African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12258

Full Length Research Paper

Evaluation methods used for phosphate-solubilizing bacteria

Clayton Albuquerque Sousa
  • Clayton Albuquerque Sousa
  • Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Av. Dom Manuel de Medeiros s/n, 52171-900, Brazil.
  • Google Scholar
Mario de Andrade Lira Junior
  • Mario de Andrade Lira Junior
  • Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Av. Dom Manuel de Medeiros s/n, 52171-900, Brazil.
  • Google Scholar
Giselle Gomes Monteiro Fracetto
  • Giselle Gomes Monteiro Fracetto
  • Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Av. Dom Manuel de Medeiros s/n, 52171-900, Brazil.
  • Google Scholar
Fernando José Freire
  • Fernando José Freire
  • Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Av. Dom Manuel de Medeiros s/n, 52171-900, Brazil.
  • Google Scholar
Júlia Kuklinsky Sobral
  • Júlia Kuklinsky Sobral
  • Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Av. Dom Manuel de Medeiros s/n, 52171-900, Brazil.
  • Google Scholar


  •  Received: 01 October 2015
  •  Accepted: 16 August 2016
  •  Published: 24 August 2016

Abstract

Phosphorus solubilizers naturally acidify rhizospheric soil and increase phosphorus availability; therefore, their evaluation may help to reduce phosphorus fertilizer use. This work aimed to evaluate the different selection methods and select inorganic phosphorus-solubilizing bacteria as potential plant-growth promoters. Bacterial isolates obtained from sugarcane roots and soil were tested using solid growth media containing bicalcium phosphate and Irecê Apatite ground rock phosphate as phosphorus sources. Seven isolates with high (3), moderate (3) and low solubilization indices (1) and the Pseudomonas fluorescens R-243 strain were tested in two liquid growth media, followed by the pH and soluble P in the solution. The same isolates, in the absence of inoculation, were tested in Leonard jars with two high- and low-solubility sources using cowpea as a test species. Forty-four days after planting aboveground dry mass, the phosphorus content and total aboveground phosphorus and substratum phosphorus contents were evaluated. The growth media affected phosphorus solubilization by the bacteria. Evaluation of liquid media was the most reliable method for analyzing bicalcic phosphorus solubilization by the bacteria not linked to pH reduction. Isolates UAGC 17, 19 and 65 should be better studied because they were the best solubilizers in culture media; however, they did not demonstrate the same efficiency when inoculated on cowpea.

Key words: Solubilization, phosphate, P-solubilizing-microorganisms.