A GacS deficiency affects bacteriocin production in Pseudomonas putida MGR37

CORDERO, PV; PRÍNCIPE, A.; GODINO, A; MEDEOT, D.B.; JOFRE, E.; MORI, G; FISCHER, S.E.

Congreso; XLVIII Reunión Anual SAIB; 2012

The plant growth-promoting rhizobacterium, Pseudomonas putida MGR37 secretes bacteriocins which kill a wide range of bacteria related to the Pseudomonas genus. The aim of this work was the identification of genetic determinants involved in the production of such compounds. In this sense, a collection of P. putida MGR37 mutants was generated by Tn5-B21 mutagenesis and screened by the inability to produce antimicrobial compounds. An isogenic Tn5-B21 mutant that had lost the capacity to inhibit the growth of Pseudomonas fluorescens CTR212 was selected and further characterized. This mutant, designated 646 carries a single transposon insertion into an ORF homologous to a gacS gene from several members of Pseudomonas genus. This gene encodes for a histidin kinase sensor of the two-component system GacA/GacS. In addition, the mutant 646 showed a cell phenotype of non-attached aggregates and a diminished in the biofilm formation. These results suggest that a mutation in the gacS gene affects a variety of phenotypes which are important for the bacterial competitiveness within the environmental. Complementation assays are being carried out to demonstrate the implication of the two-component system GacS/GacA in the production of antibacterial compounds such as bacteriocins.