Biodegradation of synthetic polymers. II. A limited microbial conversion of 14C in polyethylene to 14CO2 by some soil fungi

Abstract

Polyethylene film synthetized with a randomly distributed 14C marker, was exposed to biodegradative impact by cultivated soil, a mixed culture of three wood rot fungi, and Fusarium redolens, isolated from soil experiments. The net values of 14CO2 evolution obtained by scintillation measurements amounted for about 0.5% in two years when calculated as a percentage of the total amount of radioactivity in the test sample. Both the soil and the different mold cultures reflected with very good agreement a definite liberation of 14CO2 from the 14C-labeled polyethylene film, significantly above that produced abiotically from aging samples. This is interpreted as due to an enzymatic cleavage and oxidative conversion of synthetic polymeric or oligomeric alkanes with limited chain length, accessible for biodegradation. Abiotic parallel experimental series maintained in a similar way, but either on distilled water only, or on media completed with silvernitrate in order to inhibit microbial growth, revealed slow but consequently progressing—evidently nonenzymatic—conversion of 14C to 14CO2. This is referred to as a borderline case of as unarrestable tardy mineralization process in the absence of light, however, autocatalytic and oxidative, an aging procedure in restricted sense.

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Affiliated Institutions

• KTH Royal Institute of Technology SE

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