Strains Rhodococcus qingshengii djl-6 and Rhodococcus jialingiae djl-6-2 both harbour the typical carbendazim degradation pathway with the hydrolysis of carbendazim to 2-aminobenzimidazole (2-AB) as the initial step. However, the enzymes involved in this process are still unknown. In this study, the previous reported carbendazim hydrolase MheI was found in strain djl-6, but not in strain djl-6-2, then another carbendazim hydrolase CbmA was obtained by a four-step purification strategy from strain djl-6-2. CbmA was classified as a member of the amidase signature superfamily with conserved catalytic site residues Ser157, Ser181, and Lys82, while MheI was classified as a member of the Abhydrolase superfamily with conserved catalytic site residues Ser77 and His224. The catalytic efficiency (k_cat/K_m) of MheI (24.0–27.9 μM⁻¹ min⁻¹) was 200 times more than that of CbmA (0.032–0.21 μM⁻¹ min⁻¹). The mheI gene (plasmid encoded) was highly conserved (>99% identity) in the strains from different bacterial genera and its plasmid encoded flanked by mobile genetic elements. The cmbA gene was highly conserved only in strains of the genus Rhodococcus and it was chromosomally encoded. Overall, the function, diversity, and distribution of carbendazim hydrolases MheI and CbmA will provide insights into the microbial degradation of carbendazim.

中文翻译：

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多菌灵水解酶 MheI 和 CbmA 的功能分析、多样性和分布，负责多菌灵降解的初始步骤

菌株青生红球菌djl-6 和嘉陵红球菌djl-6-2 都具有典型的多菌灵降解途径，其中多菌灵水解为 2-氨基苯并咪唑 (2-AB) 作为初始步骤。然而，参与这个过程的酶仍然未知。在本研究中，先前报道的多菌灵水解酶MheI在菌株djl-6中发现，但在菌株djl-6-2中未发现，然后通过四步纯化策略从菌株djl-6-2中获得另一种多菌灵水解酶CbmA。CbmA 被归类为具有保守催化位点残基 Ser157、Ser181 和 Lys82 的酰胺酶特征超家族的成员，而 MheI 被归类为具有保守催化位点残基 Ser77 和 His224 的 Abhydrolase 超家族的成员。MheI的催化效率( k _cat / K _m ) (24.0–27.9 μM)^-1  min ^{-1 ) 是 CbmA (0.032–0.21 μM -1}  min ^-1 )的 200 倍。mheI基因（质粒编码）在来自不同细菌属的菌株中高度保守（>99% 同一性），其质粒编码的质粒两侧有可移动的遗传元件。cmbA基因仅在红球菌属菌株中高度保守，并且它是由染色体编码的。总体而言，多菌灵水解酶 MheI 和 CbmA 的功能、多样性和分布将为多菌灵的微生物降解提供见解。