Zinc Oxide Nanoparticles Influence Microflora in Ileal Digesta and Correlate Well with Blood Metabolites

Abstract

Zinc oxide nanoparticles (ZnO NPs) are used widely in consumer and industrial products, however, their influence on gut microbiota and metabolism and their mutual interactions are not fully understood. In this study, the effects of ZnO NPs on ileal bacterial communities, plasma metabolites, and correlations between them were investigated. Hens were fed with different concentrations of ZnO NPs [based on Zn; 0 mg/kg (control), 25 mg/kg, 50 mg/kg, and 100 mg/kg] for 9 weeks. Subsequently, ileal digesta and blood plasma were collected for analysis of microflora and metabolites, respectively. The V3-V4 region of the 16S rRNA gene of ileal digesta microbiota was sequenced using the Illumina HiSeq 2500 platform. The predominant bacterial community in the ileum belongs to the phylum Firmicutes. The richness of the bacterial community was negatively correlated with increasing amounts of ZnO NPs (r = -0.636, P < 0.01); when ZnO NP levels were at 100 mg/kg, microbiota diversity was significantly decreased (P < 0.05). The community structure determined by LEfSe analysis indicated that Bacilli, Fusobacteria, and Proteobacteria were changed, and Lactobacillus was reduced by ZnO NPs. Moreover, metabolism as analyzed by nuclear magnetic resonance (NMR) indicated that glucose, some amino acids, and other metabolites were changed by ZnO NPs. Choline, lactate, and methionine were positively correlated with bacterial richness. In summary, ZnO NPs could influence the levels of microflora in ileal digesta, particularly Lactobacillus. Furthermore, the richness of the microbiota was related to changes in choline, lactate, and methionine metabolism.

ZnO Modulates Swine Gut Microbiota and Improves Growth Performance of Nursery Pigs When Combined with Peptide Cocktail

“…In agreement with this, in vitro studies have shown that Lactobacillus acidophilus was impeded by ZnO nanoparticles (NPs) [68]. Some in vivo studies have also demonstrated that certain Lactobacillus species were reduced by dietary zinc in weaned piglets and chickens [50,69]. It may be that ZnO inhibited the Lactobacillus directly or promoted the growth of an antagonistic species against Lactobacillus within the gastrointestinal tract.…”

“…On the other hand, peptide with high-level zinc caused significant changes in growth performance and composition of the gut microbiota. Based on the lack of growth-promoting effects of ZnO on germ-free animals [48,49], we hypothesized that the beneficial effects of peptide + ZnO supplementation might be partly due to the distinguishable modulatory effect of ZnO on the gut microbiota and its metabolic regulatory function [50].…”

The gut microbiome and aquatic toxicology: An emerging concept for environmental health

“…In an in vivo study with zebrafish (Chen et al ), coexposure to nano‐TiO 2 and bisphenol A induced dysbiosis in the gut microbiome, and the nano‐TiO 2 exposure was associated with a significant increase in the relative abundance of Firmicutes and Bacteroidetes compared to controls. Feng et al () observed changes in gut microbiome structure and metabolic profiles in hens exposed to high concentrations of nano‐ZnO (>25 mg/kg), with notable impact on microbiome diversity at the highest treatment concentration, the relative abundance of several bacterial groups (class Bacilli and phyla Fusobacteria, Proteobacteria, and Firmicutes), and metabolite levels (most notably glucose, lactate, choline, and methionine) in treated hens compared to controls. An in vivo study conducted in piglets found that low levels of dietary nano‐Zn impacted the diversity and richness of the gut microbiome, with location‐specific alterations in the relative abundance of intestinal Firmicutes and Bacteroidetes (Xia et al ).…”

Pro-Inflammatory versus Immunomodulatory Effects of Silver Nanoparticles in the Lung: The Critical Role of Dose, Size and Surface Modification

“…The human lung microbiome harbors diverse microbial communities playing a critical role in immunomodulation as well as inflammation [ 17 , 18 ]. Although it has been proven in several studies that dietary nanoparticles severely influence the gut microflora [ 19 , 20 ], so far nothing is known about the effect of nanomaterials and their different physicochemical properties on the bacterial community composition of the lung; it’s likely that they affect the lung microbiome as well, with unknown consequences for human health.…”