In this review, we aim to discuss current knowledge of intestinal (butyrate-producing) microbiota composition in obesity as well as the use of faecal transplantation using different donors to mine for beneficial intestinal bacterial strains to treat obesity and subsequent type 2 diabetes mellitus. The intestinal microbiota of the newborn human was thought to be essentially sterile, but recent data suggest that modest bacterial translocation via placental circulation antenatally is likely to provide a primitive bacterial

community to the meconium [8]. Although the new concept of fetal intestinal colonization remains controversial, recent ongoing studies using 16S rRNA gene pyrosequencing to characterize the bacterial population in meconium of preterm infants suggest that the bacteria of maternal intestine are able to cross the AZD1208 cell line placental barrier and act as

the initial inoculum for the fetal gut microbiota [8, Tanespimycin 9]. Nevertheless, the infant’s gut is only colonized fully by maternal and environmental bacteria during birth. Whereas the vaginally delivered infant’s intestinal microbial communities resemble their own mother’s vaginal microbiota (dominated by Lactobacillus, Prevotella or Sneathia spp.), newborns delivered by caesarean section harbour intestinal bacterial societies similar to those found on maternal skin surface, dominated by Staphylococcus, Corynebacterium and Propionibacterium spp. [9]. In this regard, it is interesting to note that mode of delivery (caesarean) is associated with increased risk of obesity later in life [10]. Other than the delivery mode, gestational age

at birth, diet composition and antibiotic use by the infant may have significant impacts to determine the composition of the infant’s intestinal microbial communities and body mass index (BMI) [11]. With respect to feeding pattern, the composition of intestinal bacteria differs substantially between breast-fed and formula-fed infants, which is thought to be due to the breast milk containing (prebiotic) oligosaccharides [12, 13]. The subsequent transformation of the intestinal microbiota from infant- to adult-type is triggered via bidirectional cross-talk between 17-DMAG (Alvespimycin) HCl host and predominantly dietary and environmental factors [12, 14], but remains relatively stable until the 7th decade of life [15]. It is thus likely that host (immunological) responses to inhabitant commensal bacteria differ from those elicited towards pathogens that do not belong to the indigenous microbiota [16, 17]. The precise mechanisms of how intestinal microbes affect and protect host immune physiology, however, are yet to be revealed. There is now solid evidence that composition of the intestinal microbiota is altered in obese people on a western diet compared to lean [18, 19]. Moreover, dietary composition seems to be one the most important determinants of intestinal microbiota diversity driving obesity [20, 21].