Are Certain Bacteria Associated With Development of Colorectal Cancer?

The gut microbiome may play an important role in the development of colorectal cancer, according to a study published in the Journal of Gastrointestinal Oncology. Study author Jessica D. Dahmus, MD, of the Thomas Jefferson University Hospital, and colleagues sought to analyze the potential carcinogenic associations of five strains of sulfidogenic bacteria based on prior published research.

Sulfidogenic bacteria was focused on due to its production of hydrogen sulfide, which has been shown to cause DNA damage. This can result in genomic instability, notably found in more than 80% of sporadic colorectal cancers. The authors suggested that hydrogen sulfide affects mitochondrial function in intestinal epithelial cells, resulting in hyperproliferation in the Ras/MAPK pathway. Colorectal cancer is one of many malignancies for which this pathway is a known mechanism of carcinogenesis.

Researchers analyzed Streptococcus bovis, Fusobacterium nucleatum, Helicobacter pylori, Bacteroides fragilis, and Clostridium septicum. S. bovis seems to be associated with higher rates of both adenomas and carcinomas. Patients with colorectal cancer have been shown to have high concentrations of F. nucleatum and less microbial diversity than control groups. H. pylori infections appear to be associated with a 1.4-fold risk increase for colorectal cancer, although the authors mentioned that data may be controversial due to publication bias from the original research. The subtype Enterotoxigenic Bacteroides fragilis produces a toxin that has been shown to affect the development of colorectal cancer. Finally, C. septicum has not been associated with the initial appearance of colorectal cancer, but it does appear to have a mutually beneficial relationship with malignancies in progress.

“Future research may focus on whether the detection of certain bacterial concentrations within stool or biopsied polyps could serve as adjuncts to current screening modalities to help identify higher risk patients,” the authors concluded.

How to Inhale Himalayan Pink Salt to Help Remove Mucus, Bacteria and Toxins from your Lungs

How to Inhale Himalayan Pink Salt to Help Remove Mucus, Bacteria and Toxins from your Lungs


There’s a lot of information on the internet about the benefits of Himalayan salt. Many people don’t realize that unlike table salt, Himalayan salt contains the same 84 natural elements and minerals that are found in the human body, minerals which contribute to your overall health and vitality.

Its minerals are in an ionic state, which means that they are tiny enough for our cells to absorb easily.


Although it’s relatively new to the United States, salt rooms have been used for therapeutic purposes in Eastern Europe for more than 200 years. Years ago it was common practice for people with lung conditions to visit salt mines for their healing benefits. Ancient Greeks also used Halotherapy (salt therapy) for respiratory problems.

In the United States, salt therapy is becoming more widely known and appreciated with the introduction of salt rooms in spas and other wellness businesses. Salt is known for its antibacterial, anti-fungal and anti-microbial properties.

While many people visit salt mines around the world to help rid themselves of respiratory ailments of all kinds including allergies, asthma, congestion, and hay fever, others flock to salt rooms popping up in cities like New York, Orlando, and London.

But you don’t have to travel far to reap the benefits of Himalayan salt. You can enjoy the health benefits by adding Himalayan salt to your diet, routine or home. Himalayan salt is available in numerous forms such as blocks, slabs, lamps, rocks, ground salt for culinary purposes, coarse salt for baths, or you can make your own Sole.

Benefits of Salt Inhalers

Modern salt inhalers combine the best of old-world and modern technology. The small Himalayan salt rocks rest at the bottom of the inhaler. When you inhale, the natural moisture in the air absorbs the salt particles into the lungs.

This will help to reduce inflammation in the lungs and can help with other conditions such as asthma, allergies, colds, congestion, hay fever and sinus congestion. Unlike traditional inhalers, this therapeutic technique offers no negative side effects.

  • Salt is a natural expectorant and may help in reducing excess mucous.
  • Reducing mucus, may eliminate night time coughing and post nasal drip, allowing you to sleep better.
  • Himalayan salt contains 84 natural elements and minerals that are found in the human body.
  • Salt inhalation therapy can reduce redness and swelling of nasal passages.
  • Himalayan salt inhalers can reduce irritation and inflammation from pollutants and smoke.
  • Salt is known for its antibacterial, anti-fungal and anti-microbial properties. Using a salt inhaler can be used to cleanse the body of harmful organisms.

