Some Facts about the Friendly and Not-So-Friendly Microbes that Live On and Within Us

May 04, 2015

Some Facts about the Friendly and Not-So-Friendly Microbes that Live On and Within Us

Trillions of microorganisms inhabit us -- inside and out with recent estimates reaching four pounds of biomass or roughly over 200 trillion microorganisms.
They reside on our skin and in our mouth, by our eyelids, in our stomach and intestines, in the vagina, and in the milk ducts of the breasts. They have even been discovered comfortably residing in our respiratory tract. Scientists are surveying these microbial cities to learn more about their role in health.

Microbiologists Darren Sledjeski of the National Institutes of Health (NIH) and Andrew Goodman of Yale University share a few details of what researchers have learned so far.
1. The majority of the microbes that inhabit us are bacteria. The rest of the microbial stew is fungi and viruses, including some that infect our bacteria. Collectively, our resident microorganisms are referred to as the human microbiota, and their genomes are called the human microbiome.
2. Our bodies harbor more bacterial cells than human cells. Even so, the microbiota accounts for less than 3 percent of a person's body mass. That's because our cells are up to 10,000 times bigger in volume than bacterial cells.
3. Your collection of bacteria has more genes than you do. Scientists estimate that the genomes of gut bacteria contain 100 times as many genes as our own human genome. For this reason, the human microbiome is sometimes called our second genome.
4. Most of our microbes are harmless, and some are helpful. For example, harmless microbes on the skin keep infectious microbes from occupying that space. Microbes in the colon break down lactose and other complex carbohydrates that our bodies can't naturally digest.
5. Different microbes occupy different parts of the body. Some skin bacteria prefer the oily nooks near the nose, while others like the dry terrain of the forearm. Bacteria don't all fare well in the same environment and have adapted to live in certain niches.
6. Each person's microbiota is unique. The demographics of microbiota differ among individuals. Diet is one reason. Also, while a type of microbe might be part of one person's normal microbial flora, it might not be part of another's, and could potentially make that person sick.
7. Host-microbial interactions are universal. Microbial communities may vary from person to person, but everyone's got them, including other creatures. For this reason, researchers can use model organisms to tease apart the complexities of host-microbial interactions and develop broad principles for understanding them. The mouse is the most widely used animal model for microbiome studies.
8. The role of microbiota in our health isn't entirely clear. While it's now well accepted that the microbial communities that inhabit us are actively involved in a range of conditions -- from asthma to obesity -- research studies have not yet pinpointed why or how. In other words, the results may suggest that the presence of a bacterial community is associated with a disease, but they don't show cause and effect.
9. Most of our microbes have not been grown in the lab. Microbes require a certain mix of nutrients and other microbes to survive, making it challenging to replicate their natural environments in a petri dish. New culturing techniques are enabling scientists to study previously uncultivated microbes.

The above information is based on data from the NIH, National Institute of General Medical Sciences (NIGMS). Note: Materials may be edited for content and length

Note; the bacteria in our intestines are the microbiota and are sometimes referred to as our flora. A supplement of healthy bacteria to support good digestion and health is a Probiotic supplement. CFU means the bacteria are alive and are more likely to successfully form colonies (CFU stands for colony forming units).

Additional data from other sources;
> Promoting healthy gut bacteria can help protect us from heart disease, diabetes and stroke; Georgia State University and Cornell University in the journal Gastroenterology
> A change of bacteria from good to bad (dysbiosis) is connected to breast cancer; Don Monti Division of Oncology, Hofstra North Shore Long Island Jewish School of Medicine in the journal ISRN Oncology
> Certain Probiotics can help women lose weight; Laval University in the British Journal of Nutrition
> Probiotic bacteria may treat vaginal yeast infections; University Hospital in Perugia in the Journal of Applied Microbiology
> Probiotic bacteria may reduce the risk of recurrent urinary tract infections; University of Washington in Seattle in the journal Clinical Infectious Diseases
> Probiotic bacteria improve the immune system of elderly people within three weeks; University of Reading in the Journal of Nutritional Science
> Regularly taking probiotics improves your blood pressure; School of Medicine at Griffith University published in the journal Hypertension
> Probiotic supplements reduce the number of colds and number of days with symptoms or days missed from daycare, school or work in children and adults; York Health Economics Consortium in the UK and Dairy and Food Culture Technologies in California in the British Journal of Nutrition
> A review of existing studies show that probiotics may help reduce fat in the liver in patients with non-alcoholic fatty liver disease (NAFLD); Omega Research Team USA in the Journal of Functional Foods
> Probiotic help remove mercury from our body; Western Ontario University in the journal mBio.
> A) Our Western lifestyle B) our diet C) and stress all kill off our friendly bacteria; A) University of Alberta in Canada in the journal Cell Reports B) University of California San Francisco in the journal Cell Host and Microbe C) Ohio State University and Texas Tech University Health Sciences Center published in the journal Brain, Behavior, and Immunity