Characterisation and action mode of Gluconacin, a bacteriocin with antimicrobial activity against Xanthomonas albilineans

Abstract

Gluconacin, a bacteriocin produced by Gluconacetobacter diazotrophicus PAL5, has previously shown a large spectrum of inhibitory activity against beneficial and phytopathogenic bacteria. The present study proposes a three-dimensional (3D) structure for Gluconacin based on modelling and describes some physicochemical characteristics and the effect of the peptide on cells of the phytopathogenic bacterium Xanthomonas albilineans ICMP196. The Gluconacin 3D structural model results demonstrated the 7 αhelices and 11 β-sheets. Growth inhibition of the indicator microorganism, X. albilineans, occurred in the first moments of contact with Gluconacin (0.25 μg μl À1 ). Treatment of bacterial cells caused significant loss of inorganic phosphate and UV-absorbing materials.Scanning electron microscopy images showed that Gluconacin-treated X. albilineans cells were fully lysed. These results suggest that the mode of action of this peptide involves altered membrane integrity and increased permeability, resulting in complete cell lysis.Physicochemical characterisation demonstrated stability of biological activity under high temperatures, including autoclaving conditions and low pH. The activity was reduced after treatment with proteases and some surfactants and abolished with ethylenediaminetetraacetic acid (EDTA). The 3D conformation model indicates the possibility of a hydrophobic region, which could possibly interact directly with the cell membrane of target bacteria. In conclusion, the ability of Gluconacin to inhibit growth of phytopathogens of agricultural importance opens up new opportunities for biotechnological applications and, consequently, a reduction in the use of pesticides.

Molecular Characterization, Purification, and Mode of Action of Enterocin KAE01 from Lactic Acid Bacteria and Its In Silico Analysis against MDR/ESBL Pseudomonas aeruginosa

“…The activity was reduced when purified enterocin KAE01 FPLC fractions were exposed to proteases such as pepsin, trypsin, chymotrypsin, and proteinase K. Circular bacteriocins (head-to-tail-ligated cyclic antimicrobial peptides), including circularin A, Microcin J25, gassercin A, and AS-48, have been found to be extremely resistant to being broken down by some proteases [ 57 , 58 ]. The three-dimensional shape of these circular peptides may make recognition sites inaccessible, rather than the lack of enzyme digestion sites being the cause of this resistance.…”

Tyrosine Kinase Self-Phosphorylation Controls Exopolysaccharide Biosynthesis in Gluconacetobacter diazotrophicus Strain Pal5

“…Specific PCR primers were designed for the wzc gene (GDI2549) from G. diazotrophicus strain Pal5 and the MGD and MWzc mutants (Table 1). The E. coli expression system with Gateway ® technology (Thermo Fisher Scientific, Waltham, MA, USA) was applied to express the Wzc heterologous protein in E. coli strain BL21-AI™ using the suitable plasmids [34,35] and quantified [36]. The functionality of Wzc in different strains from G. diazotrophicus was tested by using heterologous expression in E. coli strain BL21-AI™.…”

The Effects of Gluconacin on Bacterial Tomato Pathogens and Protection against Xanthomonas perforans, the Causal Agent of Bacterial Spot Disease

“…Our group has been studying Gluconacin, a bacteriocin produced by Gluconacetobacter diazotrophicus strain PAL5. This antimicrobial peptide has demonstrated inhibitory activity against various sugarcane pathogens [ 19 ] and stability at high temperatures and acidic pH [ 20 ]. Therefore, it shows promising characteristics for ecological formulations and new sustainable agricultural practices.…”