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

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.