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Effect of silver nanoparticles on Oryza sativa L. and its rhizosphere bacteria
Link to Journal Abstract
Silver nanoparticles (AgNPs) are widely used as antibacterial and antifungal agents in agriculture. Nevertheless, these nanoparticles with newborn properties pose a potential risk to the environment, Due to contact with crops and bacteria that are beneficial to the soil. This study is based on the examination of the phytotoxic effects of AgNPs on Oryza sativa L. and some of its rhizosphere bacteria, by physiological and biochemical assays. In order to study the complex interaction of the AgNPs life expectancy that are mixed with culture medium, the incubation time for the fresh mixture, 7, 14 and 21 days old of AgNPs, on the seedlings growth was investigated. Results indicated that plant’s response to the treatment with AgNPs affected on the cell wall, and that with an increase in its concentration (up to 60 ìg/mL). The obtained results of transmission electron microscopy (TEM) exhibited that those particles not only penetrated the cell wall, but they could also damage the cell morphology and its structural features. AgNPs treatment up to 30 ìg/mL accelerated root growth and at 60 ìg/mL was able to restrict a root’s ability to grow. The 30 ìg/mL treatment had significant effect on root branching and dry weight. In contrast, shoot growth was more susceptible to the effects of AgNPs treatment. The root content for total soluble carbohydrates and starch demonstrated that despite stable starch content, total soluble carbohydrates showed the tendency to significantly decline in response to AgNPs. However, induction of root branching and photosynthetic pigments can attributed to AgNPs stress based on evidence from the production of the reactive oxygen species (ROS) and local root tissue death. Nine isolates of the genus Bacillus selected and identified according to morphological and chemotaxonomic methods. The AgNPs treatment revolutionized the populations of bacteria as Bacillus thuringiensis SBURR1 was totally eliminated, and Bacillus amyloliquefaciens SBURR5 became the most populated one. Images from an electron microscope and the leakage of reducing sugars and protein through the bacterial membrane, similarly confirmed the “pit” formation mechanism of the AgNPs. Moreover the hypothesis from the growth curve study demonstrated that AgNPs may damage bacterium cell wall and transform them to protoplasts.
This study is based on the examination of the phytotoxic effects of silver nanoparticles (AgNPs) on Oryza sativa L. and some of its rhizosphere bacteria, by physiological and biochemical assays.
Peer Reviewed Journal Article
Exposure Or Hazard Target
Method Of Study
Environmental Fate and Transport
Risk Exposure Group
Ecotoxicology and Environmental Safety, 88: 48-54 (February 2013)
Ecotoxicology and Environmental Safety
Mirzajani F, Askari H, Hamzelou S, Farzaneh M, Ghassempour A
Last updated on February 12, 2013
This work is supported in part by the Nanoscale Science and Engineering Initiative of the National Science Foundation
under NSF Award Number EEC-0118007.
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