Eco-friendly bioremediation of pollutants from contaminated sewage wastewater using special reference bacterial strain of Bacillus cereus SDN1 and their genotoxicological assessment in Allium cepa

The present study aimed to assess the Bacillus cereus SDN1 native bacterium's ability to clean up contaminated or polluted water. The isolated bacterium was identified by its morphological and biochemical characteristics, which were then confirmed at the genus level. Furthermore, the isolated B. cereus (NCBI accession No: MW828583) was identified genomically by PCR amplifying 16 s rDNA using a universal primer. The phylogenetic analysis of the rDNA sequence was analyzed to determine the taxonomic and evolutionary profile of the isolate of the previously identified Bacillus sp. Besides, B. cereus and the bacterial consortium were treated using sewage wastewater. After 15 days of treatment, the following pollutants or chemicals were reduced: total hardness particles removal varied from 63.33 % to 67.55 %, calcium removal varied from 90 % to 93.33 %, and total nitrate decreased range from 37.77 % to 22.22 %, respectively. Electrical conductivity ranged from 1809 mS/cm to 2500 mS/cm, and pH values ranged from 6.5 to 8.95. The outcome of in-situ remediation results suggested that B. cereus has a noticeable remediation efficiency to the suspended particles. A root tip test was also used to investigate the genotoxicity of treated and untreated sewage-contaminated waters on onion (Allium cepa) root cells. The highest chromosomal aberrations and mitotic inhibition were found in roots exposed to contaminated sewage water, and their results displayed chromosome abnormalities, including disorganized, sticky chain, disturbed metaphase, chromosomal displacement in anaphase, abnormal telophase, spindle disturbances, and binucleate cells observed in A. cepa exposed to untreated contaminated water. The study can thus be applied as a biomarker to detect the genotoxic impacts of sewage water pollution on biota. Furthermore, based on an identified bacterial consortium, this work offers a low-cost and eco-favorable method for treating household effluents.

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.