Genome-Guided Identification of an OTA-Degrading Amidohydrolase AMH2102 from Acinetobacter kookii AK4 with Enhanced Soluble Expression in Escherichia coli

Ochratoxin A (OTA) is a globally distributed mycotoxin that poses serious threats to food safety and human health due to its nephrotoxic, hepatotoxic, and carcinogenic properties. Previous enzymatic detoxification strategies for OTA have been constrained by low degradation efficiency or poor soluble expression of highly active enzymes. In this study, a bacterial strain with strong OTA-degrading activity was isolated and identified as <i>Acinetobacter kookii</i> AK4, which degraded 95.44% of 1 μg/mL OTA within 6 h. The predominant OTA-degrading activity was derived from intracellular enzymes. Through genome mining and experimental validation, <i>gene2102</i> was identified as encoding an amidohydrolase. The enzyme was designated AMH2102 and was heterologously expressed in <i>Escherichia coli</i>. Codon optimization combined with fusion of an N-terminal SUMO tag increased the soluble expression of AMH2102 by 14.81-fold, enabling complete (100%) OTA degradation within 3 min. Overall, this study achieved the identification of an efficient OTA-degrading strain and enzyme and explored strategies for improving enzyme expression, yielding effective outcomes that provide useful references for future studies on strain mining and enzyme engineering.