Secretor Genotype (FUT2 gene) Is Strongly Associated with the Composition of Bifidobacteria in the Human Intestine

Intestinal microbiota plays an important role in human health, and its composition is determined by several factors, such as diet and host genotype. However, thus far it has remained unknown which host genes are determinants for the microbiota composition. We studied the diversity and abundance of dominant bacteria and bifidobacteria from the faecal samples of 71 healthy individuals. In this cohort, 14 were non-secretor individuals and the remainders were secretors. The secretor status is defined by the expression of the ABH and Lewis histo-blood group antigens in the intestinal mucus and other secretions. It is determined by fucosyltransferase 2 enzyme, encoded by the FUT2 gene. Non-functional enzyme resulting from a nonsense mutation in the FUT2 gene leads to the non-secretor phenotype. PCR-DGGE and qPCR methods were applied for the intestinal microbiota analysis. Principal component analysis of bifidobacterial DGGE profiles showed that the samples of non-secretor individuals formed a separate cluster within the secretor samples. Moreover, bifidobacterial diversity (p<0.0001), richness (p<0.0003), and abundance (p<0.05) were significantly reduced in the samples from the non-secretor individuals as compared with those from the secretor individuals. The non-secretor individuals lacked, or were rarely colonized by, several genotypes related to B. bifidum, B. adolescentis and B. catenulatum/pseudocatenulatum. In contrast to bifidobacteria, several bacterial genotypes were more common and the richness (p<0.04) of dominant bacteria as detected by PCR-DGGE was higher in the non-secretor individuals than in the secretor individuals. We showed that the diversity and composition of the human bifidobacterial population is strongly associated with the histo-blood group ABH secretor/non-secretor status, which consequently appears to be one of the host genetic determinants for the composition of the intestinal microbiota. This association can be explained by the difference between the secretor and non-secretor individuals in their expression of ABH and Lewis glycan epitopes in the mucosa

Metabonomics in neonatal and paediatric research: studying and modulating gut functional ecology for optimal growth and development

Gut microbiota play a fundamental role in human health by promoting intestinal homeostasis, stimulating development of the immune system, and providing protection against pathogens. Relatively little is known about the acquisition and development of this complex microbial community during infancy. However, emerging 'omics' technologies are now being applied to the study of the gut microbial ecology, generating new opportunities to deepen the functions of the gut microbiota in human health. All the published literature on paediatric and neonatal nutrimetabonomics is presented in a synthetic way, including studies on maternal milk and formula. The role of the disruption of the gut microbiota in various gastrointestinal diseases is considered, focusing the metabonomics approach in gut ischemia, chronic inflammatory diseases, cystic fibrosis, diabetes, and obesity. As a general rule, the best biofluid to study nutrition or to identify food-specific biomarkers is urine. In food consumption monitoring, the same concepts behind drug testing and drug monitoring can be used. In the opinion of the authors, in the near future improved tools for the analysis of the metabolic profile (simplified like 'dipsticks' for urine) and its integration with the other 'omics' data will move metabonomics beside the child, from top research to bedside

Toxins and their phytoremediation

The agricultural and industrial revolutions in the last few decades have resulted in increased concentration of toxins in our environment that are now-a-days a major cause of toxicity in plants and animals. Among different toxins, increasing levels of salts, heavy metal, pesticides and other chemicals are posing a threat to agricultural as well as natural ecosystems of the world. These contaminants result in soil, air and water pollution, and loss of arable lands as well as crop productivity. They also cause changes in species composition and loss of biodiversity by bringing about changes in the structure of natural communities and ecosystems. In this situation, different approaches are being adopted to reclaim polluted environments. Among these, phytoremediation has a potential in removing these toxins from the environment. This approach is based on the use of natural hyperaccumulator plant species that can tolerate relatively high levels of pollutants in the environment. Pollutants accumulated in stems and leaves of high biomass producing and tolerant plants can be harvested and removed from the site. Therefore, this approach has a potential to remove large amounts of toxins by harvesting the above-ground biomass. However, the effectiveness of phytoremediation approach can be increased if we have better knowledge of physiological, biochemical, molecular and genetic bases of plant resistance to natural and anthropogenic induced toxins. All these aspects of toxicity mechanisms and their removal techniques are comprehensively reviewed in this book. © Springer Science+Business Media B.V. 2010