Poly β-hydroxybutyrate depolymerase (PhaZ) in Azospirillum brasilense and characterization of a phaZ mutant

Daniel Kadouri, Edouard Jurkevitch, Yaacov Okon

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Like many other prokaryotes, rhizobacteria of the genus Azospirillum produce high levels of poly-β-hydroxybutyrate (PHB) under sub-optimal growth conditions. Utilization of PHB by bacteria under stress has been proposed as a mechanism that favors their compatible establishment in competitive environments. PHB depolymerase (PhaZ) is an essential enzyme in PHB degradation. The phaZ gene was identified in Azospirillum brasilense, cloned, sequenced, and shown to be located on the chromosome. Insertion of a kanamycin-resistant cassette within phaZ of A. brasilense resulted in a phaZ mutant that was unable to degrade PHB; however, carbon source utilization was similar in both the wild-type and the mutant strain. The ability of the wild-type to endure starvation conditions, ultraviolet irradiation, heat, and osmotic shock, and to grow in the presence of hydrogen peroxide was higher than that of the mutant strain. By contrast, the ability of the phaZ mutant strain to endure desiccation was higher than that of the wild-type strain. No differences between the strains were seen in their ability to endure sonication, or to survive in carrier materials used for soil inoculants. In addition, motility was the same between the two strains, whereas cell aggregation and exopolysaccharide production were higher in the wild-type than in the phaZ mutant strain.

Original languageEnglish (US)
Pages (from-to)309-318
Number of pages10
JournalArchives of Microbiology
Volume180
Issue number5
DOIs
StatePublished - Nov 1 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Biochemistry
  • Molecular Biology
  • Genetics

Keywords

  • Azospirillum brasilense
  • PHA depolymerase (Phaz)
  • Poly-β-hydroxybutyrate (PHB)

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