Abstract:
Pantoea agglomerans DSM3493 was isolated from green house soils collected from Chungchugnam-do
province, Gongju-Gun area in South Korea and phosphate solubilization and organic acid production of the
strain were assessed using three types of insoluble phosphate sources (Ca phosphate, Fe phosphate and Al
phosphate) under three different pH conditions (7, 8 and 9). The highest Ca phosphate solubilization (651 µg
mL-1) was recorded at pH 7 followed by pH 8 and 9 (428 and 424 µg mL-1 respectively). The solubilization rate
was found to be 80.4, 98.1 and 88.7 µg mL-1 (for Fe phosphate containing medium) and 9.3, 12.1 and 29.8 µg
mL-1 (for the Al phosphate containing medium) respectively at pH 7, 8 and 9. Though increasing pH of the
medium caused reduction in the rate of solubilization of Ca phosphate, solubilization of Fe and Al phosphates
enhanced with increasing pH. By contrast, the highest amount of organic acid was produced with Ca
phosphate while the lowest was recorded with the presence of Al phosphate. Among the organic acids,
gluconic acid production was found to be the highest, followed by oxalic acid and citric acid regardless the
source of phosphate. Results can thus be concluded that the production of organic acids appears to play a
significant role in the inorganic phosphate solubilization.
