Phosphate solubilization potentials of soil Acinetobacter strains

Ogut M., Er F., Kandemir N.

Biology and Fertility of Soils, vol.46, no.7, pp.707-715, 2010 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 46 Issue: 7
  • Publication Date: 2010
  • Doi Number: 10.1007/s00374-010-0475-7
  • Journal Name: Biology and Fertility of Soils
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.707-715
  • Keywords: Acinetobacter, Phosphate solubilization, Pyrroloquinoline quinone (PQQ)
  • Ankara Haci Bayram Veli University Affiliated: No


Many phosphate solubilizing microorganisms (PSM) require external pyrroloquinoline quinone (PQQ) for strong phosphorus (P) solubilization in vitro. The objective of this study was to isolate efficient and PQQ-independent PSM. A total of 21 PSM were isolated from the rhizosphere soil of wheat and maize grown in the pots. Acinetobacter strains were the only PQQ-independent and most effective solubilizers of tricalcium phosphate containing agar. The mean P dissolved in liquid cultures of Acinetobacter strains in a 5-day incubation ranged from 167 to 888 μg/ml P. The pH dropped to below 4. 7 from 7. 8 in six isolates, which produced gluconic acid in concentrations ranging between 27. 5 and 37. 5 mM. There was a linear regression between soluble P and gluconic acid concentrations in the bacterial cultures (P < 0. 05; R2 = 0. 59). Inoculation with Acinetobacter sp. WR922 significantly (P < 0. 05) increased wheat (Triticum aestivum L.) P content by 27% at 15 days after emergence (DAE) and dry matter by 15% at 30 DAE compared to the control. The plant P content in inoculated plants at 30 DAE was linearly correlated with soluble P of the bacterial cultures (P < 0. 05; R2 = 0. 69). Gluconic acid production directly affected phosphate solubilization in vitro, which in turn influenced plant P content of inoculated plants in PQQ-independent P-solubilizing Acinetobacter strains. © 2010 Springer-Verlag.