Identification, Characterization, and Application of a Novel Highly Efficient Thermostable Patulin-Degrading Enzyme from Acetomicrobium hydrogeniformans

Mycotoxin patulin poses serious threats to human health by contaminating food and food products; biological detoxification of patulin by using enzymes is a promising method, and the key is an effective enzyme. Here, a thermostable patulin-degrading lipase, Ah Est from Acetomicrobium hydrogeniformans, is identified and characterized. It retains over 50% residual activity after heat treatment at 85 °C for 120 min, and its thermostability is the highest of known patulin-degrading enzymes. It converts patulin efficiently to a new low-toxicity product 2-(2-hydroxy-4-oxodihydro-2H-pyran-3(4H) -ylidene) acetic acid, different from the previously reported hydrolysis product. Structural modeling analysis reveals Ah Est’s catalytic triad and patulin hydrolysis mechanism. Variant Ah EstE49A with higher catalytic efficiency is obtained by protein engineering on the substrate entrance tunnel; it can remove patulin in commercial apple juice at low enzyme load. The study of Ah Est adds to the knowledge of patulin enzymatic degradation and provides a candidate for patulin biodetoxification in the food industry.