Pure-culture and enzymatic assay for starch-polyethylene degradable plastic biodegradation with Streptomyces species

Anthony L. Pometto, Kenneth E. Johnson, Meera Kim

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Eleven starch-polyethylene degradable plastic films were prepared from masterbatches from Archer Daniels Midland Inc. (ADM), EcoStar Inc. (SLS), and Fully Compounded Plastic Inc. The biodegradability of initial and 70°C heat-treated materials was determined using a pure-culture assay with Streptomyces badius 252, S. setonii 75Vi2, or S. viridosporus T7A or without bacterial culture (control). Films were treated with 10-fold S. setonii culture concentrates and compared with inactive enzyme controls. Changes in each films mechanical property, molecular weight distribution, and Fourier-transformed infrared spectrum (FT-IR) were determined, and results were evaluated for significant differences by analysis of variance. Cell mass accumulation on each film was quite pronounced. In pure-culture studies, biodegradation was demonstrated for ADM-7 and SLS-2 initial films and for ADM-6 heat-treated films, whereas after 3-week treatment with active S. setonii culture concentrates (enzyme assay), reductions in mechanical properties and changes in FT-IR spectrum were illustrated by all the films except SLS-2. Thus the absence of biofilm formation on the film surface permitted enzymatic attack of the materials. Furthermore, inhibition of chemical oxidative degradation in the pure-culture assay was demonstrated for ADM-11, SLS-5, and SLS-10 initial materials and for ADM-4, ADM-7, SLS-8, and SLS-10 heat-treated films. These data suggest that biological and chemical degradation were directly affected by the reduction in oxygen tension on the plastic film surface due to cell mass accumulation. This same phenomenon could be the cause for slow degradation rates in nature.

Original languageEnglish
Pages (from-to)213-221
Number of pages9
JournalJournal of Environmental Polymer Degradation
Volume1
Issue number3
DOIs
StatePublished - Jul 1993

Keywords

  • Biodegradation
  • Streptomyces
  • chemical degradation
  • degradable plastics
  • starch-polyethylene

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