The role of the copper-binding enzyme - laccase - in the biodegradation of polyethylene by the actinomycete Rhodococcus ruber

Miriam Santo, Ronen Weitsman, Alex Sivan

Research output: Contribution to journalArticlepeer-review

172 Scopus citations

Abstract

Polyethylene is considered one of the most durable plastic polymers. Virtually, non-biodegradable polyethylene accumulates in the environment, thus posing an ecological threat to man and wildlife. We have previously isolated a strain of the actinomycete Rhodococcus ruber (designated C208; EC 1.10.3.2.) capable of utilizing and degrading polyethylene. Here, we report the role of the bacterial copper-binding enzyme, laccase, in the oxidation and degradation of polyethylene by this strain. Copper markedly affected the induction and activity of laccase, resulting in polyethylene degradation. mRNA quantification by RT-PCR, revealed a 13-fold increase in laccase mRNA levels, in copper-treated cultures compared with the untreated control. Addition of copper to C208 cultures containing polyethylene enhanced the biodegradation of polyethylene by 75%, as compared with the non-amended control. Furthermore, when an extracellular isoform of laccase collected from the media of copper-induced cells was incubated with polyethylene, reductions of 20% and 15% were obtained in the Average Molecular Weight (Mw) and Average Molecular Number (Mn) with the polymer, respectively. FTIR analysis of similar polyethylene films incubated with the extracellular laccase exhibited an increase in the carbonyl peak, indicating that enzymatic oxidation by laccase plays a major role in the biodegradation of polyethylene.

Original languageEnglish
Pages (from-to)204-210
Number of pages7
JournalInternational Biodeterioration and Biodegradation
Volume84
DOIs
StatePublished - 1 Oct 2013

Keywords

  • Biodegradation
  • Copper-binding enzymes
  • Laccase
  • Polyethylene

ASJC Scopus subject areas

  • Microbiology
  • Biomaterials
  • Waste Management and Disposal

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