ABSTRACT The removal of fluoride is essential for water contaminated with fluoride before being utilized since the unsafe concentration of fluoride with respect to the permissible limits. In the present study, there are 61 bacterial strains belonging to fluoride tolerance were isolated from the contaminated soil of Dharmapuri District, Tamil Nadu, India and they were evaluated for different characterization. Among the strains isolated, the strain PN4 showed a high tolerance to fluoride ranging from 500 to 2500 ppm under different stress conditions. The strain PN4 was selected as a possible organism for the degradation and removal of fluoride in an aqueous medium. Based on the morphology, biochemical characteristics and the 16S rRNA sequencing, the bacterium PN4 was identified as Bacillus flexus. In batch mode studies, the glucose was showed the maximum removal of fluoride (86%) followed by beef extract (82%) and a significant level of defluoridation was observed at pH 7.0 and the temperature at 35°C. In the antibiotic-resistance pattern, the strain Bacillus flexus PN4 was shown sensitive to three different antibiotics. Intracellular accumulation of fluoride by the bacterial cell was characterized by SEM- EDAX, TEM and FTIR analysis. GRAPHICAL ABSTRACT

中文翻译：

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在最佳条件下通过弯曲芽孢杆菌（PN4）细胞内积累去除水介质中的氟化物

摘要 对于被氟化物污染的水，在使用前去除氟化物是必不可少的，因为氟化物的浓度相对于允许的限制是不安全的。在本研究中，从印度泰米尔纳德邦 Dharmapuri 区的污染土壤中分离出 61 株耐氟菌株，并对它们的不同特征进行了评估。在分离的菌株中，菌株 PN4 在不同应力条件下对氟化物显示出高耐受性，范围为 500 至 2500 ppm。菌株 PN4 被选为一种可能的生物体，用于在水性介质中降解和去除氟化物。基于形态学、生化特征和16S rRNA测序，该菌PN4被鉴定为弯曲芽孢杆菌(Bacillus flexus)。在批处理模式研究中，葡萄糖的氟化物去除率最高 (86%)，其次是牛肉提取物 (82%)，并且在 pH 7.0 和 35°C 的温度下观察到显着的除氟水平。在抗生素抗性模式中，弯曲芽孢杆菌 PN4 菌株对三种不同的抗生素敏感。通过 SEM-EDAX、TEM 和 FTIR 分析表征细菌细胞在细胞内积累的氟化物。图形概要