New Hydrolase from Aeromicrobium sp. HA for the Biodegradation of Zearalenone: Identification, Mechanism, and Application

Abstract

Zearalenone (ZEN) is an estrogenic mycotoxin most frequently found in cereals that can cause reproductive disorders in livestock and pose a severe threat to animal husbandry. In this study, we isolated a ZEN-degrading Aeromicrobium strain from soil and found that ZenH, a hydrolase, is responsible for the hydrolysis of ZEN through comparative proteomics and biochemical studies. ZenH exhibited the highest similarity with lactone hydrolase ZHD607 from Phialophora americana at 21.52%. ZenH displayed maximal enzymatic activity at pH 7.0 and 55 °C with a Michaelis constant of 12.64 μM. The catalytic triad of ZenH was identified as S117-D142-H292 by molecular docking and site-directed mutagenesis. ZenH catalyzed the hydrolysis of ZEN to a novel metabolite, (S,E)-4-hydroxy-2-(10-hydroxy-6-oxoundec-1-en-1-yl)-7-oxabicyclo[4.2.0]octa-1,3,5-trien-8-one, which exhibited significantly lower estrogenic toxicity than ZEN. This study illustrates a novel ZEN-degrading enzyme and reveals a new degradation product. Furthermore, the enzyme showed good potential for detoxifying ZEN during food processing.

Mining Lactonase Gene from Aflatoxin B1-Degrading Strain Bacillus megaterium and Degrading Properties of the Recombinant Enzyme

“…ZEN was detected using an FLD detector at 236 nm. 25 The mobile phase comprised A (water) and B (methanol) at a ratio of 20:80 (v/v). DON was detected at 218 nm, with the mobile phase comprising A (water) and B (methanol) in a ratio of 70:30 (v/v).…”

“…The verified plasmid was transformed into E. coli BL21 (DE3). 25 Transformant E. coli BL21 (DE3) harboring the recombinant vector were chosen based on positive outcomes and then grown in LB liquid medium plus 50 μg/mL kanamycin. Cultures were incubated at 220g at 37 °C until the optical density at 600 nm reached 0.6−0.8.…”

Insights into the Unusual Activity of a Novel Homospermidine Synthase with a Promising Application to Produce Spermidine

“…The cells were washed with 20 mM phosphoric acid buffer (pH 7.5), broken with an ultrasonic homogenizer (Scientz, Ningbo, China) on ice (power of 30%, broken for 1 s, spaced for 3 s, a total of 15 min), and centrifuged for 20 min at 8000 × g to acquire the supernatant. Protein was purified and desalinated using a 5 mL Ni-HisTrap column and a HisTrap desalting column (GE Healthcare, Shanghai, China) . Equilibration buffer (20 mM Tris and 150 mM NaCl, pH 8.0) and elution buffer (20 mM Tris, 150 mM NaCl, and 1 M imidazole, pH 8.0) were prepared.…”

“…Protein was purified and desalinated using a 5 mL Ni-HisTrap column and a HisTrap desalting column (GE Healthcare, Shanghai, China). 21 Equilibration buffer (20 mM Tris and 150 mM NaCl, pH 8.0) and elution buffer (20 mM Tris, 150 mM NaCl, and 1 M imidazole, pH 8.0) were prepared. After the protein binds to the column, the impurities are removed with a solution containing 5% elution buffer, and the recombinant protein is eluted with a solution containing 15% elution buffer.…”

Identification and Modification of Enzymatic Substrate Specificity through Residue Alteration in the Cap Domain: A Thermostable Zearalenone Lactonase

“…For example, the Aeromicrobium sp. HA, isolated from soil by Hu et al, was found to completely degrade ZEN within three days . Through comparative proteomics and biochemical investigations, a novel ZEN hydrolase (ZenH) was identified.…”