The gene encoding an esterase enzyme was cloned from a metagenomic library of cow rumen bacteria. The esterase gene (est2R) was 2,120 bp in length, encoding a protein of 516 amino acid residues with a calculated molecular weight of 57,286 Da. The molecular weight of the enzyme was estimated to be 57,000 Da by SDS-PAGE. Est2R shared 35.6% amino acid identity with esterase (CAH19079) of uncultured prokaryote. The Est2R was most active at 20-40°C, and showed optimum at 30°C and pH 8.0. The most activity of Est2R for the different chain length of p-nitrophenyl ester group as substrate was p-nitrophenyl acetate. Moreover, the enzyme was found to be most active without organic solvent, followed by 98% active with ethanol, and the enzyme activity was highly affected by the acetonitrile. The enzyme was significantly inhibited by Zn2+ but stimulated by Ca2+. So, novel esterase gene est2R is likely to obtain from cow rumen metagenome and supposed to use for industrial purpose.

• Tae-Ho Kang(Division of Applied Life Science (BK21 Program), Gyeongsang National University)
• Min-Keun Kim(Gyeongsangnam-do Agricultural Research and Extension Service)
• Tae-Yang Kim(Division of Applied Life Science (BK21 Program), Gyeongsang National University)
• Gi-Hwan Kim(Division of Applied Life Science (BK21 Program), Gyeongsang National University)
• Jung-Ho Kim(Department of Agricultural Chemistry, Sunchon National University)
• Hoon Kim(Department of Agricultural Chemistry, Sunchon National University)
• Han-Dae Yun(Division of Applied Life Science (BK21 Program), Gyeongsang National University, Research Institute of Agriculture and Life Science, Gyeongsang National University) Corresponding author