NATIVE BACTERIUM WITH BIOCONTROL ACTIVITY AGAINST Xanthomonas spp

BIANCO, MI; MIELNICHUK, N; FELIPE, V; VOJNOV, AA; YARYURA, PM

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

Plant diseases caused by phytopathogenic species of Xanthomonas are currently controlled using copper compounds and resistant host varieties. However, the use of chemical products has failed to control plant diseases due to the appearance of resistant bacterial strains. Moreover, these compounds pollute the environment and can affect human and animal health. For these reasons, it is important to find alternative strategies to manage diseases caused by Xanthomonas. Nowadays, the use of beneficial microorganism for phytopathogens control is becoming common. Our aim is to find novel native bacteria with antagonistic activity against different species of Xanthomonas: X. citri subsp citri, X. campestris pv. campestris, X. vesicatoria, X. albilineans and X. sacchari. Until now, we isolated from tomato rhizosphere a bacterium (named TVM05) that antagonizes all the different strains of Xanthomonas considered in this study. TVM05 is a Gram-positive spore-forming bacillus. The antagonistic activity of TVM05 against Xanthomonas spp. was analyzed plating the phytopathogenic bacteria on tryptic soy agar and 30 μl of TVM05 free-cell supernatant (FCS) into 5 mm-wells. After incubation for 48 h at 28 ºC, inhibition growth area was analyzed using Image J32 program. Optimal activity of FCS was detected at early stationary phase. Besides, results showed that FCS was stable after heat treatment at 50 and 100 °C during 15 minutes (p<0.05) and conserved its activity when storage at 4 and -20 ºC for a month (p<0.05). These findings suggest that TVM05 is a good candidatefor biological control of Xanthomonas spp. Our next step is to purify the compound(s) responsible(s) for the antagonistic activity against Xanthomonas spp. and to carry out in plant assays to analyzed the effect of the purified antagonistic compound(s) on Xanthomonas.spp. virulence.