The impact of co-fed plastic diet on Tenebrio molitor gut bacterial community structure

Abstract

This study aimed to analyze the long-term impact of co-fed plastic diet on the bacterial community of self-sustaining laboratory populations of T. molitor fed with wheat bran with added polystyrene (PS), and low density polyethylene (LDPE) over a three year period. The most abundant phyla for all three populations were Firmicutes, Bacteroidota and Proteobacteria. PS group microbiota is similar to C group, pointing to a common bacterial species capable for degrading lignocellulose and PS, while consumption of LDPE caused a significant decrease of Bacteroidota and Actinobacteriota compared to both C and PS group, and Campylobacterota compared to PS group. A predictive metabolomics analysis recognized dTDP-L-rhamnose biosynthesis I in PS group as one of five unique pathways, while other five distinctive pathways, like peptidoglycan maturation, were linked to LDPE group. Further studies are needed to determine the plastic degrading properties of the detected bacteria. The results highlight T. molitor's versatility in biotechnological applications.

Fig. 1

(A) Relative abundance (%) of 10 top phylum taxa found in each midgut sample of T. molitor larvae fed with wheat bran (C-control group), those fed with wheat bran and polystyrene (PS group), and group feed with wheat bran and low-density polyethylene (LDPE group); (B) Heatmap showing the differential abundance of bacterial phyla in all three groups. The color key relates the heatmap colors to the standard score (z-score), i.e., the deviation from the row mean in units of standard deviation above or below the mean. Asterisks indicate significantly different group abundances (p < 0.05).

Fig. 2

Venn diagram representing shared and common OTUs. All abbreviations are the same as in Fig. 1.

Fig. 3

Alpha diversity indexes (A) Observed species, (B) Shannon index, (C) Chao1 index. Results are presented as mean ± SD, statistically significant at **p < 0.01. All abbreviations are the same as in Fig. 1.

Fig. 4

The 2D PCoA diagram based on the weighted (A) and unweighted (B) unifrac distance of bacterial communities. All abbreviations are the same as in Fig. 1.

Fig. 5

Linear discriminant analysis of effect size (LEfSe), based on OTUs at species level, and used to emphasize the differences between groups. All abbreviations are the same as in Fig. 1.

Fig. 6

PICRUSt prediction of functional abundances, presenting only pathways or enzymes that reached an LDA significance threshold of > 2. All abbreviations are the same as in Fig. 1.