title: Inhibition of Aspergillus niger phosphate solubilization by fluoride released from rock phosphate.
abstract: The simultaneous release of various chemical elements with inhibitory potential for phosphate solubilization from rock phosphate (RP) was studied in this work. Al, B, Ba, Ca, F, Fe, Mn, Mo, Na, Ni, Pb, Rb, Si, Sr, V, Zn, and Zr were released concomitantly with P during the solubilization of Araxá RP (Brazil), but only F showed inhibitory effects on the process at the concentrations detected in the growth medium. Besides P solubilization, fluoride decreased fungal growth, citric acid production, and medium acidification by Aspergillus niger. At the maximum concentration found during Araxá RP solubilization (22.9 mg F(-) per liter), fluoride decreased P solubilization by 55%. These findings show that fluoride negatively affects RP solubilization by A. niger through its inhibitory action on the fungal metabolism. Given that fluoride is a common component of RPs, the data presented here suggest that most of the microbial RP solubilization systems studied so far were probably operated under suboptimal conditions.
authors.affiliation: Department of Microbiology, Federal University of Viçosa, Viçosa, Brazil.
authors.forename: Gilberto de Oliveira
authors.initials: Gde O
authors.lastname: Mendes
authors.forename: Nikolay Bojkov
authors.initials: NB
authors.lastname: Vassilev
authors.forename: Victor Hugo Araújo
authors.initials: VH
authors.lastname: Bonduki
authors.forename: Ivo Ribeiro
authors.initials: IR
authors.lastname: da Silva
authors.forename: José Ivo
authors.initials: JI
authors.lastname: Ribeiro
authors.forename: Maurício Dutra
authors.initials: MD
authors.lastname: Costa
mesh_terms: D001234:Aspergillus niger / Q000378:metabolism*; D001938:Brazil; D005459:Fluorides / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D010710:Phosphates / Q000378:metabolism*; D012988:Soil Microbiology; D012995:Solubility; D013054:Spectrophotometry, Atomic
chemical_list: D010710:Phosphates; D005459:Fluorides