Compositional Analysis Of The Bacterial Community In Colostrum Samples From Women With Gestational Diabetes Mellitus And Obesity

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Background. Obesity and Gestational Diabetes Mellitus (GDM) are major concerns during pregnancy as they compromise both mother and newborn health. These pathophysiology leads to variations in gut and breastmilk microbiota, threatening the settlement of neonate’s gut microbiota and the stimulation of immune cells. While several studies have described compositional changes of breast milk, placenta and maternal and newborn intestinal microbiota, it is unknown how breastmilk microbiota is affected under maternal GDM. The molecular mechanisms in which microbial-unbalanced breastmilk affect development of infants is not well understood for the case of obesity and GDM. As a first step, we used 16S- amplicon sequencing to describe the taxonomical bias of breastmilk of 43 women with GDM and women with obesity. We sampled colostrum within the first 24 h taken after birth in order to identify and quantify the first microbial community potentially colonizing infants gut.Results. A total of 1,675 amplicon sequence variants (ASVs) were identified, being Proteobacteria and Firmicutes the dominant phyla. We found Pseudomonas, Gemellales and Enterobacter overrepresented in samples of women with obesity and GDM. We used observed ASV´s, Shannon index and Faith´s phylogenetic diversity scores as alpha diversity indicators and UniFrac and robust Aitchison distances beta diversity indicators. Both metrics show a distinct microbial composition for GDM (female sub-group) and Obesity (male subgroup) compared to controls. Finally, differentially abundance analysis showed that Rhodococcaceae was distinct for GDM and 7 families (Bdellovibrionaceae, Burkholderiaceae, Halomonadaceae, Pseudomonadaceae, Shewanallaceae, TM7-1 and Vibrionaceae) with an absolute effect size greater than 1, of which 5 had a q-value ≤ 0.05 were distinct for obesity groups.Conclusions. To our knowledge, this study represents the first approach to the breastmilk bacteria composition of mothers with GDM. Our work provides the foundation for the design of functional metagnomic studies aiming to understand molecular mechanisms of which breastmilk from individuals with GDM and obesity affect the physiology of the infants.