Synthesis analysis and antibacterial activity of selenium nanoparticles produced by Pseudomonas alcaligenes

Selenium nanoparticles have a wide range application in industry, biomedical and environmental fields due to their unique physical, chemical and photoelectrical properties. This study was aimed to use aquatic bacteria in bioreduction of selenite oxyanioninto elemental nano-selenium.

Synthesized selenium nanoparticles were characterized by spectroscopic analysis and electromicrographs prepared by scanning electron microscopy (SEM). The efficacy of the antimicrobial activity of the synthesized selenium nanoparticles against some Gram-positive and Gram-negative human pathogenic bacteria was also investigated by the agar well diffusion test.

Sixteen selenite-resistant bacterial strains were isolated based on selective enrichment techniques in Tryptic Soy Agar (TSA) medium containing 5 mM selenite ion. Our results showed that Pseudomonas alcaligenes SR5 coastal seawater isolate can reduce selenite oxyanion into selenium nanoparticles. Furthermore, the results showed that extracellular selenium nanoparticles with an average size of 36 nm were formed in an optimum selenite concentration of 3 mM and an optimum initial biomass concentration of 15 g/l, following 96 h incubation at 25ᵒ C at (200 rpm under resting cell condition.

The current study is the first report on extracellular synthesis of selenium nanoparticles using P. alcaligenes. The produced bio-nanoparticles showed a growth inhibitory effect against four tested pathogenic bacterial strains.