron phosphate dissolution capacity was positively correlated with oxalic acid,acetic acid,citric acid,fumaric acid and succinic acid content and siderophore production;aluminum phosphate dissolution capacity was only positively correlated with tartaric acid content.Siderophore production showed a highly significant positive correlation with citric acid and fumaric acid content,suggesting a synergistic regulatory mechanism with specific organic acids.All 7 strains grew on potassium-releasing medium,but their growth was completely inhibited upon the addition of ferric chloride,indicating that their potassium-releasing capacity was associated with siderophore-related mechanisms.The inhibition rate of the fermentation filtrates of the 7 strains against Fusarium graminearum showed a significant positive correlation with siderophore production.Strain S4,with a siderophore content of 53.16%,achieved an inhibition rate of 87.95%.Based on multi-gene phylogenetic analysis of RPB2 and ITS genes combined with scanning electron microscopy morphological observation,strain H5 was identified as Penicillium adametzii;while R6,R18,H2,H1,and R13 were all identified as Penicillium sp.,clustering closely with P.oxalicum;S4 was identified as Aspergillus sp.,showing a close phylogenetic relationship with A.tubingensis.In summary,the seven elite fungal strains screened in this study demonstrate significant potential in solubilizing various forms of insoluble P,releasing potassium,and inhibiting pathogenic fungi,providing valuable microbial resources for developing novel microbial fertilizers and pesticides.