THE INFLUENCE OF LIGHT ON THE BIOSYNTHESIS OF PT AND AU NANOPARTICLES BY SHEWANELLA ONEIDENSIS MR-1

Shewanella oneidensis MR-1 is a metal-reducing bacterium widely used in dissimilatory reduction and recovery of precious metals. It has previously been used for the photo-induced reduction of Au(III) to Au(0), but to date there are no reports for the photo-induced reduction of Pt(IV). This study investigated whether light could be used to stimulate the synthesis of Pt nanoparticles (PtNPs) in S. oneidensis MR-1. The synthesis of AuNPs and PtNPs by S. oneidensis MR-1 both at dark and under white light was verified by UV-Vis spectroscopy and transmission electron microscopy (TEM). The results indicated that light significantly influences the synthesis of both Au and Pt nanoparticles. Under light conditions, the synthesis of AuNPs and PtNPs was induced within 24 hours, and the concentration increased exponentially over time. While being exposed to dark conditions, the reduction appeared to be a slower process (i.e., 48 hours for Au and more than 72 hours for Pt). The size and cellular localization of the NPs synthesized in above mentioned conditions also differed. To the best of our knowledge, this is the first report that the synthesis of PtNPs by S. oneidensis MR-1 can be induced by light, which could be a cost-effective and an environmentally friendly alternative to chemical synthesis.