A sulfamethazine (SM2) degrading strain, JD417, was isolated from sulfonamide-contaminated sludge using gradient acclimation. Optimal SM2 degradation conditions were pH 7, 36 °C, and 5 % inoculum, achieving a theoretical maximum degradation rate of 48 % at 50 ppm SM2. Cell growth followed the Haldane equation across different SM2 concentrations. Whole-genome sequencing of the strain revealed novel functional annotations, including a sulfonamide resistance gene () encoding dihydropteroate synthase, two flavin-dependent monooxygenase genes ( and ) crucial for SM2 degradation, and unique genomic islands related to metabolism, pathogenicity, and resistance. Comparative genomics analysis showed good collinearity and homology with other species exhibiting organics resistance or degradation capabilities. This study reveals the novel molecular resistance and degradation mechanisms and genetic evolution of an SM2-degrading strain, providing insights into the bioremediation of sulfonamide-contaminated environments.

中文翻译：

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一株新磺胺二甲嗪抗性基因及磺胺二甲嗪降解基因簇无色杆菌菌株的分离鉴定及全基因组分析

使用梯度驯化从磺酰胺污染的污泥中分离出磺胺二甲嗪 (SM2) 降解菌株 JD417。最佳 SM2 降解条件为 pH 7、36 °C 和 5% 接种量，在 50 ppm SM2 下实现 48% 的理论最大降解率。不同 SM2 浓度下的细胞生长遵循 Haldane 方程。该菌株的全基因组测序揭示了新的功能注释，包括编码二氢蝶酸合酶的磺酰胺抗性基因 ()、对 SM2 降解至关重要的两个黄素依赖性单加氧酶基因 (和)，以及与代谢、致病性和抗性相关的独特基因组岛。比较基因组学分析显示与其他表现出有机物抗性或降解能力的物种具有良好的共线性和同源性。这项研究揭示了 SM2 降解菌株的新型分子耐药性和降解机制以及遗传进化，为磺胺污染环境的生物修复提供了见解。