2-Ketogluconic Acid Production and Phosphate Solubilization by Enterobacter intermedium

Abstract

Enterobacter intermedium, isolated from grass rhizosphere, exhibited a strong ability to solubilize insoluble phosphate. This bacterium oxidized glucose to gluconic acid and sequentially to 2-ketogluconic acid (2-KGA), which was identified using HPLC and GC-MS. The ability of E. intermedium to solubilize phosphate and produce 2-KGA produce in broth medium containing different components was monitored with air and without air supply. With an air supply, the production of 2-KGA markedly increased to about 110 g/l at day 10 in media containing 0.2 M gluconic acid, while it was about 65 g/l without gluconic acid addition. With an air supply, the concentration of soluble phosphate significantly decreased to 200-250 mg/l in media containing 1% CaCO3, whereas it was about 1000 mg/l without CaCO3 addition. Without an air supply, the concentration of 2-KGA and phosphate were negligible throughout the culture period.

Isolation of Phosphate-Solubilizing Fungi from Phosphate Mines and Their Effect on Wheat Seedling Growth

“…A strong negative correlation (r=-0.89; p<0.01) between the content of soluble phosphorus and pH was observed. It was accordance with some studies which also showed a negative correlation between soluble phosphorus released and pH in phosphate solubilization [21,22].…”

Pseudomonas lurida M2RH3 (MTCC 9245), a psychrotolerant bacterium from the Uttarakhand Himalayas, solubilizes phosphate and promotes wheat seedling growth

“…Bacterial mineral phosphate solubilization has been attributed to the activity of glucose dehydrogenase; a membrane bound enzyme that is involved in the direct oxidation of glucose to gluconic acid, which subsequently gets converted to 2-ketogluconic acid and 2, 5-diketogluconic acid (Goldstein 1995). The 2-ketogluconic acid is more effective than gluconic acid in solubilizing phosphate (Kim et al 2002). In a dramatic shift from the past, there has been a surge of interest on P solubilization at cold temperatures by natural and mutant psychrotolerant strains in the present decade (Katiyar and Goel 2003;Trivedi and Sa 2007).…”

Phosphate solubilization and growth promotion by Pseudomonas fragi CS11RH1 (MTCC 8984), a psychrotolerant bacterium isolated from a high altitude Himalayan rhizosphere

“…Subsequently gluconic acid is enzymatically converted to 2-ketogluconic acid and 2,5-diketogluconic acid. The 2-ketogluconic acid is more effective than gluconic acid in solubilizing phosphate (Kim et al 2002). While most earlier studies on this phenomena were restricted to mesophilic temperatures (Chung et al 2005;Chen et al 2006), recent studies have shifted the focus to P solubilization by mutant strains at the psychrotolerant range (Katiyar & Goel 2003; a Values are the mean of ten replicates.…”