Colon Flora, Microbiome
The colon can be compared to a septic tank, distinguished by its unpleasant contents: fermenting, putrefying food-waste. Enteros, the space inside the tube, remains "outside" the body. Trillions of microorganisms live in the colon. If the contents of the colon are spilled into the abdomen, thru a perforation, a life-threatening infection, peritonitis, ensues. The "septic" compartment is useful for the further degradation of undigested food and the liberation of additional nutrients. It is impossible to eliminate microorganism growth in the colon. All the people who seek colon cleanliness, with enemas, laxatives, purges and herbs are engaged in a futile and sometimes self-damaging exercise.
Tyler et al reviewed the investigation and appreciation of the human microbiome: "Over the past several years, a great deal of study has been directed toward evaluating the microbes living in or on the human host—the human microbiome. The human microbiome is defined as the collection of organisms and their genomes, inhabiting different anatomical locations both in and on humans. The gut alone is home to hundreds of trillions of microorganisms and contains more genetic information than that which exists in the human genome. Changes in human-associated microbial communities have been implicated in the etiology and increased incidence of several chronic conditions including obesity, diabetes, and inflammatory bowel disease (IBD)... The intestinal flora has also been implicated in the development of the immune system, being shown in several studies to have an important role in immune development... bacteria exist only rarely in isolation, and are instead most commonly found in complex community assemblages in which numerous different organisms share a similar ecological niche. In many cases, these organisms are co-dependent on one another, requiring metabolic support from additional members of the community for survival. In addition, organisms residing in or upon higher-order taxa must maintain a delicate balance with the host, in order to ensure that both symbionts flourish. In most cases, the relationship between such organisms is mutually beneficial: gut microbes, for example, help with the digestion of nutrients, prevent colonization of the host by pathogenic organisms, and aid in the proper development of both the intestinal epithelium and immune system, while the host provides nutrients and a suitable habitat for bacterial growth."
Marshall suggested: “The normal indigenous flora of the human gastrointestinal tract comprises a remarkably complex yet stable colonies, living in a symbiotic relationship with the human host. Stability of that flora is accomplished by multiple mechanisms including gastric acidity, gut motility, bile, products of immune cells in the gut epithelium, and competition between microorganisms for nutrients and intestinal binding sites. The indigenous flora influences multiple aspects of physiologic homeostasis and forms a key component of normal host defenses against infection by exogenous pathogens.”
Normark described the importance of the microbiome: “The intestinal tract contains the most densely colonised ecosystem of the human body, and it is this microbiome that has developed into a paradigm of beneficial interactions with its host. The major functions of the intestinal microbes have an impact on its holder in a variety of ways. The metabolic functions have a direct impact and include the conversion of non-digestible food components such as complex sugar polymers into short-chain fatty acids, the degradation of toxic compounds and the production of vitamins. However, the signaling functions of the intestinal microbiome and its products are increasingly recognized for their importance and modulate the host’s immune system or influence host development and physiology. This explains why deviations in the intestinal microbiome have been associated with dozens of diseases, varying from inflammatory bowel disease to type 2 diabetes and colorectal cancer. However, the complexity of the intestinal microbiome is unprecedented. Although over 1000 microbial, mostly bacterial and anaerobic, species have now been cultured from the human intestine, the majority of its microbial diversity has yet to be grown in pure culture. In addition, the intestinal microbiome is highly personalized and contains over 10 million genes. For simplicity and convenience, most studies have focused on the faecal microbiome, not taking into account the spatial organization of the intestinal communities, such as those associated with lumen, food particles or mucosa. Hence, intestinal biofilms have received only limited attention and if so mainly associated with disease. This is in contrast with some animal studies where biofilms are essential, such as in rodents that have a fore-stomach biofilm consisting of host-specific lactobacilli.”
The colon microbiota account for 1.5 kg of biomass. Every individual has ten-times more bacterial cells than human cells, conferring a different metabolic potential than the one encoded by the human genome. Therefore, from a metabolic point of view, it would be more correct to describe humans as 'superorganisms', that is, a human/microbes hybrid. Recent estimations suggest that there are approximately 15,000-36,000 different bacterial species forming the microbiota . One of its key features is the capacity to regenerate… the same populations emerge after a crisis such as antibiotic therapy."
The colon bacterial population is divided into two groups: aerobic and anaerobic bacteria. Bacteroides, lactobacilli, bifidobacteria and asaccharolytic produce lactic acid. Subgroups of anaerobic bateroides include: B. vulgatus, B. fragilis B. merdae/distasonis, B. ovatus, B. thetaiotaomicron B. uniformis, B. thetaiotaomicron.Moore suggested: “Fifteen bacterial taxa from the human fecal flora were significantly associated with high risk of colon cancer, and five were significantly associated with low risk of colon cancer. Total concentrations of Bacteroides species and, surprisingly, Bifidobacterium species were generally positively associated with increased risk of colon cancer. Some Lactobacillus species and Eubacterium aerofaciens, which also produces major amounts of lactic acid, showed closest associations with low risk of colon cancer.”
Colon bacteria feed mostly on undigested carbohydrate, and 99% of them survive best in the absence of oxygen (anaerobic bacteria). About 10-15% of starch from cereal grains, potatoes, and up to 50% of milk sugar in most adults enters the colon undigested where they are fermented by colon bacteria. CHO is transformed into short chain fatty acids and gas. Chapman suggested that: ” butyrate is a major energy source for the colonic epithelium and there may be a minor epithelial abnormality in the metabolism of butyrate in patients with ulcerative colitis. Immunological studies suggest that butyrate has an effect on lymphocyte activation and inhibits cell proliferation. An abnormal response to butyrate may upset the homeostasis between the gut immune system and the colonizing bacteria resulting in epithelial unrest and inflammation.”
Chien-Chang Chen et al. hypothesized that food sensitization (FS) in children could be linked to specific gut microbiota. The aim of their study was to quantify and evaluate differences in gut microbiota composition between children with FS and healthy controls. A case–control study of 23 children with FS and 22 healthy children was performed. Individual microbial diversity and composition were analyzed via parallel barcoded 454 pyrosequencing targeting the 16S rRNA gene hypervariable V3–V5 regions.Our results showed that FS is associated with compositional changes in the gut microbiota. These findings could be useful for developing strategies to control the development of FS or atopy by modifying the gut microbiota.
The children with FS exhibited lower diversity
of both the total microbiota (p = 0.01) and the bacterial phylum Bacteroidetes
(p = 0.02). In these children, the number of Bacteroidetes bacteria was
significantly decreased and that of Firmicutes were significantly increased
compared with the healthy children. At the genus level, we observed significant
increases in the numbers of Sphingomonas, Sutterella, Bifidobacterium,
Collinsella, Clostridium sensu stricto, Clostridium IV, Enterococcus,
Lactobacillus, Roseburia, Faecalibacterium, Ruminococcus, Subdoligranulum, and
Akkermansia in the FS group. We also found significant decreases in the numbers
of Bacteroides, Parabacteroides, Prevotella, Alistipes, Streptococcus, and
Veillonella in this group. Furthermore, linear discriminant analysis (LDA)
coupled with effect size measurements revealed the most differentially abundant
taxa (increased abundances of Clostridium IV and Subdoligranulum and decreased
abundances of Bacteroides and Veillonella), which could be used to identify FS. Chien-Chang Chen et al. Alterations in the gut microbiotas
of children with food sensitization in early life .
.Pediatric Allergy and Immunology published online: 21 JAN 2016)