Microflora Research

In spite of the recent development of DNA based methods, microbiota development and characterization in the human host still rests largely on the culture-based assessment pioneered by Japanese researchers. The identification of different microbial species and strains has been dependent on microbial characterization, which is usually based on limited phenotypic properties and the metabolic activity of the microbes, for example, sugar fermentation profiles. There are several bacteria, however, that cannot be cultured and isolated or identified by the traditional methods. The culture technique as used in microbial assessments of feces is also hindered by the fact that microbes in the feces will mainly represent the microflora in the lumen of the sigmoid colon, while the composition of the intestinal microflora differs both along the GI tract and between the lumen and the mucosa. For more accurate information on the population elsewhere in the intestine, samples should be taken by endoscopy or during surgery. Most of our current data on microflora are derived from results obtained from fecal samples and culturing. These data indicate that there are several successive phases in microflora development related to age (Figure 1). In early infancy the microflora is scant and simple consisting mainly of bifido-bacteria. During breast-feeding it remains so, but following weaning its complexity increases, reaching the state observed in adults where the microflora is specific to each person. Aging is related to further changes and the diversity is again decreased. The microflora becomes more unstable and vulnerable to diseases, for example, diarrheal diseases caused by intestinal pathogens.

Current research efforts focus on revealing geno-mic data on both probiotic microorganisms and certain important intestinal commensals. This has

Infancy Adulthood Senescence

Figure 1 Development of microflora throughout life.

Infancy Adulthood Senescence

Figure 1 Development of microflora throughout life.

provided information indicating that gut commensals not only derive food and other benefits from the intestinal contents but also have a role in influencing the human host by providing maturational signals for the developing infant and child and providing later signals for alteration to gut barrier mechanisms.

The genomic data on, for instance, Bifidobacter-ium longum and Bacteroides thetaiotaomicron, both important members of the human intestinal microflora, give an indication as to how specific bacteria are adapted to the development of the gut by specific genes enabling the use of intestinal mucins and breast milk oligosaccharides as main sources or nutrients.

Genomic information on B. longum also gives insight into the adhesive mechanisms that comprise a basis both for populating the infant gut and for communicating developmental signals to specific areas and sites of the gut mucosa. Furthermore, a large part (>8.5%) of the B. longum genome is devoted to carbohydrate transport and metabolism, indicating a versatile metabolism well adapted to life in the intestine and making it very different from, for instance, Lactobacillus johnsonii.

Bacteroides thetaiotaomicron has also been shown to modulate glycosylation of the intestinal mucus and to induce expression of angiogenins, revealing proposed mechanisms whereby intestinal microbes may influence the gut microecology and shape the immune system. Incorporating such information with host gene expression data from the exposed mucosal sites and beyond them will enable us to understand the role of both microbial transfer and succession and microbe-microbe and host-microbe interactions. Recent information demonstrates that the vast community of indigenous microbes colonizing the human gut also shapes our development and biology.

New Mothers Guide to Breast Feeding

New Mothers Guide to Breast Feeding

For many years, scientists have been playing out the ingredients that make breast milk the perfect food for babies. They've discovered to day over 200 close compounds to fight infection, help the immune system mature, aid in digestion, and support brain growth - nature made properties that science simply cannot copy. The important long term benefits of breast feeding include reduced risk of asthma, allergies, obesity, and some forms of childhood cancer. The more that scientists continue to learn, the better breast milk looks.

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