Gut Microbiota from Twins Discordant for Obesity Modulate Metabolism in Mice
Establishing whether specific structural and functional configurations of a human gut microbiota are causally related to a given physiologic or disease phenotype is challenging. Twins discordant for obesity provide an opportunity to examine interrelations between obesity and its associated metabolic disorders, diet, and the gut microbiota. Transplanting the intact uncultured or cultured human fecal microbiota from each member of a discordant twin pair into separate groups of recipient germfree mice permits the donors’ communities to be replicated, differences between their properties to be identified, the impact of these differences on body composition and metabolic phenotypes to be discerned, and the effects of diet-by-microbiota interactions to be analyzed. In addition, cohousing coprophagic mice harboring transplanted microbiota from discordant pairs provides an opportunity to determine which bacterial taxa invade the gut communities of cage mates, how invasion correlates with host phenotypes, and how invasion and microbial niche are affected by human diets.
Separate groups of germfree mice were colonized with uncultured fecal microbiota from each member of four twin pairs discordant for obesity or with culture collections from an obese (Ob) or lean (Ln) co-twin. Animals were fed a mouse chow low in fat and rich in plant polysaccharides, or one of two diets reflecting the upper or lower tertiles of consumption of saturated fats and fruits and vegetables based on the U.S. National Health and Nutrition Examination Survey (NHANES). Ln or Ob mice were cohoused 5 days after colonization. Body composition changes were defined by quantitative magnetic resonance. Microbiota or microbiome structure, gene expression, and metabolism were assayed by 16S ribosomal RNA profiling, whole-community shotgun sequencing, RNA-sequencing, and mass spectrometry. Host gene expression and metabolism were also characterized.
Results and Discussion
The intact uncultured and culturable bacterial component of Ob co-twins’ fecal microbiota conveyed significantly greater increases in body mass and adiposity than those of Ln communities. Differences in body composition were correlated with differences in fermentation of short-chain fatty acids (increased in Ln), metabolism of branched-chain amino acids (increased in Ob), and microbial transformation of bile acid species (increased in Ln and correlated with down-regulation of host farnesoid X receptor signaling). Cohousing Ln and Ob mice prevented development of increased adiposity and body mass in Ob cage mates and transformed their microbiota’s metabolic profile to a leanlike state. Transformation correlated with invasion of members of Bacteroidales from Ln into Ob microbiota. Invasion and phenotypic rescue were diet-dependent and occurred with the diet representing the lower tertile of U.S. consumption of saturated fats, and upper tertile of fruits and vegetables, but not with the diet representing the upper tertile of saturated fats, and lower tertile of fruit and vegetable consumption. These results reveal that transmissible and modifiable interactions between diet and microbiota influence host biology.
Science 6 September 2013:
Vol. 341 no. 6150
The advancement of DNA/RNA, proteins, and metabolite analytical platforms, combined with increased computing technologies, has transformed the field of microbial community analysis. This transformation is evident by the exponential increase in the number of publications describing the composition and structure, and sometimes function, of the microbial communities inhabiting the human body. This rapid evolution of the field has been accompanied by confusion in the vocabulary used to describe different aspects of these communities and their environments. The misuse of terms such as microbiome, microbiota, metabolomic, and metagenome and metagenomics among others has contributed to misunderstanding of many study results by the scientific community and the general public alike. A few review articles have previously defined those terms, but mainly as sidebars, and no clear definitions or use cases have been published. In this editorial, we aim to propose clear definitions of each of these terms, which we would implore scientists in the field to adopt and perfect.
Americans spend the vast majority of their lives in built environments. Even traditionally outdoor pursuits, such as exercising, are often now performed indoors. Bacteria that colonize these indoor ecosystems are primarily derived from the human microbiome. The modes of human interaction with indoor surfaces and the physical conditions associated with each surface type determine the steady-state ecology of the microbial community.
