Venenos e toxinas ofídicas purificadas como ferramenta biotecnológica para o controle de Ralstonia solanacearum

The objective of this work was to evaluate the in vitro antibacterial activity of snake venoms and purified toxins on the phytopathogenic bacterium Ralstonia solanacearum . The evaluations were performed with 17 crude venoms (13 from Bothrops , 3 from Crotalus , and 1 from Lachesis ) and seven toxins (1 from Bothrops and 6 from Crotalus ). Antibacterial activity was assessed in MB1 medium containing solubilized treatments (1 μL mL ‑1 ). A total of 100 μL bacterial suspension (8.4 x 10 9 CFU mL -1 ) was used. After incubation at 28°C, the number of bacterial colonies at 24, 48, and 72 hours after inoculation was evaluated. SDS-PAGE gel at 15% was used to analyze the protein patterns of the samples, using 5 μg protein of each sample in the assay. Furthermore, the minimum inhibitory concentration (MIC) and lethal concentration (LC 50 ) values were determined by the Probit method. Venoms and toxins were able to reduce more than 90% of R . solanacearum growth . These results were either equivalent to those of the positive control chloramphenicol or even better. While MIC values ranged from 4.0 to 271.5 µg mL -1 , LC 50 ranged from 28.5 µg mL -1 to 4.38 mg mL -1 . Ten crude venoms (7 from Bothrops and 3 from Crotalus ) and two purified toxins (gyroxin and crotamine) are promising approaches to control the phytopathogenic bacterium R . solanacearum .