Influence of feeding habit and duration on infant gut microbiome - a 6 month pilot study.

While the importance of breastfeeding on the developing infant gut microbiota has been established, few studies have compared the effect of breastfeeding duration on infant gut microbiota development. In this pilot study, we included 23 infants, divided into 4 groups to compare the effect of breastfeeding duration for first 4 (BreastFed_4) or 8 weeks (BreastFed_8) compared to exclusive breast (Exc Breast Fed) or formula feeding (Formula Fed) for 6 months. We used metagenomics shotgun sequencing of 88 infant stool samples and 64 corresponding maternal milk samples to examine the microbial composition. Breast milk samples showed the presence of previously defined core bacteria including spp. belonging to Staphylococcus, Streptococcus, Corynebacterium, Cutibacterium, Rothia and Pseudomonas. We report that the Exc Breast Fed infant group had the lowest alpha diversity and a distinct microbial composition compared to the Formula Fed group. BreastFed_4 clustered distinctly from all other groups, indicating the impact of duration and time of feeding on infant microbiota. Certain Bifidobacterium spp. were more associated to certain groups, in particular, B. infantis was more associated to Exc Breast Fed while Bacteroides/Phocaeicola with BreastFed_8. Exc Breast Fed showed the highest frequency of persisters with B. infantis being the dominant persister, while B. bifidum was the dominant persister in Formula Fed group. Persisters showed significantly higher abundance of several glycoside hydrolases (GH) important in early life across all groups compared to non-persisters. This study highlights infant gut microbiota changes associated with breastfeeding duration, warranting more detailed studies on the impact of breastfeeding duration on long-term health outcomes.