SYNOPSISThe biodegradation of several polymers that had been buried under soil for over 32 years was examined. No evidence of biodegradation was found for polystyrene, polyvinylchloride, and urea formaldehyde resin. A remarkable degradation was indicated for low density polyethylene thin films which were directly in contact with soil. Severely degraded parts of the film is characterized by whitening. Many small holes were recognized on the surface of the whitened part. The whitened part is specific for the growth of hyphae. FT-IR spectra of the whitened part showed a characteristic band in the vicinity of 1640 cm-' which was assigned to the stretching vibration of C=C bond. Although the part which was not in contact with soil was clear, it also showed evidence of degradation from the presence of carbonyl band in FT-IR. It was suggested that the degradation of the clear part is due to the usual thermo-oxidative process, while the degradation of the whitened part is due to the biotic process. 0

No abstract

ABSTRACT:The molecular weight reduction of low-density polyethylene (LDPE) buried under bioactive soil for 32-37 years was examined by GPC. Microscope IR spectra of the surface of the degraded sample showed the characteristic feature of biodegradation, while the inner part of the sample was almost unchanged. The number average molecular weight (M n ) of the surface was reduced to almost one-half of the inner part. Moreover, a low-molecular-weight component around a molecular weight of 10 3 was recognized for degraded samples. SEM observation suggested that the formation of the lowmolecular-weight components is the result of erosion due to enzymatic reaction. The results give evidence for the biodegradation of high-molecular-weight LDPE.

We have isolated and identified three types of low‐density polyethylene (LDPE) degrading microbes, for the first time, from soil which was sampled from the field. It has been studied that thermooxidized or UV irradiation LDPE are degraded when incubated with mold (Volke‐sepulveda et al., J Appl Polym Sci 2002, 83, 305; Yamada‐Onodera et al., Polym Degrad Stab 2001, 72, 323); however, there was no article so far reporting the isolation of these particular microbes from the environment. Here, the mechanism of biodegradation of LDPE by the three microbes is described. We used LDPE film, which was buried in soil and biodegraded, and the surrounding soil, located at Nogi Town, Tochigi Prefecture, Japan as the sources of sample for this study. The sample was added to a liquid medium, together with powder of a photodegraded, antioxidant‐free LDPE film, as the sole source of carbon. After enriched cultivation, three strains of microbes were separated from the medium. They were classified on the basis of LDPE degrading capabilities, confirmed by OH generation and degradation traces. Using “Bergey's Manual of Determinative Bacteriology,” the genera of the microbes were identified as Bacillus circulans, Bacillus brevies, and Bacillus sphaericus, which belong among the Natto bacteria, common in soil. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

No abstract