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

可光降解的聚乙烯在持续暴露在阳光下后会产生类似烷烃的物质，被用作一些农业肥料的包衣材料。本研究利用生化需氧量(BOD)法考察了这些物质在两种不同类型农业土壤中的生物降解性，经过21天的试验，高分子量的光降解产物几乎没有生物降解。而用正己烷从光降解产物中提取的低相对分子质量组分在相同的21天内具有8%~18%的生物降解率。此外，两种土壤被发现具有不同的生物降解模式，可能是由于存在的微生物群落的差异。这些结果表明，在供试的农业土壤中存在能够降解和利用低分子量光降解产物聚乙烯的微生物。利用烷烃的微生物在自然界中分布广泛，而且这种微生物来自不同的地点。然而，在酸性土壤中还没有降解和利用长链正构烷烃的微生物的报道。在这项研究中，我们检测了从茶田采集的高酸性土壤样本(pH 3.2)，并试图利用长链正构烷烃分离和鉴定微生物。没有发现利用长链正构烷烃的细菌，但获得了具有利用长链正构烷烃能力的丝状真菌。SSU rDNA序列的系统发育分析表明，所获得的真菌为冬虫夏草属。和被孢霉(Mortierella sp.)

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.