Eucalyptus species extracts inhibiting in vitro growth of the phytobacterium Xanthomonas campestris pv. campestris

Abstract

This study was carried out to evaluate the antibacterial potential of Eucalyptus spp. against two strains of the plant pathogenic bacterium Xanthomonas campestris pv. campestris (Xcc). The treatments consisted of aqueous and hydroethanolic extracts, at concentrations of 50% (experiment 1) and 35% and 15% (experiment 2), which were studied by the double layer inhibition test. The evaluated species were E. camaldulensis, E. cloeziana, E. grandis, E. “urograndis” and E. urophylla. Based on the results of experiment 1, it was observed that most of the extracts that inhibited the growth of the bacterial strains tested were hydroethanolic, except for the aqueous extract of the E. “urograndis” hybrid. Regarding experiment 2, it was observed that the greatest inhibition was with the concentrated extracts (35%), but the difference for the antibacterial effect was not significant in this case. Comparing the experiments, it was observed that in general the concentrated extracts (50%) had greater inhibition than the diluted ones. These results represent the potential of aromatic plants in the ecological management of Xcc, with emphasis on the aqueous and hydroethanolic extracts of E. cloeziana. Subsequently, bioassays will be performed to verify the effectiveness of such extracts in vivo.