Siderophores production and in vitro antifungal activity of two plant growth promoting bacteria: Gluconacetobacter diazotrophicus and Burkholderia tropica

ORMAZABAL, CELESTE; BERNABEU, PAMELA; CAVELLO, IVANA; LUNA, FLAVIA

Rosario

Congreso; IX Congreso Argentino de Microbiologia General -SAMIGE-; 2013

In the last decades there has been an increased interest in the use of Plant Growth PromotingBacteria (PGPB) for biological control as an alternative to reduce the population of phytopathogenic organisms and to decrease the use of chemicals in agriculture. It has been demonstrated that PGPB can exert this function by diverse mechanisms such as competition for an ecological niche or a substrate, production of inhibitory allelochemicals and induction of systemic resistance in host plants to a broad spectrum of pathogens. Two N2-fixing endophytic bacteria, Gluconacetobacter diazotrophicus Pal 5 and Burkholderia tropica MTo293, were described as potential PGPB, but their capabilities as biocontrol agents have been poorly characterized. In this way, batch cultures with these bacteria growing independently under different nutritional conditions were carried out to evaluate siderophores production and, on the other hand, plate assays were made using different phytopathogenic fungi in order to determinate their abilities to inhibit fungal growth. Both microorganisms produced siderophores under iron depletion, independently of other nutritional conditions. Six fungi strains were tested and both microorganisms showed growth inhibition against Fusarium gramineae (Fusarium head blight) and Alternaria alternata (diseases on tomato and others). These results show that the PGPB tested in this work are promising for their use as biocontrol agents of plant diseases. Future studies will be necessary to find the nature of the biological products (siderophores or others) that produce this inhibition, and antifungal activity should be tested in vivo to support these results.