%0 Journal Article
%T Mineral phosphate solubilization activity of gluconacetobacter diazotrophicus under P-limitation and plant root environment
%A J. M. Crespo
%A J. L. Boiardi
%A M. F. Luna
%J Agricultural Sciences
%P 16-22
%@ 2156-8561
%D 2011
%I Scientific Research Publishing
%R 10.4236/as.2011.21003
%X The ability to solubilize insoluble inorganic pho- sphate compounds by Gluconacetobacter 
diazotrophicus was studied using different cul-ture approaches. Qualitative plate assays using tricalcium phosphate as the sole P-source showed that G. diazotrophicus produced solu-bilization only when aldoses were used as the C-source. Extracellular aldose oxidation via a pyrroloquinoline quinone-linked glucose dehy-drogenase (PQQ-GDH) is the main pathway for glucose metabolism in G. diazotrophicus. In batch cultures with 5 g l-1 of hydroxyapatite as the P-source and glucose as the C-source, more than 98% of insoluble P was solubilized. No solubilization was observed neither using glyc-erol nor culturing a PQQ-GDH mutant of G. di-azotrophicus. Solubilizaton was not affected by adding 100 mmol l-1 of MES buffer. Continuous cultures of G. diazotrophicus showed significant activities of PQQ-GDH either under C or P limi-tation. An intense acidification in the root envi-ronment of tomato and wheat seedlings inocu-lated with a G. diazotrophicus PAL5 was ob-served. Seedlings inoculated with a PQQ-GDH mutant strain of G. diazotrophicus showed no acidification. Our results suggest that G. di-azotrophicus is an excellent candidate to be used as biofertilizer because in addition to the already described plant growth-promoting abili-ties of this organism, it shows a significant mineral phosphate solubilization capacity.
%K Gluconacetobacter Diazotrophicus
%K Phosphate Solubilization
%K Glucose Dehydrogenase
%K Pqq
%K Bio-fertilizer
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=3850