How to Use a Salt Inhaler

  1. Place Himalayan rocks inside your ceramic inhaler, (don’t use plastic inhalers) according to the package directions.
  2. Place the inhaler mouthpiece in your mouth.
  3. Breathe in normally through the mouth, and exhale through the nose.
  4. Do not add water, the inhaler is for dry therapy only.
  5. When you inhale with long slow deep breaths this will bring the salt ions to the lungs. Because the ions are so small they bypass the nasal filtering system we have and go directly into the lungs. The lungs then absorb the ions and bring them into the bloodstream. This will help to reduce inflammation and can also reduce pain in lungs from various conditions such as asthma, bronchitis or pneumonia.

NOTE: Following the cleaning directions on your inhaler package, and remember inhalers should not be shared, they are recommended for one person only. Each family member should have their own inhaler.

Although many people have seen immediate and drastic results within a few days, in general, the effects of using a Himalayan salt inhaler are more subtle than immediately dramatic and are usually noticed with regular and consistent use.

How to Refill Your Himalayan Salt Inhaler

If you need to refill the salt in the inhaler, simply open the round plastic stopper and empty out the used salt and refill with the fresh coarse Himalayan crystal salt. Plug the stopper back in.

Never refill your inhaler with anything other than Himalayan salt.

How Bacteria Help Regulate Blood Pressure

Kidneys sniff out signals from gut bacteria for cues to moderate blood pressure after meals. Our understanding of how symbiotic microbes affect health is becoming much more molecular.

In a surprising turn, researchers find that the bacteria in our guts send signals to the kidneys and blood vessels that help to balance our vital signs.

In a surprising turn, researchers find that the bacteria in our guts send signals to the kidneys and blood vessels that help to balance our vital signs.

Some years ago, when Jennifer Pluznick was nearing the end of her training in physiology and sensory systems, she was startled to discover something in the kidneys that seemed weirdly out of place. It was a smell receptor, a protein that would have looked more at home in the nose. Given that the kidneys filter waste into urine and maintain the right salt content in the blood, it was hard to see how a smell receptor could be useful there. Yet as she delved deeper into what the smell receptor was doing, Pluznick came to a surprising conclusion: The kidney receives messages from the gut microbiome, the symbiotic bacteria that live in the intestines.

In the past few years, Pluznick, who is now an associate professor of physiology at Johns Hopkins University, and a small band of like-minded researchers have put together a picture of what the denizens of the gut are telling the kidney. They have found that these communiqués affect blood pressure, such that if the microbes are destroyed, the host suffers. The researchers have uncovered a direct, molecular-level explanation of how the microbiome conspires with the kidneys and the blood vessels to manipulate the flow of blood.

The smell receptor, called Olfr78, was an orphan at first: It had previously been noticed in the sensory tissues of the nose, but no one knew what specific scent or chemical messenger it responded to. Pluznick began by testing various chemical possibilities and eventually narrowed down the candidates to acetate and propionate. These short-chain fatty acid molecules come from the fermentation breakdown of long chains of carbohydrates — what nutritionists call dietary fiber. Humans, mice, rats and other animals cannot digest fiber, but the bacteria that live in their guts can.

As a result, more than 99 percent of the acetate and propionate that floats through the bloodstream is released by bacteria as they feed. “Any host contribution is really minimal,” Pluznick said. Bacteria are therefore the only meaningful source of what activates Olfr78 — which, further experiments showed, is involved in the regulation of blood pressure.

Our bodies must maintain a delicate balance with blood pressure, as with electricity surging through a wire, where too much means an explosion and too little means a power outage. If blood pressure is too low, an organism loses consciousness; if it’s too high, the strain on the heart and blood vessels can be deadly. Because creatures are constantly flooding their blood with nutrients and chemical signals that alter the balance, the control must be dynamic. One of the ways the body exerts this control is with a hormone called renin, which makes blood vessels narrower when the pressure needs to be kept up. Olfr78, Pluznick and her colleagues discovered, helps drive the production of renin.

How did a smell receptor inherit this job? The genes for smell receptors are present in almost every cell of the body. If in the course of evolution these chemical sensors hooked up to the machinery for manufacturing a hormone rather than to a smell neuron, and if that connection proved useful, evolution would have preserved the arrangement, even in parts of the body as far from the nose as the kidneys are.

Olfr78 wasn’t the end of the story, however. While the team was performing these experiments, they realized that another receptor called Gpr41 was getting signals from the gut microbiome as well. In a paper last year, Pluznick’s first graduate student, Niranjana Natarajan, now a postdoctoral fellow at Harvard University, revealed the role of Gpr41, which she found on the inner walls of blood vessels. Like Olfr78, Gpr41 is known to respond to acetate and propionate — but it lowers blood pressure rather than raising it. Moreover, Gpr41 starts to respond at low levels of acetate and propionate, while Olfr78 kicks in only at higher levels.

