取食聚苯乙烯塑料对黄粉虫幼虫肠道微生物群落的影响

Feeding of polystyrene plastics affects the gut microbiota of Tenebrio molitor larvae

摘要:

随着塑料在人类社会中的普及，越来越多的废弃塑料及其前体物质被遗留在环境中，且其在自然环境中的降解速度十分缓慢，为此寻找有效的降解途径成为亟待解决的科学问题。【目的】探究利用黄粉虫(Tenebrio molitor)幼虫取食聚苯乙烯对其肠道微生物种群及其代谢路径的响应，以期通过食物诱导寻找一条生物降解和利用聚苯乙烯的有效途径。【方法】以聚苯乙烯为唯一食物来源喂饲黄粉虫幼虫，通过测量幼虫存活率和个体的体重来测定其生长发育情况；通过对其肠道内容物进行16S rRNA基因测序，分析其肠道菌群结构的变化；采用京都基因与基因组百科全书(Kyoto encyclopedia of genes and genomes, KEGG)分析法来预测相关功能基因。【结果】取食聚苯乙烯黄粉虫幼虫存活率和体重均下降，聚苯乙烯塑料明显减少；取食聚苯乙烯的黄粉虫幼虫肠道菌群丰度与多样性明显减少，在门水平，取食聚苯乙烯的黄粉虫幼虫肠道的优势菌为变形菌门(Proteobacteria)、软壁菌门(Tenericutes)和厚壁菌门(Firmicutes)；在属水平，取食聚苯乙烯的黄粉虫幼虫肠道优势菌为螺旋体菌属(Spiroplasma)、肠杆菌(Enterobacillus)和大肠埃氏-志贺氏菌(Escherichia-Shigella)；通过KEGG功能预测，找到与芳香类和烷烃降解功能相关的基因共18种，取食聚苯乙烯组黄粉虫幼虫肠道菌群降解聚苯乙烯相关通路丰度升高，相关基因表达增强。【结论】聚苯乙烯可以为黄粉虫幼虫生长发育提供一定的物质和能量，且能够使其完成一个世代过程；幼虫长时间取食单一食物后，其肠道菌群结构会发生目标性变化，利用KEGG预测能够找到与聚苯乙烯代谢相关的基因，为后续研究工作提供了有价值的依据。

Abstract:

With the popularity of plastics in the human society, more and more waste plastics and their precursors are left in the environment. In view of the slow degradation of the plastics in the natural environment, it is in urgent need to develop an effective degradation pathway. [Objective] To investigate the responses of the gut microbiota and metabolic pathways in Tenebrio molitor larvae to the feeding of polystyrene, and find an effective way to biodegrade and utilize polystyrene through food intake. [Methods] The larvae were fed with polystyrene as the only food source, and the survival rate and body weight of the larvae were recorded. The changes in the structure of gut microbiota were analyzed by 16S rRNA gene sequencing of the gut contents. Kyoto encyclopedia of genes and genomes (KEGG) enrichment was performed to predict the relevant functional genes. [Results] The survival rate and body weight of the T. molitor larvae fed with polystyrene decreased, and polystyrene plastic was significantly reduced. The abundance and diversity of gut microbiota significantly decreased in the T. molitor larvae fed with polystyrene. The dominant phyla in the gut were Proteobacteria, Tenericutes, and Firmicutes, and the dominant genera were Spiroplasma, Enterobacillus, and Escherichia-Shigella. KEGG analysis predicted a total of 18 genes involved in aromatic and alkane degradation. The abundance of the pathways associated with polystyrene degradation by the gut microbiota of T. molitor larvae feeding on polystyrene increased and the expression of related genes was up-regulated. [Conclusion] Polystyrene can provide certain material and energy for the growth and development of T. molitor larvae and enable them to complete a generation. After the larvae feed on a single food source for a long time, their gut microbiota structure will undergo targeted changes. KEGG prediction can identify the genes associated with polystyrene metabolism, which provides a valuable basis for the subsequent research.