Xanthobacter dioxanivorans sp. nov., a 1,4-dioxane-degrading bacterium

Current research on microbial degradation of pollutants has identified several species capable of breaking down toxic compounds. However, specific bacteria that target 1,4-dioxane remain underexplored. Prior studies have established that certain bacteria can degrade this compound, but the full range of species involved is not yet understood. The discovery of new bacterial species with unique metabolic capabilities can expand bioremediation options. Existing knowledge suggests that 1,4-dioxane is a persistent environmental contaminant. This gap motivated investigations into isolating and characterizing novel strains. No prior work had resolved the taxonomic placement of a newly identified 1,4-dioxane-degrading bacterium. The lack of detailed genomic and phenotypic data for such organisms limits their application in environmental cleanup efforts. This paper addresses that uncertainty by introducing a newly identified strain and its classification.

The aim of the study was to identify and classify a novel bacterium capable of degrading 1,4-dioxane. The researchers focused on isolating and characterizing a strain from a wastewater treatment plant. They aimed to determine the strain’s phylogenetic, phenotypic, and genomic traits. The motivation for this work was to expand the known microbial tools for bioremediation. The study sought to confirm whether the strain belongs to a new species within the genus Xanthobacter. The researchers also aimed to compare the strain with known species using DNA-DNA hybridization and sequence analysis. This work contributes to the understanding of microbial diversity in biodegradation. The findings may support future applications in environmental cleanup efforts.

The researchers isolated strain YN2T from activated sludge collected in a wastewater treatment plant. They performed Gram staining and observed the morphological characteristics of the cells. The strain’s growth conditions were tested across a range of temperatures, pH levels, and salt concentrations. Phylogenetic analysis was conducted using 16S rRNA gene sequencing. The strain’s respiratory quinones and fatty acid composition were analyzed chemotaxonomically. DNA-DNA hybridization was performed to compare the strain with related species. Average nucleotide identity and amino acid identity were calculated using genome sequences. The strain’s ability to fix nitrogen and grow chemolithoautotrophically was also assessed.

Strain YN2T was found to be a Gram-negative, aerobic, and motile rod-shaped bacterium. It exhibited optimal growth at 30 °C and pH 7.0 with 0.1 % NaCl. The strain could degrade 1,4-dioxane and fix nitrogen in the absence of ammonium or nitrate. Phylogenetic analysis placed it within the genus Xanthobacter, with highest 16S rRNA gene identity to Xanthobacter autotrophicus (98.6 %). The major respiratory quinone was ubiquinone-10. Fatty acid analysis showed C16:0, C19:0 cyclo ω8c, and C18:1 ω7c as dominant components. DNA G+C content was 67.95 mol%. DNA-DNA hybridization values with related species were below 32 %. These findings indicate that YN2T represents a novel species.

The authors propose that strain YN2T represents a new species within the genus Xanthobacter. This conclusion is based on phylogenetic, phenotypic, and genomic data. The strain’s unique ability to degrade 1,4-dioxane and fix nitrogen supports its classification as a novel species. The low DNA-DNA hybridization values with related species confirm its distinctness. The study’s findings align with the criteria for species delineation in bacterial taxonomy. The proposed name for the new species is Xanthobacter dioxanivorans. The authors suggest that this strain may have potential applications in bioremediation. The study contributes to the growing understanding of microbial diversity in environmental contexts.