اثر ضد باکتریایی نانوذرات نقره بیوسنتز شده، کیتوزان و ترکیب آنها بر باکتری های عامل آتشک و شانکر گوجه فرنگی

Bacterial diseases such as fire blight and canker of tomato annually cause considerable damage to pome fruit trees and tomatoes and reduce yield of these important economic plants. The need for safe and environmentally friendly control methods has led to the upsurge in the research on metal nanoparticles and their potential application in the management of plant bacterial diseases that metal nanoparticles in addition to plant protection against pathogenic agents, increase yield crops. Among different types of nanoparticles in this study, the antibacterial properties of silver nanoparticles synthesized using sumac extracts, chitosan with a solubility degree of more than 75% and their composition on Erwinia amylovora, causal agent of fire blight (Gram negative bacterium) and Clavibacter michiganensis subsp. michiganensis (Cmm), causal agent of tomato canker (Gram positive bacterium), were investigated by minimum inhibitory concentration (MIC) method in laboratory conditions. The death time of bacteria was determined with NCCLS method (National Committee on Clinical Laboratory Standards). Based on the results, spherical silver nanoparticles were synthesized with the average size of 35 nm which their minimum inhibitory concentration for E. amylovora and Cmm were 20 ppm and 13 ppm, respectively. The MIC of chitosan was 0.2 ppm and 0.1 ppm for E. amylovora and Cmm. The MIC of silver nanoparticles-chitosan composition was concentrations 2 ppm-2.63 ppm in E. amylovora and 3 ppm-6.94 ppm in Cmm. The death time of bacteria in all tests was immediately after mixing the nanoparticles with suspension of bacteria. According to this research, chitosan had the best antibacterial activity and its MIC for two types of bacteria was at very low concentrations. Also, the MICs of silver nanoparticles and chitosan were for cmm (Gram positive bacterium) lower than E. amylovora. In combination of silver nanoparticles with chitosan, the antibacterial activity of silver nanoparticles improved in two types of bacteria. Since nanoparticles in the ecosystem cycle exhibit the lowest toxicity levels, and due to easy, fast and cost-effective synthesis, are recommended in the management of plant bacterial diseases after supplementary studies.