ISOLATION AND CHARACTERIZATION OF ZN SOLUBILIZING BACTERIA FROM RICE RIZHOSPHERE IN ENTRE RIOS, ARGENTINA

ANDY SALAZAR TAMAYO; MAIALE, SANTIAGO JAVIER; ANDRES ALBERTO RODRIGUEZ; FERNANDO MATIAS ROMERO

Jornada; I Jornadas Científicas INTECH; 2023

Rice in Argentina is mainly produced in Entre Ríos and Corrientes provinces, which account for more than 80% of national production. In Entre Ríos, the crophas limitations due to several stresses, among them stands out the Zn deficit. We proposed the study of zinc solubilizing bacteria isolated from the ricerhizosphere, as an alternative to increase the rice production in the area and to reduce chemical fertilization. Solubilizing bacteria were isolated on mediumwith an insoluble Zn source (Zn 3 (PO 4 )2 ) after enrichment in liquid medium. To confirm the solubilizing capacity, pH and soluble Zn were determined by theZincon® method in culture medium. Phosphorus solubilization was also evaluated in NBRIP medium. Through this process, we obtained a collection of 99isolates on medium with the insoluble Zn source. 15 isolates were selected from these 99 bacterial isolates based on their ability to decrease the pH of themedium (pH2-6) and to show higher Zn solubilization (100-500ppm). To determine their potential as solubilizers of other Zn sources, the solubilizing capacitywas also evaluated in both solid (qualitative) and liquid (quantitative) medium using ZnO as an insoluble source. In all cases, the ability to solubilize both Znsources was observed. The isolate 64 showed the highest values in ZnO solubilization (400-600 ug/ml); the isolate 65 was the less effective with valuesbetween 100 and 300 ug/ml. Likewise, the ability of the isolates to solubilize an insoluble source of phosphorus (Ca₃(PO₄)₂) was also detected anddetermined. In this case, 12 out of 15 isolates were able to solubilize phosphorus, the highest rates were obtained for isolates 64 (1.5-2) and 76 (2-3). Theseisolates are currently being molecularly characterized and identified. Other plant-growth promotion traits such as indole and siderophore production are alsobeing carried out. In conclusion, this work shows different bacterial isolates with the capacity to solubilize Zn and P, that could be used as bioinoculants forrice cultivation to reduce the use of chemical fertilizers