# Genomic Insights into Dechloromonas sp. TW-R-39-2: A Dual-Function Bacterium for Heavy Metal Sequestration and Chlorinated Organic Degradation

## TL;DR

A new Dechloromonas bacterium can both remove heavy metals and break down toxic organic pollutants, making it useful for cleaning contaminated water.

## Contribution

Discovery of a novel Dechloromonas strain with dual capabilities for heavy metal sequestration and chlorinated compound degradation.

## Key findings

- Strain TW-R-39-2 showed 78% cadmium and 75% zinc adsorption efficiency.
- The bacterium degraded 83.6% trichloroethylene and 81% chlorophenol in 7 days.
- Chloride ion release confirmed complete dechlorination of pollutants.

## Abstract

Environmental contamination caused by various types of heavy metals and chlorinated organic compounds poses a significant threat to global ecosystems. While bioremediation offers a sustainable solution, identifying microbial strains that possess the metabolic versatility to withstand metal toxicity and degrade persistent organic pollutants remains a major challenge. In this study, we characterized strain TW-R-39-2, a novel bacterium isolated from a wastewater treatment plant. Phylogenomic analysis based on complete genome sequencing revealed that strain TW-R-39-2 represents a novel species within the genus Dechloromonas, showing Average Nucleotide Identity (ANI) and digital DNA–DNA hybridization (dDDH) values of 80.17% and 23.4%, respectively, with its closest relative, Dechloromonas denitrificans. Genomic insights revealed a 3.46 Mb circular chromosome containing a diverse array of genes associated with heavy metal resistance (e.g., predicted czc and cadA clusters) and chlorinated compound degradation (e.g., dehalogenases). Phenotypic assays validated these genomic predictions, demonstrating the strain’s dual functionality: it exhibited high adsorption efficiencies for cadmium (Cd2+, 78.0%) and zinc (Zn2+, 75.1%), alongside significant degradative capacity for trichloroethylene (TCE, 83.6%) and chlorophenol (81.0%) within a 7-day incubation period, corresponding to the strain’s active growth and early stationary phases. The stoichiometric release of chloride ions confirmed the complete dechlorination of the organic pollutants. These findings demonstrate that strain TW-R-39-2 possesses versatile capacities for both the sequestration of toxic metals and the biodegradation of persistent organic compounds. This study highlights the potential of strain TW-R-39-2 as a promising candidate for the efficient bioremediation of diverse industrial wastewaters.