赭曲霉毒素A
酶
大肠杆菌
水解酶
化学
生物化学
羧酸酯酶
酶分析
生物
分子生物学
食品科学
基因
真菌毒素
作者
Israt Jahan,Bowen Tai,Junning Ma,Sarfaraz Hussain,Haolan Du,Lei Guo,Gang Wang,Tosin Victor Adegoke,Longxue Ma,Fuguo Xing
标识
DOI:10.1021/acs.jafc.3c01910
摘要
Contamination of foods and feeds with Ochratoxin A (OTA) is a global problem, and its detoxification is challenging. In this study, Bacillus velezensis IS-6 culture isolate supernatant degraded 1.5 g/mL OTA by 89% after 24 h of incubation at 37 °C, whereas viable cells and intra-cell extracts were less effective. The OTA degradation by B. velezensis IS-6 was an enzymatic process mediated by the culture supernatant. The degradation activity was optimal at 37 °C and pH 7.0, and Fe2+ and Cu2+ ions enhanced the OTA degradation. The LC–MS/MS analysis confirmed that structure of OTA was modified, resulting in the production of OTα that was less toxic than OTA. The transcriptomic analysis of B. velezensis IS-6 showed that 38 differentially expressed genes (DEGs) were significantly up-regulated, and 24 DEGs were down-regulated after treatment with OTA. A novel OTA degradation enzyme Nudix hydrolase Nh-9 was successfully cloned and characterized from the up-regulated genes. The recombinant Nh-9 enzyme was overexpressed in Escherichia coli BL21 and purified by affinity chromatography, exhibiting 68% degradation activity against 1.0 μg/mL OTA at 37 °C in 24 h. The degraded product by the Nh-9 enzyme was identified as the less toxic OTα by LC–MS/MS. According to the findings, it can be inferred that Nh-9 is the main OTA-degrading enzyme in B. velezensis IS-6. Furthermore, OTA may be co-degraded by Nh-9, carboxylesterase, signal peptidase, and other degrading agents that are yet to be discovered in this strain.
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