title: A study of organic acid production in contrasts between two phosphate solubilizing fungi: Penicillium oxalicum and Aspergillus niger.
abstract: Phosphate solubilizing fungi (PSF) have huge potentials in enhancing release of phosphorus from fertilizer. Two PSF (NJDL-03 and NJDL-12) were isolated and identified as Penicillium oxalicum and Aspergillus niger respectively in this study. The quantification and identification of organic acids were performed by HPLC. Total concentrations of organic acids secreted by NJDL-03 and NJDL-12 are ~4000 and ~10,000 mg/L with pH values of 3.6 and 2.4 respectively after five-days culture. Oxalic acid dominates acidity in the medium due to its high concentration and high acidity constant. The two fungi were also cultured for five days with the initial pH values of the medium varied from 6.5 to 1.5. The biomass reached the maximum when the initial pH values are 4.5 for NJDL-03 and 2.5 for NJDL-12. The organic acids for NJDL-12 reach the maximum at the initial pH = 5.5. However, the acids by NJDL-03 continue to decrease and proliferation of the fungus terminates at pH = 2.5. The citric acid production increases significantly for NJDL-12 at acidic environment, whereas formic and oxalic acids decrease sharply for both two fungi. This study shows that NJDL-12 has higher ability in acid production and has stronger adaptability to acidic environment than NJDL-03.
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors.forename: Tongshuo
authors.initials: T
authors.lastname: Bai
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors.forename: Letian
authors.initials: L
authors.lastname: Dai
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors.forename: Fuwei
authors.initials: F
authors.lastname: Wang
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors.forename: Jinjin
authors.initials: J
authors.lastname: Tao
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors.forename: Shiting
authors.initials: S
authors.lastname: Meng
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors.forename: Yunxiao
authors.initials: Y
authors.lastname: Hu
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors.forename: Shimei
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.|Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA.
authors.forename: Shuijin
authors.initials: S
authors.lastname: Hu
mesh_terms: D001234:Aspergillus niger / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D002264:Carboxylic Acids / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010407:Penicillium / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*
chemical_list: D002264:Carboxylic Acids; D003470:Culture Media; D010710:Phosphates