State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
Sci Total Environ. 2021 Oct 1;789:147915. doi: 10.1016/j.scitotenv.2021.147915. Epub 2021 May 21.
Tenebrio obscurus (Coleoptera: Tenebrionidae) larvae are capable of biodegrading polystyrene (PS) but their capacity for polyethylene (PE) degradation and pattern of depolymerization remains unknown. This study fed the larvae of T. obscurus and Tenebrio molitor, which have PE degrading capacity, two commercial low-density PE (LDPE) foams i.e., PE-1 and PE-2, with respective number-average molecular weights (M) of 28.9 and 27.3 kDa and weight-average molecular weights (M) of 342.0 and 264.1 kDa, over a 36-day period at ambient temperature. The M of residual PE in frass (excrement) of T. obscurus, fed with PE-1 and PE-2, decreased by 45.4 ± 0.4% and 34.8 ± 0.3%, respectively, while the respective decrease in frass of T. molitor was 43.3 ± 0.5% and 31.7 ± 0.5%. Data analysis showed that low molecular weight PE (<5.0 kDa) was rapidly digested while longer chain portions (>10.0 kDa) were broken down or cleaved, indicating a broad depolymerization pattern. Mass balance analysis indicated nearly 40% of ingested LDPE was digested to CO. Antibiotic suppression of gut microbes in T. molitor and T. obscurus larvae with gentamicin obviously reduced their gut microbes on day 15 but did not stop depolymerization because the M, Mw and size- average molecular weight (M) decreased. This confirmed that LDPE biodegradation in T. obscurus was independent of gut microbes as observed during previous PS degradation in T. molitor, suggesting that the intestinal digestive system could perform LDPE depolymerization. High-throughput sequencing revealed significant shifts in the gut microbial community during bran-fed and unfed conditions in response to LDPE feeding in both Tenebrio species. The respective predominant gut genera of Spiroplasma sp. and Enterococcus sp. were observed in LDPE-fed T. molitor and T. obscurus larvae.
暗黑鳃金龟（鞘翅目：金龟子科）幼虫能够生物降解聚苯乙烯（PS），但它们对聚乙烯（PE）的降解能力和聚合物的解聚模式尚不清楚。本研究以具有 PE 降解能力的暗黑鳃金龟和黄粉虫幼虫为研究对象，在环境温度下，用两种商业低密度聚乙烯（LDPE）泡沫，即 PE-1 和 PE-2，喂养它们 36 天。PE-1 和 PE-2 的数均分子量（M）分别为 28.9 和 27.3 kDa，重均分子量（M）分别为 342.0 和 264.1 kDa。暗黑鳃金龟和黄粉虫幼虫粪便中残留的 PE 的 M 分别下降了 45.4±0.4%和 34.8±0.3%，而黄粉虫幼虫粪便中残留的 PE 分别下降了 43.3±0.5%和 31.7±0.5%。数据分析表明，低分子量 PE（<5.0 kDa）迅速被消化，而较长链部分（>10.0 kDa）则被分解或裂解，表明存在广泛的解聚模式。质量平衡分析表明，近 40%的摄入 LDPE 被消化为 CO。用庆大霉素抑制黄粉虫和暗黑鳃金龟幼虫的肠道微生物，在第 15 天明显减少了它们的肠道微生物，但并没有阻止解聚，因为 M、Mw 和重均分子量（M）都降低了。这证实了 LDPE 在暗黑鳃金龟中的生物降解与肠道微生物无关，正如之前在黄粉虫中观察到的 PS 降解一样，这表明肠道消化系统可以进行 LDPE 的解聚。高通量测序揭示了在两种暗黑鳃金龟和黄粉虫中，在 bran-fed 和 unfed 条件下，以及在 LDPE 喂养下，肠道微生物群落发生了显著变化。在 LDPE 喂养的黄粉虫和暗黑鳃金龟幼虫中，分别观察到主要的肠道属为螺旋体属（Spiroplasma sp.）和肠球菌属（Enterococcus sp.）。
