Green extracellular synthesis of the Fe2O3 nanoparticles by a native marine bacterium, Alcaligenes sp. strain NV06

This study investigated the potential of aquatic bacteria for their ability as a biocatalyst to synthesized Fe2O3 nanoparticles using iron precursor, FeCl3. A total of 25 aquatic bacterial strains were isolated in trypticase soy agar plus 10 mM FeCl3 with selective enrichment technique. Among the bacterial strains evaluated, NV06 was the only strain able to synthesize Fe2O3 nanoparticles extracellularly. The strain NV06 was identified as Alcaligenes sp., on the basis of phenotypic and molecular characteristics. Extracellular synthesis of Fe2O3 nanoparticles by this strain was investigated under the optimal conditions. The biosynthesized Fe2O3 nanoparticles were characterized using UV–visible spectrophotometry (UV-Vis), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FTIR) spectroscopy. The results showed that cell-free extract (CFE) of the bacterium strain can produce the rod-shaped Fe2O3 nanoparticles with mean edge lengths of 80.2 nm and mean diameters of 25.5 nm, after being exposed to FeCl3 solution (10 mM), at an optimum pH of 6 and an optimum temperature of 28 °C, after 96 hours of incubation at 150 rpm. This is the first report on the extracellular biosynthesis of Fe2O3 nanoparticles using the genus of Alcaligenes under the CFE strategy. It could be speculated that the results of the study can hopefully introduce the inherent capabilities of aquatic microbes as safe, simple, and effective biocatalysts in the production of Fe2O3 nanoparticles.