Jennifer Pluznick, an associate professor of physiology at Johns Hopkins University, and her colleagues have worked out in detail how intestinal bacteria help to regulate blood pressure. In this video from the 2016 TEDMED conference, she discusses that mechanism and the physiological functions of scent detectors in other organs throughout the body.

Jennifer Pluznick, an associate professor of physiology at Johns Hopkins University, and her colleagues have worked out in detail how intestinal bacteria help to regulate blood pressure. In this video from the 2016 TEDMED conference, she discusses that mechanism and the physiological functions of scent detectors in other organs throughout the body.


Here’s how the pieces fit together: When you — or a mouse, or any other host organism whose organs and microbes talk this way — have a meal and dietary fiber hits the gut, bacteria feed and release their fatty-acid signal. This activates Gpr41, which ratchets down the blood pressure as all the consumed nutrients flood the circulation.

If you keep eating — a slice of pie at Thanksgiving dinner, another helping of mashed potatoes — Gpr41, left to itself, might bring the pressure down to dangerous levels. “We think that is where Olfr78 comes in,” Pluznick said. That receptor, triggered as the next surge of fatty acids arrives, keeps blood pressure from bottoming out by calling for renin to constrict the blood vessels.

The new understanding of how symbiotic bacteria manipulate blood pressure is emblematic of wider progress in linking the microbiome to our vital statistics and health. While vague statements about the microbiome’s effect on health have become commonplace in recent years, the field has moved beyond simply making associations, said Jack Gilbert, a microbiome researcher at the University of Chicago.

“Everybody goes on about the promise,” he said. But in fact, studies full of mechanistic details, like the ones Pluznick, her collaborators and other researchers have published, have been growing more and more numerous.

In June of last year, the National Institutes of Health convened a working group on the microbiome’s control of blood pressure. Researchers met in Maryland to thrash out what important questions still need to be answered, including what role the host’s genetic background plays — whether, for instance, the microbiome matters more for some hosts than for others.

“There’s a lot of excitement [about] getting more data,” said Bina Joe, a professor of physiological genomics and the director of the Center for Hypertension and Personalized Medicine at the University of Toledo. If you look at PubMed, she continued, there are more reviews of the microbiome literature than research papers. The review articles get new researchers interested — but there are still more details to hammer out.

Understanding those details is key to knowing whether transplanting a certain set of microbes into someone can reshape the recipient’s biology enough to cure a health problem, as some proponents of personalized medicine hope. One famous early study showed that giving lean mice the microbiome of an obese human made them obese too, while the microbiome of lean humans kept the mice lean. “There’s one paper that came out earlier this year … that showed that maybe this can happen with blood pressure as well,” Pluznick said, though she cautioned that the study was small and needed follow-up. But theoretically, even if swapping in new bacteria could only slightly lower the blood pressure of those with a genetic tendency toward hypertension, it could make a difference over the course of a lifetime.

“It might be something that’s easier to manipulate than your genes, or my genes. Those are much harder to change,” she said.

How do bacteria become resistant to lethal antibiotics? 

scanning electron micrograph showing Salmonella typhimurium (red) invading cultured human cells

scanning electron micrograph showing Salmonella typhimurium (red) invading cultured human cells   

In a new study, researchers from Indian Institute of Science (IISc), Bangalore and Indian Institute of Science Education and Research (IISER), Pune have shown how bacteria take help of Hydrogen sulphide (H2S) gas to defend themselves against the onslaught of antibiotics. The study was published in Chemical Science.

Antibiotics usually kill bacteria by inducing oxidative stress leading to accumulation of reactive oxygen species (ROS), that damage bacteria’s essential machinery –DNA and enzymes. Interestingly, when antibiotic-resistant bacteria encounter such oxygen-rich environment, they produce H2S that scavenges the excess ROS and protects the cell from damage.

To be able to study how H2S affects resistant bacterial cells, the team devised an innovative system for generating H2S inside living bacterial cells. They designed a new compound, cyclopentane-1,1-diylbis((4-nitrobenzyl) sulfane, “which is a substrate for E. coli’s  nitroreductase enzyme (NTR)  and releases H2S in presence of the enzyme inside the cell”  explains Prashant Shukla, PhD student at IISc, Bangalore, and one of the authors of this study.

The NTR enzyme is expressed exclusively in bacteria and not in mammalian cells. “We wanted to exclude possibilities of host-derived  H2S  playing a role in our experiments with intracellular pathogens such as Salmonella and Mycobacterium.” says Harinath Chakrapani, Associate Professor, at IISER, Pune and an author on the paper.

