Characterization of a novel Fluoride resistant bacterial isolate and its capability of Fluoride bioremediation

A Gram positive rod shaped bacterium designated as isolate H1 with Fluoride resistance up to 4 g/L sodium fluoride (NaF) in LB (Luria-Bertani) agar was isolated from a ground water sample of Narketpally area, Nalgonda district, Telangana, India. The colonies of isolate H1 were off white in color. Growth patterns of isolate H1 were observed at two different concentrations, 100 and 250 ppm, of NaF and also without NaF in the medium. In cases where NaF was present in the media, the lag phases of the growth curves were extended when compared to the absence of NaF. Optimum pH required for the organism's growth was 8. Isolate H1 required a temperature of 37 °C with 150 rpm and 2% NaCl for its optimal growth in the medium without NaF. Meanwhile, isolate H1 could thrive in a diverse pH range, i.e., pH 5-10, and at an NaCl concentration of up to 11% in the medium with NaF. Based on morphological, biochemical and molecular characterization, isolate H1 was identified as belonging to the genus Bacillus. It showed 98.47% 16S rDNA gene sequence similarity with Bacillus australimaris NH71_1^T. Isolate H1 showed high fluoride removals of 22.5% and 38.2% with 100 and 250 mg/L of NaF in the LB broth when incubated at pH 8 and a temperature of 37 °C with 150 rpm for 3 day. Hence, this organism could be a promising isolate to apply for defluoridation of ground water in fluoride contaminthe ated areas.