Conversion of selenite by Haloferax alexandrinus GUSF-1 (KF796625) to pentagonal selenium nanoforms which in vitro modulates the formation of calcium oxalate crystals

Abstract

Aim: To investigate the ability of Haloferax alexandrinus GUSF-1 (KF796625) to biosynthesize non-toxic elemental selenium (Se sup(0)) and check their capacity in in vitro crystal structure modulation of calcium oxalate, which are implicated in the development of renal calculi. Methods and Results: Haloferax alexandrinus GUSF-1 (KF796625) during growth in the presence of 5 mmol L sup(-1) of selenite formed insoluble brick-red particles. Se sup(0) formed was monitored spectrophotometrically using a combination of two assays; the ascorbic acid reduction and sodium sulphide solubilization assay. After 168 h of growth, 2.89 mmol L sup(-1) of Se sup(0) was formed from 4.9 mmol L sup(-1) of selenite. Absorption bands at 1.5, 11.2 and 12.5 keV in EDX spectroscopy confirmed that the brick-red particulate matter was Se sup(0). Furthermore, these selenium nanoparticles (SeNPs) were pentagonal in shape in transmission electron microscopy imaging. The peak positions in X-ray diffractogram at 2 Theta values of 23.40 degree, 29.66 degree, 41.26 degree, 43.68 degree, 45.24 degree, 51.62 degree, 55.93 degree and 61.47 degree and the relative intensities further confirmed the formation of Se sup(0). In vitro addition of 50 and 100 Mu g ml sup(-1) of these SeNPs to the mixture of sodium chloride, calcium chloride and sodium oxalate affected and modulated the shape and size of rectangular-shaped calcium oxalate crystals (average area of 1.23 plus or minus 0.2 Mu m sup(2)) to smaller rectangular-shaped crystals (average area of 0.54 plus or minus 0.2 Mu m sup(2)) and spherical-shaped crystals (average area 0.13 plus or minus 0.005 Mu m sup(2)). Conclusion: Haloferax alexandrinus GUSF-1 (KF796625) transformed selenite to Se sup(0) pentagonal nanoforms that modulated in vitro the formation of crystal shape and size of calcium oxalate. Significance and Impact of Study: There are no reports on conversion of selenite to Se sup(0) among the Haloferax genera, and this study involving the formation of pentagonal SeNPs with capacity to modulate the formation of calcium oxalate crystals in haloarchaea is recorded as the first report and of significance in pharmaceutical research related to formulations abetting urinary calculi.