Bacterial assemblages associated with different surfaces in three athletic facilities, including floors, mats, benches, free weights, and elliptical handles, were sampled every other hour (8 am to 6 pm) for 2 days. Surface and equipment type had a stronger influence on bacterial community composition than the facility in which they were housed. Surfaces that were primarily in contact with human skin exhibited highly dynamic bacterial community composition and non-random co-occurrence patterns, suggesting that different host microbiomes—shaped by selective forces—were being deposited on these surfaces through time. However, bacterial assemblages found on the floors and mats changed less over time, and species co-occurrence patterns appeared random, suggesting more neutral community assembly.
These longitudinal patterns highlight the dramatic turnover of microbial communities on surfaces in regular contact with human skin. By uncovering these longitudinal patterns, this study promotes a better understanding of microbe-human interactions within the built environment.
Depending on who is doing the eating, living off nothing but burgers and McNuggets has wildly different outcomes.
Just when McDonald’s thought it may have found its very own Jared Fogle—the “Subway Guy”—to prove you can go on a steady diet of Mickey D’s and still be healthy, here comes news that eating too many Big Macs may be more like declaring war on the good bacteria in your gut.
Ever since the phenomenon of the popular documentary Super Size Me more than a decade ago, plenty of Internet memes surrounding the question of “What crazy things happen to your body when you eat a ton of McDonald’s?” have been spawned. The sheer ubiquity of the once indomitable fast-food chain swiftly made it the lumbering target for everything that’s gone wrong with how we eat, and thus, the prime culprit behind Americans’ ever-expanding waistlines and related health issues.
But last year, a high school science teacher from Iowa became a viral sensation by touting an all-McDonald’s diet that allowed him to shed more than 60 pounds in six months. It started as a class project: John Cisna challenged his students to come up with a diet consisting entirely of food from McDonald’s yet still within the federal government’s 2,000-calorie-a-day guideline for adults, and he gamely became the class guinea pig.
Dynamic changes in short- and long-term bacterial composition following fecal microbiota transplantation for recurrent Clostridium difficile infection
Alexa Weingarden1,7†, Antonio González2, Yoshiki Vázquez-Baeza3†, Sophie Weiss4, Gregory Humphry5, Donna Berg-Lyons5, Dan Knights6,7, Tatsuya Unno7, Aleh Bobr8, Johnthomas Kang7,8, Alexander Khoruts7,8, Rob Knight2,9,10 and Michael J Sadowsky1,7*
Background: Fecal microbiota transplantation (FMT) is an effective treatment for recurrent Clostridium difficile infection (CDI) that often fails standard antibiotic therapy. Despite its widespread recent use, however, little is known about the stability of the fecal microbiota following FMT.
Results: Here we report on short- and long-term changes and provide kinetic visualization of fecal microbiota composition in patients with multiply recurrent CDI that were refractory to antibiotic therapy and treated using FMT. Fecal samples were collected from four patients before and up to 151 days after FMT, with daily collections until 28 days and weekly collections until 84 days post-FMT. The composition of fecal bacteria was characterized using high throughput 16S rRNA gene sequence analysis, compared to microbiota across body sites in the Human Microbiome Project (HMP) database, and visualized in a movie-like, kinetic format. FMT resulted in rapid normalization of bacterial fecal sample composition from a markedly dysbiotic state to one representative of normal fecal microbiota. While the microbiome appeared most similar to the donor implant material 1 day post-FMT, the composition diverged variably at later time points. The donor microbiota composition also varied over time. However, both post-FMT and donor samples remained within the larger cloud of fecal microbiota characterized as healthy by the HMP.
Conclusions: Dynamic behavior is an intrinsic property of normal fecal microbiota and should be accounted for in comparing microbial communities among normal individuals and those with disease states. This also suggests that more frequent sample analyses are needed in order to properly assess success of FMT procedures.
