Isolation of Microorganisms From Soil Contaminated With Dioxins

This is the authors' abstract. We don't add key points for this paper.

Soil pollution with dioxins is a serious environmental problem, especially in Vietnam, where the military use of herbicides by the US Army has led to long-term contamination. Existing physicochemical remediation methods are ineffective for large areas, which makes it urgent to develop biological approaches, particularly phytoremediation using microbial destructors. The aim of this study was to isolate bacterial strains capable of dioxin degradation from contaminated soils at Bien Hoa Airfield (Vietnam) and evaluate their potential for phytoremediation. Thirty-seven morphologically distinct isolates were isolated using selection methods on a medium containing 2,3,7,8-tetrachlorodibenzo-p-dioxin. Taxonomic analysis using the 16S rRNA gene revealed a predominance of gram-positive spore-forming bacteria of the genera Bacillus, Priestia, and Niallia (approximately 41%) and actinomycetes of the genus Rhodococcus (approximately 14%). Box-PCR genotyping confirmed the genetic diversity of the collection. Non-pathogenic strains were selected, including active tomato root colonizers (Pseudomonas putida D01L2B02, Bacillus amyloliquefaciens D01L2B03, Bacillus tropicus PIB0314/5), possessing a complex of enzymatic activities (protease, amylase, lipase, phytase) and the ability to fix nitrogen. B. tropicus PIB0314/5 demonstrated a statistically significant phytostimulating effect on tomatoes. The results indicate that the isolated native bacterial strains are promising candidates for the development of microbial preparations and the creation of effective phytoremediation systems for soils contaminated with dioxins.