Purification and Characterization of Poly(L-lactic acid) Depolymerase From Pseudomonas sp. Strain DS04-T

摘要

Poly(L-lactic acid) (PLA)-degrading Pseudomonas sp. strain DS04-T was isolated from an activated sludge sample. A novel PLA depolymerase with a molecular weight of 34 kDa was purified to homogeneity from the culture supernatant of strain DS04-T. The optimum pH and temperature of the PLA depolymerase are 8.5 and 50° C, respectively. The PLA depolymerase can also degrade triolein, poly(β-hydroxybutyrate), and poly(ε-caprolactone). Na^sup +^ and K^sup +^ enhance the enzyme activity, whereas Zn^sup 2+^, Mg^sup 2+^, Cu^sup 2+^, and Fe^sup 2+^ inhibit it. The inhibition effect of different chemicals on the PLA depolymerase activity were examined, in which ethylenediaminetetraacetic acid was found to have a significant inhibitory effect. The main degradation product of the depolymerase is identified as lactic acid monomer by mass spectrometric analysis. [PUBLICATION ABSTRACT]