Microbial Degradation of UV-Pretreated Low-Density Polyethylene Films by Novel Polyethylene-Degrading Bacteria Isolated from Plastic-Dump Soil
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Eleven effective low-density polyethylene (LDPE)-degrading bacterial strains were isolated and identified from landfill soil containing large amounts of plastic materials. The isolates belonged to 8 genera, and included Pseudomonas (areroginosa and putida), Sphingobacterium (moltivorum), Delftia (tsuruhatansis), Stentrophomonas (humi and maltophilia), Ochrobacterum (oryzeae and humi), Micrococcus (luteus), Acinetobacter (pitti), and Citrobacter (amalonaticus). Abiotic degradation of LDPE films by artificial and natural ultraviolet (UV)-exposure was analyzed by FT-IR spectroscopy. LDPE films treated with UV-radiation were also inoculated with the isolates and biofilm production and LDPE degradation were measured. Surface changes to the LDPE induced by bacterial biofilm formation were visualized by Scanning Electron Microscopy. The most active bacterial isolate, IRN19, was able to degrade polyethylene film by 26.8 ± 3.04% gravimetric weight over 4 weeks. Analysis of 16S rRNA sequence of this isolate revealed 96.97% similarity in sequence to Acinetobacter pitti, which has not previously been identified as a polyethylene-degrading bacterium. Also, most the effective biofilm forming isolate, IRN11, displayed the highest cell mass production (6.29 ± 0.06 log cfu/cm2) after growth on LDPE films, showed 98.74% similarity to Sphingobacterium moltivourum.
KeywordsBiodegradation Polyethylene-degrading bacteria Biofilm formation SEM FTIR
The authors wish to thank Prof. David B. Levin from University of Manitoba for revising the MS and the “Research Center of Mashhad Islamic Council” for partial financial support of this work.
Funding was provided by Mashhad Islamic City Council Research Center (Grant No. 1310).
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