State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Heifei 230036, China.
School of Tea and Food Science Technology, Anhui Agricultural University, Heifei 230036, China.
J Hazard Mater. 2024 Jul 15;473:134716. doi: 10.1016/j.jhazmat.2024.134716. Epub 2024 May 23.
Ochratoxin A (OTA) is a toxic secondary metabolite that widely contaminates agro-products and poses a significant dietary risk to human health. Previously, a carboxypeptidase CP4 was characterized for OTA degradation in Lysobacter sp. CW239, but the degradation activity was much lower than its host strain CW239. In this study, an amidohydrolase ADH2 was screened for OTA hydrolysis in this strain. The result showed that 50 μg/L OTA was completely degraded by 1.0 μg/mL rADH2 within 5 min, indicating ultra-efficient activity. Meanwhile, the two hydrolases (i.e., CP4 and ADH2) in the strain CW239 showed the same degradation manner, which transformed the OTA to ochratoxin α (OTα) and l-β-phenylalanine. Gene mutants (Δcp4, Δadh2 and Δcp4-adh2) testing result showed that OTA was co-degraded by carboxypeptidase CP4 and amidohydrolase ADH2, and the two hydrolases are sole agents in strain CW239 for OTA degradation. Hereinto, the ADH2 was the overwhelming efficient hydrolase, and the two types of hydrolases co-degraded OTA in CW239 by synergistic effect. The results of this study are highly significant to ochratoxin A contamination control during agro-products production and postharvest.
赭曲霉毒素 A（OTA）是一种广泛污染农产品的毒性次生代谢物，对人类健康构成重大饮食风险。先前，从 Lysobacter sp. CW239 中鉴定出一种羧肽酶 CP4 具有 OTA 降解活性，但降解活性远低于其宿主菌株 CW239。在本研究中，从该菌株中筛选出一种酰胺水解酶 ADH2 用于 OTA 水解。结果表明，1.0μg/mL rADH2 在 5min 内可完全降解 50μg/L 的 OTA，表明其具有超高的活性。同时，菌株 CW239 中的两种水解酶（CP4 和 ADH2）表现出相同的降解方式，将 OTA 转化为 ochratoxin α（OTα）和 l-β-苯丙氨酸。基因突变体（Δcp4、Δadh2 和 Δcp4-adh2）测试结果表明，OTA 被羧肽酶 CP4 和酰胺水解酶 ADH2 共同降解，这两种水解酶是 CW239 中 OTA 降解的唯一酶。其中，ADH2 是具有压倒性高效的水解酶，两种类型的水解酶通过协同作用共同降解 CW239 中的 OTA。本研究结果对农产品生产和产后过程中赭曲霉毒素 A 污染控制具有重要意义。