The designed donor was able to permeate inside healthy bacterial cells while retaining their functionality. When donor loaded bacterial cells were exposed to hydrogen peroxide (H2O2), which is a good source of ROS, the H2S released by donor present inside the bacterial cells was able to reduce it and protect the cell from damage.

The authors also examined if elevated endogenous  H2S  levels showed a positive correlation with drug resistance in human infections. “We measured the intracellular H2S levels of several multidrug-resistant (MDRE. coli strains isolated from patients suffering from urinary tract infections (UTI). The endogenous H2S levels were considerably higher than non-pathogenic strains (of bacteria) indicating a possible functional role for H2S in antibiotic resistance”, says Shukla. The authors were also able to show that inhibition of H2Sbiosynthesis reversed antibiotic resistance in MDR varieties of UTI-causing bacteria. UTI affects millions in India and indiscriminate use of antibiotics has made UTI pathogens resistant to most antibiotics.

Amit Singh, Assistant Professor at IISc and one of the authors of the study says “A combination of molecules/drugs targeting H2S biosynthesis, antioxidants, and an alternate route of respiration could have a remarkable impact on reversing drug resistance and clinical outcomes”.

Vasanthi Ramachandran, Director of Microbiology Division, Bug Works, who is unrelated to the study, says, “the authors have used a novel approach to substantiate the role of H2S towards antibiotic resistance. Adding that, “the study has definitely shown and opened up newer avenues including novel targets that can be exploited to understand and overcome resistance.”

Mad Scientist Injects Himself A 3.5 Million-Year-Old Permafrost Bacteria. The Results Are Shocking!

In what sounds like a story fit for a Marvel comic, Anatoli Brouchkov, a controversial Russian Scientist has injected himself with bacteria that is 3.5 million years old, and, more astounding, has stated that this is the elusive key to “eternal life”.

Found in the Siberian permafrost, these cells have made him feel stronger and healthier than he ever has before and, he claims, have a high resistance to environmental factors and astonishing levels of vitality. It is also claimed that tests undertaken on animals have resulted in the cells showing a marked increase in physical activity and a fortified immune system.


Head of the Geocryology Department at Moscow State University, Professor Anatoli Broushkov has not succumbed to illness in two years, since he first started the experiments on himself, according to the Russian Media.

Labelled “Bacillus F”, the 3.5 million-year-old bacteria is believed to one of the key components in improving longevity in humans. Once the DNA was unlocked by Researchers from Russia, it was tested on both mice and human cells. However, Broushkov decided to become a human guinea pig and tested it out on himself. The results of this, he claims: A strong and healthy body that is resisting time better than it did before.

So what is the secret of this bacteria? Well, Bacillus F has managed to survive for millions of years in the arctic tundra of Siberia, a place known to be one of the most extreme places on Earth.

As global warming spreads across Siberia, the permafrost has started melting, and this, Broushjov believes, has caused the bacteria to infiltrate into the natural environment, getting into the water supply of local populations. He believed that there would be no danger in experimenting on himself as he claims the Yakut people have been imbibing the bacteria naturally for some time, and this race seems to have greater longevity, despite their hard living conditions. ‘I started to work longer, I’ve never had the flu for the last two years, ’ he told The Siberian Times.

As with many scientific discoveries, it is not always easy to determine how something works, and in the case of Bacillus F, Broushkov claims it is the same. However, he will continue to conduct the experiments under scientific conditions to discover the impact and of course, to identify potential side-effects.

‘If we can find how the bacteria stays alive we probably would be able to find a tool to extend our lives, ’ he explained in an interview.

This Jurassic bacterium could also be an integral factor in fertility as well as longevity in humans, say the scientists. Older female mice that were injected with Bacillus F were able to reproduce after they had ceased being able to. Also, Bacillus F also can heal plants.

Claimed to be akin to discovering the Holy Grail, Dr. Viktor Chernyavsky, an epidemiologist from Yakutsk said ‘The bacteria gives out biologically active substances throughout its life, which activates the immune status of experimental animals.’

Watch the video. URL:


Not Even Bacteria Are Safe from Climate Change

Climate change has started to touch every living thing, and not even bacteria are immune from its effects.

The Earth’s warmer environment is killing off some of the world’s microbiological diversity, some of which acts as warning signals for greater environmental impacts in their ecosystems, according to a study published this week in Nature Communications. Since microbes make up the foundation of any food chain, any major impact to them might trickle down through the food chain and could impact entire ecosystems.

The study looked at bacteria and other microbes in various ecosystems, including harsh ones like high-elevation areas or frozen tundras. It found that microbes in icy environments were similar to ones in mountainous tropical regions. This suggests changes in temperature and other impacts are causing some types of microbes to die off, reducing the Earth’s microbial diversity.

