Bioaccumulation of fluoride from aqueous system and genotoxicity study on Allium cepa using Bacillus licheniformis

Removal of fluoride (F^-) was performed using a novel bacterium isolated from F^- contaminated soil collected from Pappireddipatti block of Dharmapuri District in Tamil Nadu, India. Impact of changing variables for the removal of F^- from synthetic medium at different concentrations of carbon and nitrogen sources (0.5, 1.0 and 1.5 g) was studied with bio inoculants of the bacterial strain (PPR8). The effects of different environmental parameters viz., pH (5.0-9.0) and temperature (25-45 °C) on the biosorption of F^- biosorption were also evaluated. The strain PPR8 was identified as Bacillus licheniformis through 16S rRNA sequencing and phylogenetic analysis. Bioaccumulation of F^- in the bacterial cells was confirmed by FTIR, SEM and TEM-EDAX and almost 97% of F^- removal was established. To test the potential applicability of the bacterium, the bioreactor study was carried out with F^- contaminated groundwater collected from the contaminated area. Furthermore, the treated and untreated F^- contaminated waters were used to evaluate the genotoxicity on the root cells of onion (Allium cepa) by root tip assay. The experimental results proved that the significant removal of F^- by Bacillus licheniformis PPR8 (KX646393) and it could be used as a potential adsorbent in removing F^- from contaminated ground waters.