N-acylhomoserine lactones (AHLs) are auto-inducers found in gram-negative bacteria and are ubiquitous in common plant pathogenic bacteria. N-acylhomoserine lactonase degrades the lactone ring of AHLs to achieve quorum quenching of phytopathogenic virulence genes. In this study, a novel AHL lactonase gene KaAhl was successfully cloned and identified from Kushneria avicenniae strain DSM 23439. KaAhl is encoded a 261-residue polypeptide belonging to the metallo-β-lactamase superfamily. The recombinant enzyme displayed maximum hydrolysis activity of 0.64 U/mg toward N-(3-oxooctanoyl)-L-homoserine lactone substrate at 30^oC and pH 8.0. Besides, it had moderate thermal stability but exhibited a high salt tolerance showing approximate 50% relative activity in the presence of 35% concentrations of NaCl. Furthermore, the KaAhl was significantly promoted by Mn²⁺ and Ni²⁺, which enhanced the lactonase activity to approximate 100% extent. In addition, it was observed that recombinant Escherichia coli BL21-pET28a-KaAhl producing KaAhl proteins could effectively inhibit the plant pathogenicity of Erwinia carotovora for 72 h, which might have great potential for controlling gram-negative pathogenic bacteria.

N-酰基高丝氨酸内酯（AHLs）是革兰氏阴性菌中的自诱导剂，在常见的植物病原菌中普遍存在。N-酰基高丝氨酸内酯酶降解 AHLs 的内酯环以实现植物病原毒力基因的群体淬灭。在这项研究中，成功克隆和鉴定了一种新的AHL内酯酶基因KaAhl，该基因是从A. Kushneria avicenniae菌株DSM 23439中鉴定的。KaAhl被编码为261个残基的多肽，属于金属β-内酰胺酶超家族。重组酶在 30 ^{o 时}对 N-(3-氧代辛酰基)-L-高丝氨酸内酯底物的最大水解活性为 0.64 U/mgC和pH 8.0。此外，它具有中等的热稳定性，但表现出高耐盐性，在 35% 浓度的 NaCl 存在下显示大约 50% 的相对活性。此外，Mn ²⁺和Ni ²⁺显着促进了KaAhl ，从而将内酯酶活性提高了约100％。此外，有人指出，重组大肠杆菌BL21-的pET28a KaAhl产生KaAhl蛋白能有效抑制的植物致病性软腐病72小时，这可能会具有用于控制革兰氏阴性致病细菌的巨大潜力。