Identification and characterization of the rhizosphere phosphate-solubilizing bacterium Pseudomonas frederiksbergensis JW-SD2, and its plant growth-promoting effects on poplar seedlings

摘要

The rhizospheric bacterium JW-SD2 was identified as Pseudomonas frederiksbergensis based on phenotypic features, the Biolog Identification System and 16S rRNA sequence analysis. The phosphate-solubilizing activity, acidification in culture media, growth rate and organic acid secretion of JW-SD2 were investigated during 192?h of cultivation. The phosphate solubilized by JW-SD2 reached 7.75?mM. The decrease in pH and increase of titratable acidity were closely correlated (Pearson’s r?=??0.953 and 0.969, respectively) with the phosphate-solubilizing activity. High concentrations of gluconic, 2-ketogluconic, pyruvic, maleic and malic acids were detected before 96?h of culture when the strain displayed a high level of phosphate-solubilizing activity, indicating that these organic acids were efficient components in phosphate solubilization. However, acetic acid did not affect phosphate solubilization as shown by a remarkable increase at 144?h of culture when the phosphate-solubilizing activity decreased. The phosphate-solubilizing ability of JW-SD2 was significantly (P?