Biosynthesis of copper nanoparticles by Stenotrophomonas maltophilia

Heavy metals are environmentally sustainable and durable pollutants that have become a world problem. As microorganisms show high resistance to heavy metals and can purify the environment and produce nanoparticles, the present study was designed to produce copper nanoparticles from copper-resistant bacteria isolated from wastewater of two copper workshops in Isfahan.
In this cross-sectional study, wastewater samples were collected from two copper workshops in Isfahan. The physicochemical factors of the wastewater, the minimum inhibitory concentration of bacteria (MIC) to copper and their resistance to several antibiotics were investigated. Morphological, biochemical and molecular identification tests were carried out on samples. Then the biomass of copper-resistant bacteria was added to the copper sulfate pentahydrate stock (CuSO4.5H2O) and the results were evaluated by Ultraviolet-Visible
spectrophotometer (UV-VIS), X-ray diffraction (XRD) and Transient Electron Microscopy (TEM).
Among the studied bacteria, the Bacillus toyonensis strain NE2 with the MIC of 3.5 mM and Arthrobacteragilis NE1 with MIC of 4 mM from copper workshop 2 and Stenotrophomonas maltophilia strain 5633 with the MIC of 6 mM from copper workshop 1 were isolated. Among these isolates, only S. maltophilia strain 5633 was able to synthesize copper nanoparticles. Peaks created in the range of 250-430 nm confirmed the presence of Copper (Cu) and Copper Oxide (CuO) particles.
The findings of this study showed that the isolated bacteria could be a good candidate to remove copper from wastewater and to biosynthesize copper nanoparticle.