Keywords: Short- and long-term changes in microbiota following FMT
- Received 25 September 2014, Revised 16 December 2014, Accepted 18 February 2015, Available online 9 April 2015
- Published: April 9, 2015
- •Gut microbes regulate levels of 5-HT in the colon and blood
- •Spore-forming bacteria modulate metabolites that promote colon 5-HT biosynthesis
- •Microbiota-dependent changes in 5-HT impact GI motility and hemostasis
- •Altering the microbiota could improve 5-HT-related disease symptoms
The gastrointestinal (GI) tract contains much of the body’s serotonin (5-hydroxytryptamine, 5-HT), but mechanisms controlling the metabolism of gut-derived 5-HT remain unclear. Here, we demonstrate that the microbiota plays a critical role in regulating host 5-HT. Indigenous spore-forming bacteria (Sp) from the mouse and human microbiota promote 5-HT biosynthesis from colonic enterochromaffin cells (ECs), which supply 5-HT to the mucosa, lumen, and circulating platelets. Importantly, microbiota-dependent effects on gut 5-HT significantly impact host physiology, modulating GI motility and platelet function. We identify select fecal metabolites that are increased by Sp and that elevate 5-HT in chromaffin cell cultures, suggesting direct metabolic signaling of gut microbes to ECs. Furthermore, elevating luminal concentrations of particular microbial metabolites increases colonic and blood 5-HT in germ-free mice. Altogether, these findings demonstrate that Sp are important modulators of host 5-HT and further highlight a key role for host-microbiota interactions in regulating fundamental 5-HT-related biological processes.
Right after birth, trillions of microbes rush into a baby’s gut and start to grow. Most of these critters come from the mom’s skin, birth canal and gut.
But exactly which types of bacteria take up residence in an infant’s gut can depend on the mother’s DNA, scientists reported Thursday.
The study, published in the journal Microbiome, focuses on a microbe called Bifidobacterium that potentially benefits babies.
“It plays a role in preventing infections,” says Zachery Lewis, a graduate student in microbiology at the University of California, Davis, who contributed to the study. “Bifidobacteria sort of push other bacteria out. They lower the gut’s pH, which a lot of pathogens don’t like.”
After birth, Bifidobacterium is one of the first microbes to arrive in a baby’s gut. But not all infants get the microbe at the same time — or in the same amounts.
Microbiome Restoration Comment – Mom’s DNA Alters Baby’s Gut Bacteria
Great article. Encouraging mothers to breast feed is very important. From the minute an infant leaves the safety of its mother’s womb it now has to fend for itself. Breast milk is key to the beginning of a healthy microbiome.
Above images source – microbewiki.kenyon.edu
The Lactobacillus bacterium, stained blue here, colonizes the human gut when people eat yogurt. A new study details how L. rahmnosus, a single-organism probiotic, helps the gut microbiome flourish.
Microbiome Restoration Editors note –
While it may seem that certain bacteria may not produce any exotic or powerful compounds that the body uses directly, it now appears that certain probiotic bacteria act as “traffic cops” or regulators of the other bacteria. It is likely that these are as important as the bacteria that directly produce helpful compounds.
Lactobacillus, also called Döderlein’s bacillus, is a genus of Gram-positive facultative anaerobic or microaerophilic rod-shaped bacteria. They are a major part of the lactic acid bacteria group, named as such because most of its members convert lactose and other sugars to lactic acid. In humans they are present in the vagina and the gastrointestinal tract, where they make up a small portion of the gut flora. They are usually benign, except in the mouth where they have been associated with cavities and tooth decay (dental caries). Many species are prominent in decaying plant material. The production of lactic acid makes its environment acidic, which inhibits the growth of some harmful bacteria. Several members of the genus have had their genome sequenced.
Source – Wikipedia
Lactobacillus reuteri are Gram-positive, rod-shaped, and anaerobic. These heterofermentatic lactic acid bacterium naturally inhabit the gut of a wide range of organisms, including humans, pigs, chickens and mice . They can also be isolated from human breast milk . In vitro, Lactobacillus reuteri grows optimally on MRS media at 37 degrees Celsius . They have also been found to grow in biofilms . The Food and Agricultural Organization of the United Nations describes probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit on the host,”  an idea first vocalized by Elie Metchnikoff, in the early 1900’s . L. reuteri produces reuterin, an antimicrobial that inhibits growth of harmful bacteria, fungi, and protozoa. Due to these probiotic properties, L. reuteri is believed to be a promising therapy for the alleviation and reduction of certain illnesses related to gastrointestinal health, oral health, and urogenital health, including infantile colic, eczema, and H. pylori infection .
Source – microbewiki.kenyon.edu