A study on fluoride bioremediation via a novel bacterium Bacillus megaterium (JF273850) isolated from agricultural soil

Micro-organisms often exhibit tolerance to a wide range of pollutants for their existence in different adverse environments. Fluoride is one of the potential geogenic contaminants setting up a great ecological concern in the world as well as in India. It is a protoplasmic toxin and minimal amount of it can initiate several biochemical changes in micro-organisms. The objectives of the present investigation were to isolate fluoride-resistant bacteria from the contaminated agricultural soil matrix of fluoride-prone area and to evaluate the fluoride contamination status of soil and groundwater. The fluoride level was found to be in the range of 1.98-2.32 mg/kg and 0.17-5.33 mg/L in the soil and groundwater, respectively. A new fluoride-resistant bacterial strain (NM27) was isolated from the agricultural soil. The 16S rRNA gene sequencing, phylogenetic analysis, and phenotypic characterisation revealed that the bacterial isolate is very similar to Bacillus megaterium (JF273850). The G+C and A+T content of the 16S rDNA was found to be 53.34 and 46.66 mol%, respectively. The isolated strain showed positive tests for catalase, lipase, urease, protease, oxidase, and H2S production along with sensitivity towards the recommended doses of various antibiotics. This bacterial isolate can survive both in high level of fluoride (1500 mg/L) and sodium chloride (35% w/v) solution and in a medium having wide pH range (4-12). The 16S rRNA gene sequence of the bacterial isolate, NM27 has been deposited in the NCBI Gene bank and was assigned the accession number (JF273850). Fluoride bioaccumulation study suggested that this particular strain (NM27) can reduce the fluoride concentration in the culture medium up to 70%. Therefore, it can be concluded that bacterial strain Bacillus megaterium could be used for bioremediation of fluoride.

Automated summary

This study isolated a new fluoride-resistant bacterial strain (NM27) from fluoride-contaminated agricultural soil and evaluated the fluoride contamination status of soil and groundwater. The isolated strain, identified as Bacillus megaterium, exhibited tolerance to high levels of fluoride, sodium chloride, and a wide pH range. It also demonstrated the ability to reduce fluoride concentration in the culture medium by up to 70%.