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

Abstract

To investigate the ability of Haloferax alexandrinus GUSF-1 (KF796625) to biosynthesize non-toxic elemental selenium (Se0 ) and check their capacity in in vitro crystal structure modulation of calcium oxalate, which are implicated in the development of renal calculi. Haloferax alexandrinus GUSF-1 (KF796625) during growth in the presence of 5mmolL-1 of selenite formed insoluble brick-red particles. Se0 formed was monitored spectrophotometrically using a combination of two assays; the ascorbic acid reduction and sodium sulphide solubilization assay. After 168h of growth, 2.89mmolL-1 of Se0 was formed from 4.9mmolL-1 of selenite. Absorption bands at 1.5, 11.2 and 12.5keV in EDX spectroscopy confirmed that the brick-red particulate matter was Se0 . Furthermore, these selenium nanoparticles (SeNPs) were pentagonal in shape in transmission electron microscopy imaging. The peak positions in X-ray diffractogram at 2θ values of 23.40°, 29.66°, 41.26°, 43.68°, 45.24°, 51.62°, 55.93° and 61.47° and the relative intensities further confirmed the formation of Se0 . In vitro addition of 50 and 100µgml-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± 0.2 µm2 ) to smaller rectangular-shaped crystals (average area of 0.54± 0.2 µm2 ) and spherical-shaped crystals (average area 0.13± 0.005 µm2 ). Haloferax alexandrinus GUSF-1 (KF796625) transformed selenite to Se0 pentagonal nanoforms that modulated in vitro the formation of crystal shape and size of calcium oxalate. There are no reports on conversion of selenite to Se0 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.