Detalle de: Genomic Analysis, Bioremediation Potential, and Toxicity Removal Efficiency of Metal-Resistant Strains Isolated from Tannery Effluents in Southern Tunisia

The discharge of tannery effluents poses an environmental challenge due to the harsh chemicals used in leather processing. Bacterial strains isolated from tannery effluent could be used for bioremediation purposes, however, lack of genomic analyses hinders exploring more effective bioremediation pathways. This study analyzes whole genome sequences and bioremediation potential of seven Enterococcus faecium strains and two Bacillus licheniformis strains isolated from the effluents of the Southern Tunisia tannery (ESTT), possessing novel genomic attributes. They differed by their heavy metal reducing capacity, although the genetic differences between the strains were not explicitly related to previously known bioremediation pathways. ESTT treated with either a combination of seven E. faecium strains and two B. licheniformis strains, or a mixture of all nine strains, showed no toxicity to plant seeds and blood cell. The combination of the nine strains resulted in a 1.85±0.81x heavy metal reduction compared to separate species mixtures and 3.94±1.99x compared to ESTT. Furthermore, they reduced chemical oxygen demand (COD) by 3.9x, chlorine (Cl) by 3.3x, biochemical oxygen demand (BOD5) by 2.16x, and total organic carbon (TOC) by 1.3x compared to ESTT. In conclusion, the utilization of strain mixtures for heavy metal reduction holds promise in meeting international environmental standards.