CAS Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China.
CAS Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China.
Chemosphere. 2021 Jan;262:127818. doi: 10.1016/j.chemosphere.2020.127818. Epub 2020 Jul 30.
Yellow mealworms (Tenebrio molitor larvae) are capable of biodegrading polystyrene (PS) and low-density polyethylene (LDPE). This study tested biodegradation of one expanded PS (EPS) with a weight-average molecular weight (M) 256.4 kDa and two LDPE foams with respective M of 130.6 kDa (PE-1) and 288.7 kDa (PE-2) in T. monitor larvae obtained in Beijing, China. The larvae consumed EPS and both LDPEs over a 60 day. Fourier transform infrared spectroscopy and thermogravimetric analyses of frass confirmed the formation of new oxygen-containing functional groups, as well as a change in physical property and chemical modification, indicating that biodegradation of EPS and LDPE occurred. Gel permeation chromatography analysis confirmed broad depolymerization of EPS and PE-1 (i.e., a decrease in both M and a number-average molecular weight (M)) but revealed limited extent depolymerization of PE-2 (i.e., increase in M and decrease in M). For all materials, the size-average molecular weight (M) was decreased. Biodegradation and oxidation of EPS and LDPE were confirmed using FTIR and TGA analysis. Depression of gut microbes by the antibiotic gentamicin resulted in significant inhibition of EPS depolymerization but did not stop LDPE depolymerization, resulting in the increase in M and revealing that PS biodegradation was gut microbe-dependent but LDPE biodegradation was less dependent or independent of gut microbes. Gut microbial community analysis indicated that, as expected, under different dietary conditions, the intestinal flora significantly shifted to communities associated with biodegradation of EPS and LDPE. The results indicated the complexity and limitation of biodegradation of plastics in plastics-eating T. molitor larvae.
黄粉虫（Tenebrio molitor 幼虫）能够生物降解聚苯乙烯（PS）和低密度聚乙烯（LDPE）。本研究测试了一种重均分子量（Mw）为 256.4 kDa 的膨胀聚苯乙烯（EPS）和两种 LDPE 泡沫在来自中国北京的 T. 监测幼虫中的生物降解情况，两种 LDPE 泡沫的 Mw 分别为 130.6 kDa（PE-1）和 288.7 kDa（PE-2）。幼虫在 60 天内消耗了 EPS 和两种 LDPE。虫粪的傅里叶变换红外光谱和热重分析证实了新含氧官能团的形成，以及物理性质的变化和化学修饰，表明 EPS 和 LDPE 的生物降解发生了。凝胶渗透色谱分析证实了 EPS 和 PE-1 的广泛解聚（即 Mw 和数均分子量（Mn）的降低），但揭示了 PE-2 的解聚程度有限（即 Mw 的增加和 Mn 的降低）。对于所有材料，重均分子量（Mw）都降低了。使用傅里叶变换红外光谱和热重分析证实了 EPS 和 LDPE 的生物降解和氧化。抗生素庆大霉素对肠道微生物的抑制导致 EPS 解聚显著抑制，但不能阻止 LDPE 解聚，导致 Mw 增加，表明 PS 生物降解依赖于肠道微生物，但 LDPE 生物降解对肠道微生物的依赖性较小或不依赖于肠道微生物。肠道微生物群落分析表明，正如预期的那样，在不同的饮食条件下，肠道菌群明显向与 EPS 和 LDPE 生物降解相关的群落转移。结果表明，在食用塑料的 T. 幼虫中，塑料的生物降解具有复杂性和局限性。
