Biodegradation of photodegradable coating materials used for coated fertilizers by soil microorganisms

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Photodegradable polyethylenes, which produce alkane-like substances following sustained exposure to sunlight, are used as a coating material for some agricultural fertilizers. This study examines the biodegradability of these substances in two different agricultural soil types using the biochemical oxygen demand (BOD) method After a 21 day test period, high molecular weight photodegradation products showed little biodegradation. However, the low molecular weight fractions extracted from the photodegradation products using hexane showed biodegradabilities of 8% to 18% within the same 21 day period. Furthermore, the two soils were found to have different biodegradation patterns, possibly due to differences in the microbial communities present. These results suggest that microbes that can degrade and utilize the low molecular weight photodegradation products of photodegradable polyethylenes exist in the tested agricultural soils.Microorganisms utilizing alkanes are widely distributed in nature, and such microorganisms are isolated from various locations. However, microorganisms that degrade and utilize long-chain n-alkanes have not been reported from acidic soil. In this study, we examined highly acidic soil samples (pH 3.2) collected from a tea field, and attempted to isolate and identify microorganisms utilizing long-chain n-alkanes. No bacteria utilizing long-chain n-alkanes were found, but filamentous fungi with the ability of utilizing long-chain n-alkanes were obtained. Phylogenetic analysis using SSU rDNA sequences suggested that the fungi obtained were Cordyceps sp. and Mortierella sp.