Phosphorus dissolving capability, glucose dehydrogenase gene expression and activity of two phosphate solubilizing bacteria

Abstract:

[Objective] To identify the function of glucose dehydrogenase (GDH) and gene expression level in the process of solubilizing phosphorus. [Methods] Phosphate solubilizing bacteria (PSB) were isolated and purified by soluble phosphorus circle method, and identified by Vitek 2 system and 16S rRNA sequence. The phosphate solubilization capacity and GDH activity of PSB were determined. GDH genes were cloned by PCR and the relative expression level of both genes under different conditions were determined by real-time quantitative PCR. [Results] Two PSB were identified as Pseudomonas sp. and Enterobacter sp. and the highest phosphorus solubilizing capability was 558 μg/mL for the former and 478 μg/mL for the latter. GDH genes of the two bacteria were cloned and the fragments were 2007 bp and 2066 bp. Different GDH activity and GDH gene expression were cultivated under the condition of different phosphorus sources and pH value. GDH gene expression of strain wj1 was higher than the other under high phosphorus, and the result was opposite under phosphorus stress. However, GDH gene expression of strain wj3 was lower in all phosphorus levels. The expression of GDH gene and the change of the enzyme activity were not obviously related with phosphorus solubilizing capability for strain wj3. [Conclusion] There were different characteristics of GDH activity and GDH gene expression in two isolated strains that have different phosphate solubilizing mechanisms.