Bacterial distribution in long-term dioxin-contaminated soil in Vietnam and novel dioxin degrading bacteria isolated from Phu Cat airbase

ABSTRACT

Herbicide-/dioxin-contaminated contamination in Vietnam is an environmental issue nowadays, despite Agent Orange being sprayed a long time ago. High levels of dioxin in military airbases cause hot spots of dioxin contamination sites in which potential biological source of microorganisms has developed. Understanding microorganism structure in contaminated soil is crucial for the bioremediation of the sites. Illumina Miseq platform was applied to sequence V3-V4 amplicons of long-term contaminated communities to evaluate the bacterial distribution. Contaminated soil from different regions Bien Hoa and Phu Cat showed a low level of connectedness; the species richness of Bien Hoa was much higher than that of Phu Cat. However, they shared similarities in the most abundant bacterial phyla: Actinobacteriota, Chloroflexi, Proteobacteria, Acidobacteriota, and Planctomycetota. Several xenobiotic-degrading genera were found, such as Terrabacter, Nocardioides, and Streptomyces of Actinobacteriota; Bacillus, Paenibacillus, and Clostridium of Firmicutes; Burkholderia, Sphingomonas, Pseudomonas and Klebsiella of Proteobacteria. Seven bacterial isolates grew on dioxin-containing medium belonging to Firmicutes, they were classified in order Bacillales, in which two strains belong to Paenibacillaceae, and the rests are in Bacillaceae. Two isolates removed more than 80% of total toxicity (mainly 2,3,7,8-Tetrachlorodibenzo-p-dioxin); strain PC5 is the first dioxin-degrading bacterium recognized in the genus Neobacillus.

KEYWORDS:

• Dioxin
• contaminated soil
• 2,3,7,8-tetrachlorodibenzo-p-dioxin; bacterial distribution; dioxin degradation

Data availability statement

The data that support the findings of this study are openly available in Sequence Read Archive (SRA), National Center for Biotechnology Information at https://www.ncbi.nlm.nih.gov/bioproject/?term=PRJNA900620, reference number Bioproject number PRJNA900620.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15320383.2023.2195502.

Additional information

Funding

This work was supported by the Vietnam Ministry of Defence under Grant of project: “Research the manufacturing detection kits for quick assessment of toxic chemicals/dioxins in the environment and soil remediation technology for toxic chemicals/dioxins by combining biological products with nanomaterials”.