Molecular genetic identification of yeast strains isolated from egyptian soils for solubilization of inorganic phosphates and growth promotion of corn plants

J Microbiol Biotechnol. 2011 Jan;21(1):55-61. doi: 10.4014/jmb.1006.06045.

Abstract

Forty yeast strains isolated from soils taken from different locations in Egypt were tested for their P-solubilizing activities on the basis of analyzing the clear zone around colonies growing on a tricalcium phosphate medium after incubation for 5 days at 25degreesC, denoted as the solubilization index (SI). Nine isolates that exhibited P-solubilization potential with an SI ranging from 1.19 to 2.76 were genetically characterized as five yeasts belonging to the genus Saccharomyces cerevisiae and four non-Saccharomyces, based on a PCR analysis of the ITS1-26S region amplied by SC1/SC2 species-specific primers. The highest Psolubilization efficiency was demonstrated by isolate PSY- 4, which was identified as Saccharomyces cerevisiae by a sequence analysis of the variable D1/D2 domain of the 26S rDNA. The effects of single and mixed inoculations with yeast PSY-4 and Bacillus polymyxa on the P-uptake and growth of corn were tested in a greenhouse experiment using different levels of a phosphorus chemical fertilizer (50, 100, and 200 kg/ha super phosphate 15.5% P2O5). The results showed that inoculating the corn with yeast PSY-4 or B. polymyxa caused significant increases in the shoot and root dry weights and P-uptake in the shoots and roots. The P-fertilization level also had a significant influence on the shoot and root dry weights and P-uptake in the shoots and roots when increasing the P-level from 50 up to 200 kg/ha. Dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 200 kg/ha gave higher values for the shoot and root dry weights and P-uptake in the shoots and roots, yet these increases were nonsignificant when compared with dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 100 kg/ha. The best increases were obtained from dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 100 kg/ha, which induced the following percentage increases in the shoot and root dry weights, and P-uptake in the shoots and roots; 16.22%, 46.92%, 10.09%, and 31.07%, respectively, when compared with the uninoculated control (fertilized with 100 kg/ha).

MeSH terms

  • Bacillus / metabolism
  • DNA, Fungal / genetics
  • DNA, Ribosomal / genetics
  • Egypt
  • Molecular Sequence Data
  • Phosphates / metabolism*
  • Phosphorus / metabolism
  • Phylogeny
  • Plant Roots / growth & development
  • Plant Roots / metabolism
  • Plant Roots / microbiology
  • Soil Microbiology*
  • Yeasts / classification
  • Yeasts / genetics
  • Yeasts / isolation & purification*
  • Yeasts / metabolism*
  • Zea mays / growth & development*
  • Zea mays / metabolism
  • Zea mays / microbiology

Substances

  • DNA, Fungal
  • DNA, Ribosomal
  • Phosphates
  • Phosphorus

Associated data

  • GENBANK/HM165257