Extremophilic Enzymatic Response: Role of Proteins in Controlling Selenium Nanoparticle Synthesis.

摘要

We have studied a thermophilic bacteria GWE1 belonging to Geobacillus genus able to biosynthesize Se0 nanoparticles. Elemental analysis and composition of the particles were verified using transmission electron microscopy and energy-dispersive X-ray analysis. The nanoparticles have a defined spherical shape and are composed by Se0. Previous experiments showed that the presence of the whole microorganism for the reduction of selenite was not necessary. We have isolated an intracellular NADPH/NADH-dependent reductase which mediates selenium nanoparticles synthesis under aerobic conditions. The enzyme was purified and identified as a 1-pyrroline-5-carboxylate dehydrogenase by mass spectroscopy MALDI-TOF TOF technique. FT-IR analysis was utilized to characterize the chemical surface of Se nanoparticles. These results strongly suggest that the biosynthesis of Se nanoparticles is mediated by NADH-dependent enzymes. This ecologically-friendly process allows an efficient control of size, shape and composition of the generated particles. Additionally biosynthesized nanoparticles display good surface bioactivity.