Biocatalytic efficacy of immobilized cells of Chryseobacterium sp. Alg-SU10 for simultaneous hydrolysis of urethane and urea

Abstract

Urethane, a carcinogenic and teratogenic compound, in fermented foods and alcoholic beverages can be eliminated either by direct hydrolysis with urethanase, or by hydrolysis of its precursor molecule urea with acid urease. In the present study, a potent bacterium, which concomitantly produced urethanase and acid urease, was isolated from the decomposed Sargassum species. This bacterial isolate was identified as Chryseobacterium sp. Alg-SU10 by the 16S rRNA gene sequencing approach. The biocatalytic efficacy of the calcium alginate immobilized cells of this bacterium for the hydrolysis of urethane and urea was evaluated by characterizing urethanase and acid urease. The immobilized biocatalyst displayed maximal urethanase and urease activities at pH 5, and retained more than 96% of enzymatic activity at 15% (v/v) ethanol. The values of activation energy, enthalpy and entropy of catalysis were calculated as 43.3 kJ/mol, 40.8 kJ/mol and –116 J/mol/K, respectively, for urethanase and 38.1 kJ/mol, 35.6 kJ/mol and –77.8 J/mol/K, respectively, for acid urease. The overall results indicate the biocatalytic potential of immobilized cells of Chryseobacterium sp. Alg-SU10 for efficient abatement of urethane. This is the first report describing the thermodynamic characteristics of urethanase and acid urease co-produced by Chryseobacterium sp.

Keywords:

• Acid urease
• Chryseobacterium
• immobilization
• Sargassum
• thermodynamics
• urethanase

Acknowledgements

The author thanks the Head, Department of Biological and Chemical Sciences, The University of the West Indies (UWI), Cave Hill Campus, for providing necessary facilities.

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

This research was partly supported by the UWI Campus Research Awards Fund.