Degradation of poly(3-hydroxybutyrate), PHB, by bacteria and purification of a novel PHB depolymerase fromComamonas sp
| Autor: | Rahim Bahodjb Habibian, Alexander Steinbüchel, I. Knoke, Hans G. Schlegel, Dieter Jendrossek |
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| Rok vydání: | 1993 |
| Předmět: |
chemistry.chemical_classification
0303 health sciences Environmental Engineering Polymers and Plastics biology Strain (chemistry) 030306 microbiology Chemistry technology industry and agriculture macromolecular substances General Medicine biology.organism_classification Polyhydroxyalkanoates 03 medical and health sciences chemistry.chemical_compound Hydrolysis Enzyme Biochemistry Materials Chemistry lipids (amino acids peptides and proteins) PMSF Ammonium sulfate precipitation Bacteria 030304 developmental biology Phenylmethylsulfonyl Fluoride |
| Zdroj: | Journal of Environmental Polymer Degradation. 1:53-63 |
| ISSN: | 1572-8900 |
| DOI: | 10.1007/bf01457653 |
| Popis: | Bacteria capable of growing on poly(3-hydroxybutyrate), PHB, as the sole source of carbon and energy were isolated from various soils, lake water, activated sludge, and air. Although all bacteria utilized a wide variety of monomeric substrates for growth, most of the strains were restricted to degrade PHB and copolymers of 3-hydroxybutyrate and 3-hydroxyvalerate, P(3HB-co-3HV). Five strains were also able to decompose a homopolymer of 3-hydroxyvalerate, PHV. Poly(3-hydroxyoctanoate), PHO, was not degraded by any of the isolates. One strain, which was identified asComamonas sp., was selected, and the extracellular depolymerase of this strain was purified from the medium by ammonium sulfate precipitation and by chromatography on DEAE-Sephacel and Butyl-Sepharose 4B. The purified PHB depolymerase was not a glycoprotein. The relative molecular masses of the native enzyme and of the subunits were 45,000 or 44,000, respectively. The purified enzyme hydrolyzed PHB, P(3HB-co-3HV), and—at a very low rate—also PHV. Polyhydroxyalkanoates, PHA, with six or more carbon atoms per monomer or characteristic substrates for lipases were not hydrolyzed. In contrast to the PHB depolymerases ofPseudomonas lemoignei andAlcaligenes faecalis T1, which are sensitive toward phenylmethylsulfonyl fluoride (PMSF) and which hydrolyze PHB mainly to the dimeric and trimeric esters of 3-hydroxybutyrate, the depolymerase ofComamonas sp. was insensitive toward PMSF and hydrolyzed PHB to monomeric 3-hydroxybutyrate indicating a different mechanism of PHB hydrolysis. Furthermore, the pH optimum of the reaction catalyzed by the depolymerase ofComamonas sp. was in the alkaline range at 9.4. |
| Databáze: | OpenAIRE |
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