UNA MUTACIÓN DEL GEN gltA EN UN AISLAMIENTO NATIVO DEL SUBGRUPO Pseudomonas chlororaphis GENERA PÉRDIDA DEL FENOTIPO ASOCIADO A LA PRODUCCIÓN DE FENAZINAS

AGARAS, B; WALL LG; VALVERDE C

Córdoba

Congreso; XI CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL SAMIGE; 2015

SAMIGE

Members of the Pseudomonas genus colonize the rhizosphere of different plant species and display plant-probiotic traits. Therefore, they are interesting candidates for biological agricultural inputs to stimulate plant development and/or promote crop health. We have generated a collection of 19 isolates of pseudomonads obtained from either bulk soil or the rhizosphere of major extensive crops from different plots under no-till management located in Argentina. Among this collection, the native isolate SPAN5 was obtained from a bulk soil sample of grasslands located at Pergamino, Buenos Aires. This isolate, related with the P. chlororaphis subgroup by its 16S rDNA, rpoB and oprF sequences, showed several PGPR activities in vitro: growth inhibition of 12 fungal pathogens in PDA plates; production of phospholipases, exoproteases and HCN; presence of genes related with antibiotic production (prnD for pyrrolnitrin, phzF for phenazines); inorganic phosphorous solubilization; and production of IAA and ACC deaminase. In particular, phenazines produced by SPAN5 confer it an orange colour in saturated cultures. We carried out Tn5 mutagenesis in order to identify genes related to the biocontrol and direct plant growth promotion potential. One of the isolated mutants, SPAN5-135, that has lost the orange pigmentation and can not grow in PDA plates, suffered transposon insertion in the gltA gene encoding a type II citrate synthase. This is the first report of the requirement of gltA for phenazine production in pseudomonads. Further characterization of the antifungal activity and PGPR traits of the colourless-SPAN5 Tn5 mutant is underway.