Influence of selected dosages of plastic microparticles on the porcine fecal microbiome

Abstract

Studies conducted so far have shown that nano- and microplastic may disturb the intestinal microenvironment by interacting with the intestinal epithelium and the gut microbiota. Depending on the research model used, the effect on the microbiome is different-an increase or decrease in selected taxa resulting in the development of dysbiosis. Dysbiosis may be associated with intestinal inflammation, development of mental disorders or diabetes. The aim of the study was to analyze the intestinal microbiome in 15 gilts divided into 3 research groups (n = 5; control group, receiving micropartices at a dose 0.1 g/day (LD) and 1 g/day (HD)). Feaces were collected before and after 28 days of exposure to PET microplastics. The analysis of the intestinal microbiome was performed using next-generation sequencing. Alpha and beta diversity indices were compared, showing, that repetition affected only the abundance indices in the control and LD groups, but not in the HD group. The relationships between the number of reads at the phylum, genus and species level and the microplastic dose were calculated using statistical methods (r-Pearson correlation, generalized regression model, analysis of variance). The statistical analysis revealed, that populations of Family XIII AD3011 group, Coprococcus, V9D2013 group, UCG-010 and Sphaerochaeta increased with increasing MP-PET dose. The above-mentioned taxa are mainly responsible for the production of short-chain fatty acids (SCFA). It may be assumed, that SCFA are one of the mechanisms involved in the response to oral exposure to MP-PET.

Keywords: 16s rRNA; Metagenomics; Microplastic; Next-generation sequencing (NGS); Pig; Polyethylene terephthalate (PET).

Fig. 1

Alpha diversity in all experimental groups and body weight. Within sample diversity measured by (a) Observed, (b) ACE, (c) Chao1 (d) Shannon and (e) Simpson index. (f) Venna diagram shows the number of shared and individual OTUs in all groups. (g) Sum of counts of all and (h) unique ASV sequences in the study groups. (i) Gilts’ weight during the experiment. The gilts initial and final body weights were taken into account. C0—control group day 0, C28—control group day 28, LD0—low dose group day 0, LD28—low dose group day 28, HD0—high dose group day 0, HD28—high dose group day 28). Only statistically significant differences between the repetitions in groups C, LD and HD were included in the graph **p < 0.01, ***p < 0.001.

Fig. 2

The composition analysis of the microbiota community at the (a) phylum, (b) genus and (c) species level. The graphs show ten of the most numerous (a) phyla, (b) genera and (c) species. C0—control group day 0, C28—control group day 28, LD0—low dose group day 0, LD28—low dose group day 28, HD0—high dose group day 0, HD28—high dose group day 28.

Fig. 3

(a) r-Pearson correlation between the dose of MP-PET and (b) an analysis of variance for selected bacteria. (a) r-Pearson correlation between the dose of MP-PET and the number of readings at the level of phylum, genus and species. The calculated r values were interpreted as follows: 0–0.3 = weak positive/negative correlation (green); 0.3–0.5 = moderate positive/negative correlation (blue); 0.5–0.7 = strong positive/negative correlation (red); 0.7–1 = very strong positive/negative correlation (white). (b) An analysis of variance for selected bacteria (Mean ± SD), where statistically significant differences were demonstrated (p<0.05) in the number of readings depending on the MP-PET dose. C – control group, LD – low dose group, HD – high dose group.

Fig. 4

Characteristics of microplastic. (a, b) microscopic images, (c) particle size distribution and (d–f) SEM images of the polyethylene terephthalate.