What bacteria live in the gym?

A lot of research goes into understanding the complexity and dynamics of the human microbiome in the GI tract or the mouth, to name a few locations. In an article published by Microbiome, researchers at Northwestern University took a different perspective in that they looked at how the human microbiome affects the environments around us. A very interesting point raised by the article is that Americans spend most of their time in so-called “built environments,” which are indoors. The microbes of these indoor environments are mainly affected by the humans that interact with them, so the scientists at Northwestern University took to studying how the bacterial composition of indoor athletic equipment and facilities are affected. This specific environment was chosen mainly because of the numerous different human encounters it experiences.

For 2 days, the researchers collected swab samples in 3 athletic facilities. Samples were collected every 2 hours from the floor, mats, elliptical handles, free weights, and benches from 8 am to 6 pm, and a total of 356 samples were collected.  After sequencing and analysis, the researchers concluded that, consistent with all three facilities, the bacteria found on the equipment was most likely to be from the human skin, with Pseudomonas and Acinetobacter showing up in the most samples. Besides microbiota from the skin, other bacteria were found to be abundant such as Bacteroides from the human intestinal tract on elliptical handles and Finegoldia, also from the GI tract, on benches.

As for which sampled location had the most stable bacterial community, it was found that the floor and mats showed the least change in structure. This is most likely because elliptical handles, free weights, and benches come in more direct contact with human skin. Across the board, the only genera which were found in all samples from every surface type were Staphylococcus and Pseudomonas. It is important to remember that none of this means athletic facilities are blooming with harmful bacteria, and we should stay far away. In fact, the environment is not very conducive to the thriving of bacteria, because it lacks a lot of resources. What we should take away from this study is that any surface that comes in contact with human skin is likely to reflect the microbiome of that person. 

Microbiome influenced by forced versus voluntary exercise in mice

A team of scientists led by researchers at the Mayo Clinic recently discovered that forcing mice to exercise led to exacerbated inflammation, whereas allowing the mice to exercise voluntarily attenuated inflammation.  They hypothesized that the gut microbiome may be responsible for this rather peculiar phenomenon, so they repeated the study, this time measuring changes in the microbiome.  They published their results in the Journal of Applied Physiology.

The scientists separated 29 mice into three groups, a group that was forced to exercise for 40 minutes per day, a group that voluntarily exercised, and a sedentary group that did not exercise.  They conducted their study over 6 weeks, after which the mice were euthanized and their microbiomes sampled.  The researchers discovered that even though each of the groups gained approximately 10% body weight over the course of the study, their microbiomes deviated.  Interestingly, the mice that voluntarily exercised, those same mice that attenuated inflammation, had the lowest gut microbiome diversity (a trait normally related to dysbiosis and illness).  On the genus level, Mollicutes, which has been associated with ulcerative colitis, and Nauatilia were elevated in the feces of mice forced to exercise.  In addition, Turicibacter, which is related to various organisms associated with IBD, was actually decreased in the mice that voluntarily exercised.  Beyond these loose associations though, the exercise’s impact on the microbiome was not clear.

Exercise can change the microbiome, and the authors suggest that the total amount of exercise between the voluntary and forced exercise groups may have been important, as it was not controlled in this study.  Strangely, in humans, excessive exercise and no exercise at all have both been linked to gastrointestinal issues like diarrhea and constipation.  Unfortunately, the authors did not study whether the mouse version of Jillian Michaels trainers constituted forced, or voluntary exercise. 

New evidence for the relationship between obesity and the microbiome

Obesity is rapidly becoming a big problem in the United States (no pun intended), and up to one-third of adults are obese, according to the Centers for Disease Control and Prevention. As a disease, obesity is not well understood because there are so many factors that are involved in weight control, including caloric intake, genetic predisposition, and psychological factors among many others. A study done by researchers at the Institute of Nutritional Sciences, of the University of Vienna, and recently published by Beneficial Microbes, considers another factor involved in obesity: the microbiome.  Previous research on mice has shown that the microbiome is associated with obesity and leanness, and that diet can be an important tool to modulate it.  These researchers extended some of these ideas to humans, and studied the microbiomes of obese people as they lost weight through diet and exercise.

The researchers studied 33 obese participants during a four month period of strict diet and exercise regime, which resulted in weight loss. Fecal samples were collected once before, during, and after the study and the bacterial content was tested.

A decisive difference in the bacterial content of the gut was found in individuals before the study and after weight loss. Significant findings of this study include the increased presence of Lactobacilli after weight loss, a genera that has been found to have probiotic, anti-inflammatory characteristics.  The study also found that weight loss was associated with a decrease in the ratio of Firmicutes to Bacteroidetes, with the abundance of Firmicutes increasing in presence and the abundance of Bacteroidetes remaining the same.  Interestingly, the amount of weight lost was related to the amount decrease in this ratio.  Finally, the scientists found that Archaea, which are a distinct phylogenetic domain from Bacteria and Eukaryotes, increased in abundance after weight loss.

As we know, the microbiome holds a lot of promise in the fight against obesity, and this study, as well as those that are sure to follow, could impact obesity treatments in the future.  We need to remember, though, that far more rigorous studies are needed before any actionable strategies to modulate the microbiome to lose weight are established.  Perhaps though, the key to achieving a healthy weight is to maintain a certain level of bacterial diversity in the gut.

Exercise and the microbiome

A few months ago an article was published in the journal Gut that investigated the connection between the microbiome and exercise.  In the study, 40 elite rugby players and 46 healthy men who were not professional athletes with similar body mass indexes from Ireland were studied.  Stool and blood samples were taken from each person, as well as a survey on their exercise and eating habits.

The scientists discovered that:

1) Blood samples showed that athletes had lower inflammatory markers relative to the non-athletes.
2) Athletes had a higher diversity of gut microbiota than non-athletes.
3) Several specific taxa were abundant in the athletes' guts, including Akkermansia, which has been implicated in gut health in mice.
4) Exercise and consumption of protein was associated with greater gut microbiome diversity.

This is a very interesting study, and one of the first that makes a connection between exercise and biodiversity.