Isolation and characterization of mineral phosphate-solubilizing bacteria naturally colonizing a limonitic crust in the south-eastern Venezuelan region

• Published in: Soil biology & biochemistry Vol. 39; no. 11; pp. 2905 - 2914
• Main Authors: Pérez, Elizabeth, Sulbarán, Miguel, Ball, María M., Yarzábal, Luis Andrés
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-11-2007; New York, NY Elsevier Science
• Subjects: acid soils; Agronomy. Soil science and plant productions; bacterial colonization; Biochemistry and biology; Biological and medical sciences; Burkholderia; Chemical, physicochemical, biochemical and biological properties; detection; Fundamental and applied biological sciences. Psychology; GDH; genes; Iron-rich acidic soils; Phosphate solubilization; Phosphate-solubilizing bacteria; phosphorus; Physics, chemistry, biochemistry and biology of agricultural and forest soils; polymerase chain reaction; Ralstonia; screening; sequence analysis; Serratia; soil bacteria; soil crusts; Soil science; solubilization; tricalcium phosphate; Venezuela; South America; America; Phosphate-solubilizing bacteria; GDH; Phosphate solubilization; Iron-rich acidic soils; Phosphates; Crust; Acid soil; Tropical zone; Iron; Bacteria; Soil science; Microbial solubilization; Limonite; Colonization
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2007.06.017

With the aim to explore the possible role of mineral phosphate-solubilizing bacteria (PSB) in phosphorus (P) cycling in iron-rich, acidic soils, we conducted a survey of PSB naturally colonizing a limonitic crust in the south-east region of Venezuela (Bolívar State). A total of 130 heterotrophic bacterial isolates showing different degrees of mineral tri-calcium phosphate (Ca
3(PO
4)
2)-solubilizing activities were isolated from NBRIP plates. In contrast, no isolates showing iron phosphate (FePO
4)- or aluminum phosphate (AlPO
4)-solubilizing activities were detected by this experimental approach. The 10 best Ca
3(PO
4)
2-solubilizers were selected for further characterization. These isolates were shown to belong to the genera
Burkholderia,
Serratia,
Ralstonia and
Pantoea by partial sequencing analysis of their respective 16S rRNA genes. All the PSB isolates were able to mediate almost complete solubilization of Ca
3(PO
4)
2 in liquid cultures; in contrast, the PSB isolates were less effective when solubilizing FePO
4. Two groups of PSB isolates were clearly differentiated on the basis of their Ca
3(PO
4)
2 solubilization kinetics. Acidification of culture supernatants seemed to be the main mechanism for P solubilization. Indeed, gluconic acid was shown to be present in the supernatant of five isolates. Furthermore, detection of genes involved in the production of this organic acid was possible in three isolates by means of a PCR protocol.