Bacillus licheniformis, Pseudomonas fluorescens and Terribacillus saccharophilus isolated from grape roots produce GA1 in chemically-defined cultures

SALOMON M.V.; BOTTINI R.; PICCOLI P.

Tarragona

Conferencia; 20th IPGSA International conference on plants growth substances; 2010

Although grape is the fruit of major economic importance worldwide, few microbiological studies of soil and roots have been reported for the species. Plant growth promoter bacteria are inoculated into many crop species with the aim to increase yield. One mechanism by which bacteria can produce such a benefit for the plant is the production of phytohormones, namely IAA, gibberellins and ABA. We isolated and characterized by 16S rRNA gene sequences analysis several bacteria from soil adjacent and roots of Vitis vinifera L. cv. Malbec, among them Bacillus licheniformes, Pseudomonas fluorescens and Terribacillus saccharophilus. The aim of this study was to evaluate the ability of these three bacteria to produce phytohormones in chemically defined media. The cultures were grown 5 days in NFB modified medium, controlling OD540 (total biomass) and CFU ml-1 (cells alive). Although bacterial mass grew along the time, the number of cells alive was reduced towards the end in all the cultures. At this time only GA1 was characterized by GC-EIMS, but not IAA, ABA or GA3 as it has been reported for the genus Azospirillum and other rhizobacteria under similar conditions and by MS method. By using isotopically-labeled GA1 the amounts produced were calculated in 0.86, 0.61 and 0.96 ng.mL-1 of culture for B. licheniformis, P. fluorescens and T. saccharophilus, respectively. This is the first report of phytohormonal production by indigenous bacteria isolated from grape roots and adjacent soil.