ULTRA STRUCTURAL EVALUATION OF XANTHOMONAS ARBORICOLA PV. PRUNI TREATED WITH ANTIBIOTIC COMPOUNDS PRODUCED BY PSEUDOMONAS SP.

Fernanda Corrêa da Silva Vasconcellos (UEL); Admilton Gonçalves Oliveira Junior (UEL); Lucilene de Paula Lopes (UEL); Jamile Priscila de Oliveira Beranger (UEL); Flávia Regina Spago (UEL); Cintia Greice Matsuoca Góis (UEL); Suzana Sosa Coimbra (UEL); Galdino Andrade (UEL); Marco Antônio Nogueira (UEL); Osvaldo Capello (UEL); Juca Abramo Barrera San Martin (UEL); Celia Guadalupe Tardeli de Jesus Andrade (UEL); João Carlos Palazo Mello (UEM)

Bacterial spot disease of peach trees (Prunus persica) is caused by  Xanthomonas arboricola pv. pruni (Xap) and is of the most important disease for this specie, where the chemical control is not very efficient. Currently, the control of this disease is making by use of copper and/or antibiotics (streptomycin and tetracycline), which may cause bacterial resistance and contamination of the environment. The search for new alternative to control the disease is the challenge for scientific community and the use of extracellular bacteria compounds to control phytopatogenic bacteria introducing a new promising strategy. The objective of this work was to analyze ultra structural alterations of Xanthomonas arboricola pv. pruni treated with extracellular compounds (fraction F3) produced by Pseudomonas sp. For extraction of extracellular compounds was cultivated Pseudomonas sp. in the nutrient broth plus CuCl₂ (15 days, 28ºC, 150 rpm), after was realized the centrifugation (20 min, 4ºC, 9000 rpm), the supernatant free cells was washed with dichloromethane obtaining dichloromethane phase (DP), the DP was concentrated in rotavapor evaporator, freezed in a liquid nitrogen and lyophilized, the DP was fractionated by vacuum chromatography (VLC) using three organic solvents with crescent polarity. The fraction F3 obtained from VLC was tested against Xanthomonas arboricola pv. pruni (10⁸ CFU mL^-1) was grown in nutrient broth and treated with fraction F3 (200 mg mL^-1) during 1, 3, 6 hours, sterile distilled water was used as control. Samples were prepared for analysis in scanning electron microscope (FEI Quanta 200). The results showed that structural changes were observed in exopolysaccharide and cell morphology after 3 hours of treatment. Complete collapse of the bacterial cells occurred after 6 hours of expouse to the fraction F3. The antibacterial activity shown by fraction F3 suggests its potencial effect against infections caused by Xanthomonas arboricola pv. pruni.