Metabolic gene analysis of newly isolated Pseudochrobactrum sp. BJQ-1 and BJQ-2 reveals global dissemination of the chlorothalonil hydrolytic dehalogenase chd gene
- 1College of Rural Revitalization, Jiangsu Open University
- 2Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University
- 3State Key Laboratory of Microbial Technology, School of Food Science and Pharmaceutical Engineering, Nanjing Normal University
Abstract
Chlorothalonil (TPN; 2,4,5,6-tetrachloroisophthalonitrile) is a globally used, persistent chlorinated fungicide. Its bacterial detoxification is driven mainly by the hydrolytic dehalogenase Chd. Although the chd gene and its association with mobile genetic elements have been reported, the extent to which identical chd modules have spread across distinct hosts on a global scale remains unclear. Here we isolated two chlorothalonil-degrading strains, BJQ-1 and BJQ-2, from geographically distinct sites. Both were identified as Pseudochrobactrum spp. by 16S rRNA phylogeny. Shotgun cloning and sequence comparison revealed that both strains harbor a chd ORF essentially identical (≥99.7% nucleotide identity) to those of Pseudomonas sp. CTN series, Paracoccus sp. XF-3 and Ochrobactrum lupini TP-D1. The same chd gene is embedded in three distinct mobile-element configurations, an IS 21 -like composite transposon in CTN series, an IS 6 -family transposase TnpA plus Pin recombinase in BJQ-1, and a λ Rac-like invertase in BJQ-2, a pattern incompatible with vertical inheritance. Upstream spacer analysis showed that a conserved IS 21 -like fusion promoter, composed of an IRR-borne −35 box fused to the native −10 element of chd gene, and the 179-bp istB–chd intergenic spacer (100% identical between the BJQ isolates and the CTN series) are preserved. Mining of the Prokaryotic Genome dataset retrieved chd -like sequences from diverse prokaryotic genomes spanning soil, aquatic and plant-associated habitats, confirming a broad phylogeography of the cassette. The recovery of an identical, transposon-associated chd module from two distantly sampled Pseudochrobactrum strains, together with its global genomic distribution, indicates that the chd detoxification cassette has disseminated worldwide, providing a general mechanism for the rapid recruitment of TPN biodegradation capacity in microbial communities.
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BibTeX
@article{ke2026metabolic,
title = {{Metabolic gene analysis of newly isolated Pseudochrobactrum sp. BJQ-1 and BJQ-2 reveals global dissemination of the chlorothalonil hydrolytic dehalogenase chd gene}},
author = {Zhuang Ke and Qi Wu and Min Gao and Qilin Wang and Lin Wang and Cansheng Yuan},
journal = {Frontiers in Microbiology},
year = {2026},
month = oct,
doi = {10.3389/fmicb.2026.1965943},
url = {https://www.frontiersin.org/articles/10.3389/fmicb.2026.1965943/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Metabolic gene analysis of newly isolated Pseudochrobactrum sp. BJQ-1 and BJQ-2 reveals global dissemination of the chlorothalonil hydrolytic dehalogenase chd gene
AU - Zhuang Ke
AU - Qi Wu
AU - Min Gao
AU - Qilin Wang
AU - Lin Wang
AU - Cansheng Yuan
PY - 2026
DA - 2026/10/06
JO - Frontiers in Microbiology
DO - 10.3389/fmicb.2026.1965943
UR - https://www.frontiersin.org/articles/10.3389/fmicb.2026.1965943/full
AB - Chlorothalonil (TPN; 2,4,5,6-tetrachloroisophthalonitrile) is a globally used, persistent chlorinated fungicide. Its bacterial detoxification is driven mainly by the hydrolytic dehalogenase Chd. Although the chd gene and its association with mobile genetic elements have been reported, the extent to which identical chd modules have spread across distinct hosts on a global scale remains unclear. Here we isolated two chlorothalonil-degrading strains, BJQ-1 and BJQ-2, from geographically distinct sites. Both were identified as Pseudochrobactrum spp. by 16S rRNA phylogeny. Shotgun cloning and sequence comparison revealed that both strains harbor a chd ORF essentially identical (≥99.7% nucleotide identity) to those of Pseudomonas sp. CTN series, Paracoccus sp. XF-3 and Ochrobactrum lupini TP-D1. The same chd gene is embedded in three distinct mobile-element configurations, an IS 21 -like composite transposon in CTN series, an IS 6 -family transposase TnpA plus Pin recombinase in BJQ-1, and a λ Rac-like invertase in BJQ-2, a pattern incompatible with vertical inheritance. Upstream spacer analysis showed that a conserved IS 21 -like fusion promoter, composed of an IRR-borne −35 box fused to the native −10 element of chd gene, and the 179-bp istB–chd intergenic spacer (100% identical between the BJQ isolates and the CTN series) are preserved. Mining of the Prokaryotic Genome dataset retrieved chd -like sequences from diverse prokaryotic genomes spanning soil, aquatic and plant-associated habitats, confirming a broad phylogeography of the cassette. The recovery of an identical, transposon-associated chd module from two distantly sampled Pseudochrobactrum strains, together with its global genomic distribution, indicates that the chd detoxification cassette has disseminated worldwide, providing a general mechanism for the rapid recruitment of TPN biodegradation capacity in microbial communities.
SN - 1664-302X
ER -