Phthalate esters have raised public concerns owing to their effects on the environment and human health. We identified a novel phthalate-degrading hydrolase, EstJ6, from a metagenomic library using function-driven screening. Phylogenetic analysis indicated that EstJ6 is a member of family IV esterases. EstJ6 hydrolyzed various dialkyl and monoalkyl phthalate esters, and exhibited high hydrolytic activity (128 U/mg) toward dibutyl phthalate at 40 °C and pH 7.5. EstJ6 hydrolyzed not only common phthalate esters with simple side chains but also diethylhexyl phthalate and monoethylhexyl phthalate, which have complex and long side chains. Site-directed mutagenesis indicated that the catalytic triad residues of EstJ6 consists of Ser146, Glu240, and His270. EstJ6 is therefore a promising biodegradation enzyme, and our study illustrates the advantages of a metagenomic approach in identifying enzyme-coding genes for agricultural, food, and biotechnological applications.

中文翻译：

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从土壤宏基因组库中鉴定和表征新型降解邻苯二甲酸酯的水解酶。

邻苯二甲酸酯由于其对环境和人类健康的影响而引起了公众的关注。我们使用功能驱动的筛选从宏基因组库中鉴定了一种新型的邻苯二甲酸酯降解水解酶EstJ6。系统发育分析表明，EstJ6是家族IV酯酶的成员。EstJ6水解了各种邻苯二甲酸二烷基酯和邻苯二甲酸单烷基酯，并在40°C和pH 7.5下表现出对邻苯二甲酸二丁酯的高水解活性（128 U / mg）。EstJ6不仅水解具有简单侧链的普通邻苯二甲酸酯，而且还水解具有复杂且长侧链的邻苯二甲酸二乙基己酯和邻苯二甲酸单乙基己酯。定点诱变表明EstJ6的催化三联体残基由Ser146，G​​lu240和His270组成。因此，EstJ6是一种很有前途的生物降解酶，