Purification and Properties of an Extracellular Polyhydroxybutyrate Depolymerase from Pseudomonas mendocina DSWY0601 |
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Authors: | WANG Yan LI Fan WANG Zhan-yong LIU Dong-bo XIA Hong-mei LIU Ling-fei CHEN Shan |
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Institution: | 1. School of Life Sciences, Northeast Normal University, Changchun 130024, P. R. China;
2. School of Environmental and Biological Engineering, Liaoning Shihua University, Fushun 113001, P. R. China |
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Abstract: | An extracellular polyhydroxybutyrate(PHB) depolymerase was purified to homogeneity from the culture supernatant of a PHB-degrading bacterium, Pseudomonas mendocina DSWY0601, which was isolated from brewery sewage for the ability to form clear zones on the PHB mineral agar plates. The molecular weight of the purified PHB depolymerase as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) was approximately 59800 at the optimal temperature and pH value being 50 ℃ and 8.5, respectively. PHB depolymerase was stable in a temperature range of 20―50 ℃ and sensitive to pH value within a pH range of 8.0―9.5. PHB depolymerase degraded poly-3-hydroxybutyrate-co-4-hydroxybutyrate(P3/4HB) and poly-3-hydroxybutyrate-co-3- hydroxyvalerate(PHBV) but did not degrade poly(lactic acid)(PLA), poly(butylene succinate)(PBS) or poly- (caprolactone)(PCL). PHB depolymerase was sensitive to phenylmethylsulfonyl fluoride(PMSF), H2O2 and SDS. The main product after enzymatic degradation of PHB was indentified as 3-hydroxbutyrate monomer(3HB) by mass spectrometric analysis, suggesting that PHB depolymerase acted as an exo-type hydrolase. Analysis of phaZpm gene reveals that PHB depolymerase is a typical denatured short-chain-length PHA(dPHASCL, PHA=polyhydroxyalkanoate) depolymerase containing catalytic domain, linker and substrate-binding domain. |
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Keywords: | Polyhydroxybutyrate(PHB) PHB depolymerase Pseudomonas mendocina Polyhydroxyalkanoate(PHA) |
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