Abstract
Nanoparticles (NPS) are considered as a new generation of compounds to improve environmental remediation and biological processes. The aim of this study is to investigate the effect of iron NPS encapsulated in porous silica (SiO2) on the biphenyl biodegradation by Rhodococcus erythropolis T902.1 (RT902.1). The iron NPS (major iron oxide FexOy form) were dispersed in the porosity of a SiO2 support synthesized by sol-gel process. These Fe/SiO2 NPS offer a stimulating effect on the biodegradation rate of biphenyl, an organic pollutant that is very stable and water-insoluble. This positive impact of NPS on the microbial biodegradation was found to be dependent on the NPS concentration ranging from 10-6 M to 10-4 M. After 18 days of incubation the cultures containing NPS at a concentration of 10-4 M of iron improved RT902.1 growth and degraded 35% more biphenyl than those without NPS (positive control) or with the sole SiO2 particles. Though the microorganism could not interact directly with the insoluble iron NPS, the results show that about 10% and 35% of the initial 10-4 M iron NPS encapsulated in the SiO2 matrix would be incorporated inside or adsorbed on the cell surface respectively and 35% would be released in the supernatant. These results suggest that RT902.1 would produce siderophore-like molecules to attract iron from the porous silica matrix.
Highlights
Bioremediation of polluted soils is considered as a more effective and sustainable method to remove pollutants than physico-chemical technologies
First we investigated the effect of calcined iron NPS added in the culture medium at concentrations ranging from 10−6 to 10−4 M the comparison of the impact of 10−4 M of calcined iron NPS and dried iron NPS was assessed
The results of this study have shown that the biphenyl biodegradation by RT902.1 is improved in the presence of the iron NPS encapsulated in porous silica
Summary
Bioremediation of polluted soils is considered as a more effective and sustainable method to remove pollutants than physico-chemical technologies. By contrast, when comparing to the kinetics achieved at 2.5 × 10−5 M of metal, Kotresha and Vidyasagar [9] reported a 2-fold decrease of phenol biodegradation rate by P. aeruginosa MTCC 4996 in presence of 2 × 10−4 M of cobalt or nickel and up to 1.5 × 10−3 M of copper, cadmium or zinc. These elements are heavy metals not suitable for environmental applications
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