The production conditions of 3-hydroxybutyrate (3-HB) monomers in submerged culture using Pseudomonas mendocina DS04-T as a degrading strain were optimized. The optimal culture medium constituents (w/v) were determined as follows: 0.5 % PHB, 0.15 % NH4Cl, 1.2 % Na2HPO4·12H2O, 0.3 % KH2PO4, 0.05 % MgSO4·7H2O, and 0.0005 % CaCl2·2H2O. The optimum parameters for liquid fermentation were as follows: temperature, 30 °C; inoculum content, 1.0 %; cultivation time, 18 h; initial pH, 7.0; volume of medium, 100 mL; and rotary speed, 180 rpm. Yield of 3-HB monomer and PHB depolymerase activity at optimized conditions were (56.4 ± 0.8) % and (57.4 ± 2.6) U/mL, respectively. The 3-HB monomer concentration obtained under optimized conditions was 1.5 times that obtained under the basic culture medium and initial conditions.
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This work was supported by National Natural Science Foundation of China (Grant No. 31100099), Science Project of Liaoning Province Education Office (L2011060) and Science Foundation of Liaoning Shihua University (No. 2011XJJ-025).