Abstract
The early-life microbiota triggers life-long effects on physiological functions and health disorders. Previous studies in adult twins or animal models have revealed associations between host genetics and the harmonious microbiota. However, such associations may be obscured by the fact that each intra-pair of twins will continually encounter various environmental factors as they grow up. Here, we collected the meconium samples from nineteen dizygotic pairs (DZ, n = 38) and nine monozygotic pairs (MZ, n = 18) with cesarean delivery, and 16S rRNA gene sequencing was performed to profile the microbiome at birth. Diversity analysis showed that alpha diversity was not significantly different between two groups, whereas beta diversity of MZ twins was significantly lower than that of either DZ twins or unrelated individuals (i.e., randomly selected individual pairs of non-twinship) (p < 0.05). Two groups had very similar microbial classifications but different relative abundances of certain taxa including more Firmicutes (p = 0.05, Wilcoxon test) at the phylum level and lower abundances of five genera (p < 0.05) in DZ group compared to MZ group, including Rheinheimera, Proteus, SMB53, Sphingobium, and Megamonas. Co-occurrence analysis in each group showed slightly more complicated microbial interactions in DZ than MZ twins, although 22 shared bacterial genera co-existed in two groups, with both Rheinheimera and Megamonas having different centralities in their respective co-occurrence networks. Mean intra-class correlation coefficient (ICC) were also significantly higher for MZ (0.312) compared to DZ twins (0.138) (p < 0.05). The predicted microbial gene functions related to carbohydrate were higher in DZ group, whereas folding, sorting, degradation, cell motility pathways and energy metabolism were markedly over-represented in the microbiota of MZ group. In summary, our study uncovered that microbial diversity and components of the meconium microbiome between DZ and MZ twins were partially consistent with that in singleton neonates by cesarean delivery, but several distinctions related to the heritability supported genetic contributions to intestinal microbiome in early life.
Highlights
Growing studies have documented microbiota of newborn meconium which influenced immune and metabolic development in early-life and might, have short and long-term health consequences (Marie-Claire et al, 2014; Tamburini et al, 2016; Milani et al, 2017)
Our study reported the inter-characteristics and intra-traits of meconium microbiome in different chorionic twin pregnancies evaluated by microbial diversity, taxa abundance, individual microbial components and bacterial interactions
This study provided landscape of meconium microbiomein both MZ and DZ twins born by caesarean section (CS)
Summary
Growing studies have documented microbiota of newborn meconium which influenced immune and metabolic development in early-life and might, have short and long-term health consequences (Marie-Claire et al, 2014; Tamburini et al, 2016; Milani et al, 2017). Based on results from large-scale human population and mouse studies under controlled conditions, genetics is an indispensable shaper of microbial diversity and composition related to diet, innate immunity, and energy metabolism etc. It is urgent to better explore how genetics factors contribute to early-life microbiome composition. Twins, with their high genetic and environmental resemblance, are well appropriate for probing the role of the gut microbiome and clarifying gene-environment effects on complex phenotypes. If host genetics may conceivably influence a particular microbiological phenotype, there are more similar phenotype within MZ compared to within DZ twins
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