Urethane-hydrolyzing enzyme from Citrobacter sp

Area of Science:

• Biochemistry
• Microbiology
• Food Science

Background:

• Urethane, a known carcinogen, contaminates alcoholic beverages like wine and sake.
• Enzymatic degradation offers a potential method for removing urethane from beverages.

Purpose of the Study:

• To investigate the enzymatic decomposition of urethane.
• To identify and characterize a novel enzyme capable of urethane hydrolysis.

Main Methods:

• Isolation of Citrobacter sp. from mouse feces.
• Partial purification and characterization of the urethane-decomposing enzyme, named urethanase.
• Testing urethanase activity on various substrates and under different conditions (pH, alcohol concentration).

Main Results:

• Citrobacter sp. stoichiometrically decomposed urethane into ethanol and ammonia.
• Partially purified urethanase hydrolyzed carbamates and some amides, suggesting it is an amidase.
• Urethanase showed inactivity in high alcohol concentrations and acidic pH, rendering it ineffective for alcoholic beverage decontamination.

Conclusions:

• A novel amidase, urethanase, was identified with the ability to decompose urethane.
• The enzyme's limitations in alcohol and pH make it unsuitable for practical urethane removal from alcoholic beverages.