Isolation of Poly(3-Hydroxybutyrate) (PHB)-degrading Microorganisms and Characterization of PHB-depolymerase from Arthrobacter sp. strain W6

Abstract

Microbial degraders of poly(3-hydroxybutyrate) (PHB) were isolated from soil. Arthrobacter sp. strain W6 used not only PHB as a carbon source, but also PHAs such as poly(3-hydroxybutyrate-co-[5%]3-hydroxyvalerate, poly(3-hydroxybutyrate-co-[14%]3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-[22%]3-hydroxyvalerate). PHB-depolymerase was purified to homogeneity from the culture broth of Arthrobacter sp. strain W6 by a procedure involving DEAE- and butyl-Toyopearl column chromatographies. The M_r of the enzyme was estimated to be about 47,000 by SDS-polyacrylamide gel electrophoresis. The enzyme was most active at pH 8.5 and 50°C, and was inhibited by phenylmethylsulfonyl fluoride, Hg²⁺, Ag⁺, and Pb²⁺.