Different products use different biocides for preservation purposes. Among the currently available biocides, silver nanoparticles are widely used globally owing to their excellent antibacterial properties. For instance, the use of silver nanoparticles has highly increased over the past few years. Unfortunately, its production, use, and disposal have negative impacts on the environment. For example, it inhibits various essential processes like photosynthesis, biochemical and physiological processes. To this end, the negative impacts of silver nanoparticles on the environment have become a global concern among policymakers and stakeholders whose main aim is protecting the environment against pollution.
Generally, microbial denitrification is an important aspect of the nitrogen cycle. However, high levels of silver nanoparticles may result in incomplete denitrification that may further influence the nitrate reduction efficiency thus leading to global warming. Unfortunately, the effects of the silver nanoparticles on bacterial denitrification under anoxic conditions have not been fully explored. This will provide the necessary information required to protect the environment against the silver nanoparticles.
Presently, several approaches have been proposed to understand the bacterial growth and metabolism. In a recently published literature, the effects of protein synthesis on the microbial growth and metabolism have been given significant attention due to its important role in several biological processes. Furthermore, the analysis of transcriptional and proteomic profiling has been identified as a promising solution for investigating the mechanisms. Even though much has been revealed about the causes of the toxicity of the silver nanoparticles, complete transcriptional profile of denitrifying bacteria exposed to silver nanoparticles is yet to be clarified.
Recently, Dr. Xiong Zheng and his colleagues at State Key Laboratory of Pollution Control and Resource Reuse in Tongji University investigated the effects of silver nanoparticles on bacterial denitrification under anoxic conditions. The mechanism was based on a comprehensive analysis of transcriptional and proteomic profiling. Briefly, Paracoccus denitrificans were used in this case. Consequently, the transformation of denitrification intermediates like nitrogen oxide was also investigated while a set of expressed genes involved in denitrification were used to examine the underlying mechanisms. Furthermore, its effects on the growth and bacterial structures were also examined. Their work is published in the journal, Journal of Hazardous Materials.
The authors observed that the presence of the silver nanoparticles significantly inhibited the reduction of nitrates and nitrous oxide and thus bacterial denitrification. This was attributed to the attachment of the nanosilver on the surfaces of the bacterial cells. Consequently, the nanosilver influenced the expression of genes thus creating an unfavorable environment for denitrification processes. Furthermore, proteomic profiling and transcriptional profiling showed that the silver nanoparticles were responsible for inhibiting the synthesis of functional proteins involved in the various processes such as catalytic and metabolic.
The study successfully provided an in-depth understanding of the effects of silver nanoparticles on the bacterial denitrification. According to the authors, it will enable creating of measures to governing production, use and disposal of silver nitrates as a way of protecting the environment against pollution and global warming brought about by the release of silver nanoparticles.
Zheng, X., Wang, J., Chen, Y., & Wei, Y. (2018). Comprehensive analysis of transcriptional and proteomic profiling reveals silver nanoparticles-induced toxicity to bacterial denitrification. Journal of Hazardous Materials, 344, 291-298.Go To Journal of Hazardous Materials