Human gut microbiota directly influences health and provides an extra means of adaptive potential to different lifestyles. To explore variation in gut microbiota and to understand how these bacteria may have co-evolved with humans, here we investigate the phylogenetic diversity and metabolite production of the gut microbiota from a community of human hunter-gatherers, the Hadza of Tanzania. We show that the Hadza have higher levels of microbial richness and biodiversity than Italian urban controls. Further comparisons with two rural farming African groups illustrate other features unique to Hadza that can be linked to a foraging lifestyle. These include absence of Bifidobacterium and differences in microbial composition between the sexes that probably reflect sexual division of labour. Furthermore, enrichment in Prevotella, Treponema and unclassified Bacteroidetes, as well as a peculiar arrangement of Clostridiales taxa, may enhance the Hadza’s ability to digest and extract valuable nutrition from fibrous plant foods.

Altogether, our results indicate that both a peculiar dysbiosis of the gut microbiota and a significant decrease of butyrate production are present in patients with Behçet syndrome.

Acute GvHD (aGvHD) is the main complication of hematopoietic SCT (HSCT) during the treatment of hematological disorders. We carried out the first longitudinal study to follow the gut microbiota trajectory, from both the phylogenetic and functional points of view, in pediatric patients undergoing HSCT. Gut microbiota trajectories and short-chain fatty acid production profiles were followed starting from before HSCT and through the 3-4 months after transplant in children developing and not developing aGvHD. According to our findings, HSCT procedures temporarily cause a structural and functional disruption of the gut microbial ecosystem, describing a trajectory of recovery during the following 100 days. The onset of aGvHD is associated with specific gut microbiota signatures both along the course of gut microbiota reconstruction immediately after transplant and, most interestingly, prior to HSCT. Indeed, in pre-HSCT samples, non-aGvHD patients showed higher abundances of propionate-producing Bacteroidetes, highly adaptable microbiome mutualists that showed to persist during the HSCT-induced ecosystem disruption. Our data indicate that structure and temporal dynamics of the gut microbial ecosystem can be a relevant factor for the success of HSCT and opens the perspective to the manipulation of the pre-HSCT gut microbiota configuration to favor mutualistic persisters with immunomodulatory properties in the gut.Bone Marrow Transplantation (2015) 50, 992-998;

Aims:  This study was undertaken to evaluate the oxalate‐degrading activity in several Lactobacillus species widely used in probiotic dairy and pharmaceutical preparations. Functional characterization of oxalyl‐CoA decarboxylase and formyl‐CoA transferase in Lactobacillus acidophilus was performed in order to assess the possible contribution of Lactobacillus in regulating the intestinal oxalate homeostasis. Methods and Results:  In order to determine the oxalate‐degrading ability in 60 Lactobacillus strains belonging to 12 species, a screening was carried out by using an enzymatic assay. A high variability in the oxalate‐degrading capacity was found in the different species. Strains of Lact. acidophilus and Lactobacillus gasseri showed the highest oxalate‐degrading activity. Oxalyl‐CoA decarboxylase and formyl‐CoA transferase genes from Lact. acidophilus LA14 were cloned and sequenced. The activity of the recombinant enzymes was assessed by capillary electrophoresis. Conclusions:  Strains of Lactobacillus with a high oxalate‐degrading activity were identified. The function and significance of Lact. acidophilus LA14 oxalyl‐CoA decarboxylase and formyl‐CoA transferase in oxalate catabolism were demonstrated. These results suggest the potential use of Lactobacillus strains for the degradation of oxalate in the human gut. Significance and Impact of the Study:  Identification of probiotic strains with oxalate‐degrading activity can offer the opportunity to provide this capacity to individuals suffering from an increased body burden of oxalate and oxalate‐associated disorders.

Oxalic acid occurs extensively in nature and plays diverse roles, especially in pathological processes. Due to its highly oxidizing effects, hyperabsorption or abnormal synthesis of oxalate can cause serious acute disorders in mammals and can be lethal in extreme cases. Intestinal oxalate-degrading bacteria could therefore be pivotal in maintaining oxalate homeostasis and reducing the risk of kidney stone development. In this study, the oxalate-degrading activities of 14 bifidobacterial strains were measured by a capillary electrophoresis technique. The oxc gene, encoding oxalyl-coenzyme A (CoA) decarboxylase, a key enzyme in oxalate catabolism, was isolated by probing a genomic library of Bifidobacterium animalis subsp. lactis BI07, which was one of the most active strains in the preliminary screening. The genetic and transcriptional organization of oxc flanking regions was determined, unraveling the presence of two other independently transcribed open reading frames, potentially responsible for the ability of B. animalis subsp. lactis to degrade oxalate. pH-controlled batch fermentations revealed that acidic conditions were a prerequisite for a significant oxalate degradation rate, which dramatically increased in cells first adapted to subinhibitory concentrations of oxalate and then exposed to pH 4.5. Oxalate-preadapted cells also showed a strong induction of the genes potentially involved in oxalate catabolism, as demonstrated by a transcriptional analysis using quantitative real-time reverse transcription-PCR. These findings provide new insights into the characterization of oxalate-degrading probiotic bacteria and may support the use of B. animalis subsp. lactis as a promising adjunct for the prophylaxis and management of oxalate-related kidney disease.Oxalate is a normal end product of amino acid metabolism and must be excreted, predominantly via the kidney, to maintain homeostasis (22). Oxalate is also present in a wide range of foods and drinks, and the normal dietary intake is variable, ranging from 70 to 920 mg per day (23). Because of its highly oxidizing effects and the capability to combine with cations to form insoluble salts, this organic dicarboxylate is extremely toxic for most forms of life. In humans, oxalate can cause a variety of pathological disorders, including hyperoxaluria, urolithiasis, cardiomyopathy, and renal failure (29,41,59). Hyperoxaluria is the single strongest promoter of kidney stone formation, whose medical management represents a burden to the individual patient as well as the health care system (49). The lack of new medications and the continued poor compliance with drug therapy have led to a growing interest in dietary manipulation and novel therapies aimed at preventing recurrent stone formation. Unfortunately, an oxalate-free diet is difficult to achieve and would probably be deficient in essential nutrients. Hence, other approaches to reducing urinary oxalate for management of stone disease have been explored.The discovery of oxalate-degrading bacteria within the human ...