Biogenic synthesis of selenium nanoparticles by moderate halophilic bacteria and evaluation of its anti-bacterial and anti-biofilm activity

Abstract

Abstract In the present investigation, the selenium nanoparticles (SeNPs) were biosynthesized from moderate halophilic bacteria (that can grow optimally at 3–15% NaCl) isolated from Pichavaram mangrove sediments. The bacterial strain S8 was found to be efficient for SeNPs synthesis and hence identified by 16s r RNA sequencing as Shewanella sp. In UV- spectral analysis the SeNPs displayed peak at 320 nm due to surface plasmon resonance (SPR). The cell free extract of Shewanella sp. and SeNPs clearly indicate that the various functional groups in the cell free extract were mainly involved in synthesis and stabilisation of SeNPs. The SeNPs had a spherical form and a 20 nm size, according to the FESEM analysis. The EDX show the distinctive peaks of selenium at 1.37, 11.22.12.49 Kev. In agar well diffusion method the SeNPs shows inhibitory activity against all the test pathogens with the highest activity was noted against P. aeruginosa with zone of inhibition of 23 ± 0.5mm. In the micro broth dilution method, lowest minimal inhibitory concentration (MIC) value was recorded against P. aeruginosa with 8µg/200µl and minimal bactericidal concentration (MBC) of 16 µg/100µl. SeNPs at concentrations of more than 50 µg/ml were found to inhibit P. aeruginosa biofilm by 85% in the anti-biofilm study.