Solubilization of different sources of insoluble phosphate by Gluconacetobacter diazotrophicus

Abstract

The aim of this work was to assess the phosphorus-solubilizing capacity of Gluconacetobacter diazotrophicus under different sources of insoluble phosphate (Pi), using the wild-type strain PAL5 and its Tn5-derivative mutants
(K416, 16D10 and 16G6) defectives in organic acids production. Pi solubilization capacity was assessed in NBRIP solid minimal medium, supplemented with different Pi-insoluble sources, by the determination of the solubilization
index (SI). The PAL5 strain solubilized all the Pi-sources used herein, with different degree of SI, confirming the Pi-solubilizer status for G. diazotrophicus. K416 and 16G6 mutants were able to solubilize some of the Pi sources
tested although with less ability, compared to PAL5. 16D10 was completely unable to solubilize any Pi source tested. Further studies are necessary to perform in order to investigate the participation of G. diazotrophicus and
its derivative mutants in the bacterial Pi-metabolism and in association to plants as growth promoters.