[P004] Poster

1:00 PM - 1:50 PM JST(4:00 AM - 4:50 AM UTC)

[P02-230] Generation of Transgenic Arabidopsis thaliana Expressing Bacterial Genes for Organochlorine Insecticide Degradation and Their Application in Soil

○Hana Kojima¹, Wenhao Deng, Yoshinobu Takada¹, Kohei Kishida¹, Yoshiyuki Otsubo¹, Masao Watanabe¹, Yuji Nagata¹ (1. Graduate School of Tohoku University (Japan))

Keywords:

Phytoremediation

The organochlorine insecticide γ-hexachlorocyclohexane (γ-HCH) remains an important environmental pollutant, even though its use is now essentially prohibited, and it is designated as a persistent organic pollutant (POP) together with α-HCH and β-HCH. The γ-HCH–degrading bacterium Sphingobium japonicum strain UT26 has been isolated, and its entire γ-HCH degradation pathway has been elucidated. However, due to limitations such as poor survival in soil, direct application of this strain for bioremediation is difficult. Therefore, we aim to generate transgenic plants expressing γ-HCH degradation genes derived from this strain and apply them to the remediation of contaminated soils. We introduced the gene, optimized for expression in plants, encoding LinA, the initial enzyme in the γ-HCH degradation pathway, into Arabidopsis thaliana and obtained a transgenic line (A5-3) with stable LinA expression (Deng et al., BMC Biotechnology, 24, 42, 2024). The A5-3 line absorbed and degraded γ-HCH in liquid medium, indicating the high potential of LinA-expressing transgenic plants for the phytoremediation of environmental γ-HCH. However, when the A5-3 line was cultivated in soil artificially contaminated with γ-HCH, no significant difference was observed in the residual γ-HCH levels in the soil, although the γ-HCH content in plant tissues was markedly lower in the A5-3 line than in the wild type (WT). Therefore, we re-examined both the method for preparing contaminated soil and the procedure for extracting γ-HCH from soil. As a result, we found that, rather than mixing Celite adsorbed with γ-HCH into the soil, directly adding γ-HCH to the soil and performing the extraction process using the nonionic surfactant Tween 20 at least twice enabled detection of γ-HCH at levels corresponding to the amount initially added. Using this improved method, we found that the γ-HCH level in soil cultivated with A5-3 was significantly lower than that in soil cultivated with the WT, suggesting that the A5-3 line absorbs and degrades γ-HCH in artificially contaminated soil. In addition, we are developing transgenic A. thaliana expressing LinB_MI, a variant of LinB with strong β-HCH–degrading activity, as well as plants co-expressing both LinA and LinB.