Burkholderia tropica express a glucose dehydrogenase PQQ-dependent under nutritional or energy stress

GARCÍA-FERREYRA G; BERNABEAU P; GUIDI V; GALAR M L; BOIARDI J L; LUNA M F

Mar del Plata

Congreso; VIII Congreso Argentino de Microbiología General; 2012

Sociedad Argentina de Microbiología General (SAMIGE).

Burkholderia tropica express a glucose dehydrogenase PQQ-dependent under nutritional or energy stress   García-Ferreyra G1, Bernabeu P1, Guidi V1, Galar ML1, Boiardi JL1 y Luna MF1*   1CINDEFI (UNLP; CCT-La Plata, CONICET), Facultad de Cs. Exactas. Calles 47 y 115. La Plata (1900). *CIC PBA   mafla@quimica.unlp.edu.ar     Several reports show the ability of different bacteria to solubilize inorganic phosphate compounds. Phosphate solubilizing bacteria (PSB) play an important role in supplementing phosphorus to the plants, allowing a sustainable use of phosphate fertilizers. The P-solubilizing ability of bacteria is attributed to the secretion of organic acids of low molecular weight. The best characterized mechanism of P-solubilization involves secretion of gluconic acid from oxidation of glucose by a periplasmatic pyrolloquinoline quinone-dependent glucose dehydrogenase (mPQQ-GDH). Gluconic acid secretion is normally constitutive in most PSB, except for some Erwinia species being induced by P deficiency. Burkholderia tropica strains have been reported to posses the ability to solubilize insoluble phosphates. This microorganism posses a glucose dehydrogenase (mGDH) responsible for the periplasmic conversion of glucose into gluconic acid, directly related with poorly soluble mineral phosphates solubilization. In the present work it was checked the ability of B. tropica Mto293 to express an active mGDH enzyme under different culture conditions and to require PQQ as cofactor. Batch cultures were carried out in bioreactor with glucose or glycerol as C-sources and different phosphate and nitrogen sources. B. tropica secreted high amounts of gluconic acid, which correlated with GDH activity, only at low P levels or under biological Nitrogen fixation, indicating the non-constitutive nature of GDH enzyme. However, cultures with soluble phosphate and ammonium as nitrogen source showed GDH activity after a pulse of PQQ. The results indicate that mGDH is active under nutritional or energy stress and it has a PQQ-dependence.