Gluconacin from Gluconacetobacter diazotrophicus PAL5 is an active bacteriocin against phytopathogenic and beneficial sugarcane bacteria

Aims This study aimed to explore the possibility of using the Gluconacin from Gluconacetobacter diazotrophicus strain PAL5 in the biological control of diverse sugarcane phytopathogenic bacteria. Methods and Results An in silico analysis was first employed to determine the phylogenetic relationship between Gram-negative/positive bacteriocin producers and Gluconacin. The analysis showed that this trait is widespread among tested bacterial species and a well-conserved gene within the Acetobacteraceae family. The bacteriocin gene (GDI_0415) present in the genome of strain PAL5 was than cloned in pDEST (TM) 17 and expressed in Escherichia coli BL21-AI (TM). A bioassay showed growth inhibition of Xanthomonas albilineans by the recombinant bacteriocin. Subsequent bioassays indicated different levels of antagonistic activity against the majority of the sugarcane phytopathogenic bacteria (Xanthomonas axonopodis pv. vasculorum, Acidovorax avenae subsp. avenae, Pseudomonas syringae pv. syringae, Xanthomonas vasicola pv. vasculorum). In addition, the bacteriocin was also antagonistic to some beneficial bacterial strains belonging to G. diazotrophicus and endophytic Bacillus species, which also colonize sugarcane plants. Conclusions The GDI_0415 gene, responsible for the production of Gluconacin, is well conserved within the Acetobacteraceae family and presented antagonistic activity against phytopathogenic and a few beneficial sugarcane bacteria. Significance and Impact of the Study The production of a recombinant protein, named Gluconacin, opens new avenues for the agro-biotechnology application in agriculture, mainly with regard to the sugarcane crop.