“We’ve historically studied birds, mammals and plants, but we know very little about biotechnology of microbes,” said Janne Soininen, a study author from the University of Helsinki in a statement.

Figuring out how temperature changes and the increase in nutrients in water from climate change can help scientists understand how climate change will affect the very building blocks of certain ecosystems, a release announcing the study stated.

“The typically austere, i.e. nutrient-poor, waters in the north, for example, are extremely susceptible to temperature variations, and as the climate warms up, species that have adapted to the cold will decline.”

Scientists Discover That Bacteria Have a Collective Memory

Collective motion can be observed in biological systems over a wide range of length scales, from large animals to fish to bacteria, because collective systems always work better for adaptation than those which are singular.

Scientists Discover That Bacteria Have a Collective Memory

Individual bacterial cells have short memories. But groups of bacteria can develop a collective memory that can increase their tolerance to stress. This has been demonstrated experimentally for the first time in a study by Eawag and ETH Zurich scientists published in PNAS.

A central question in the study of biological collective motion is how the traits of individuals give rise to the emergent behavior at population level. This question is relevant to the dynamics of general self-propelled particle systems, biological self-organization, and active fluids. Bacteria provide a tractable system to address this question, because bacteria are simple and their behavior is relatively easy to control.

Bacteria exposed to a moderate concentration of salt survive subsequent exposure to a higher concentration better than if there is no warning event. But in individual cells this effect is short-lived: after just 30 minutes, the survival rate no longer depends on the exposure history. Now two Eawag/ETH Zurich microbiologists, Roland Mathis and Martin Ackermann, have reported a new discovery made under the microscope with Caulobacter crescentus, a bacterium ubiquitous in freshwater and seawater.

When an entire population is observed, rather than individual cells, the bacteria appear to develop a kind of collective memory. In populations exposed to a warning event, survival rates upon a second exposure two hours after the warning are higher than in populations not previously exposed. Using computational modelling, the scientists explained this phenomenon in terms of a combination of two factors.

Firstly, salt stress causes a delay in cell division, leading to synchronization of cell cycles; secondly, survival probability depends on the individual bacterial cell’s position in the cell cycle at the time of the second exposure. As a result of the cell cycle synchronization, the sensitivity of the population changes over time. Previously exposed populations may be more tolerant to future stress events, but they may sometimes even be more sensitive than populations with no previous exposure.

Scientists Discover That Bacteria Have a Collective Memory - Collective Motion Visible in Fish Populations
Collective motion is commonly observed in fish populations.

Martin Ackermann comments: “If we understand this collective effect, it may improve our ability to control bacterial populations.” The findings are relevant, for example, to our understanding of how pathogens can resist antibiotics, or how the performance of bacterial cultures in industrial processes or wastewater treatment plants can be maintained under dynamic conditions. After all, bacteria play a crucial role in almost all bio- and geochemical processes. From a human perspective, depending on the particular process, they are either beneficial — e.g. if they break down pollutants or convert nutrients into energy — or harmful, especially if they cause diseases. For the researchers, says Mathis, another important conclusion can be drawn: “If you want to understand the behaviour and fate of microbial populations, it’s sometimes necessary to analyse every single cell.”

Bacteria also have the collective capacity to generate many neurotransmitters and neuromodulators. For example, certainLactobacillus and Bifidobacterium species produce gamma-aminobutyric acid (GABA);Escherichia, Bacillus andSaccharomyces produce norepinephrine (NE).

Future studies of how microbes contribute to the function of their host on all levels will play an important role in advancing understanding of health disorders as well as disorders of social interaction.

Whiten Your Teeth With This Fermentation Which Kills Bacteria, Removes Stains, and Tartar

This vinegar is made by fermenting apples. It is rich in pectin and is excellent for the treatment of mouth and throat. It kills bacteria, removes stains from teeth, and removes tartar.

How to use vinegar to whiten teeth?

  • Pour a teaspoon of vinegar in a large glass of water (2.5 dl) and stir.
  • Every morning, before brushing teeth, clean your mouth with solution of vinegar, then brush with a toothbrush.
  • Then brush your teeth toothpaste, as usual.
Whiten Your Teeth With This Fermentation
Whiten Your Teeth With This Fermentation

Important notes:

  • Be careful not to make a stronger solution than prescribed because this may damage your teeth.
  • Every time before application, stir the remaining liquid in the glass.

The Bacteria In Some Women’s Reproductive Systems Have A Natural Defense Against HIV

The female reproductive system may have a natural defense against HIV, which could protect women from developing the virus, as well as other sexually transmitted diseases (STDs). In their new study published in mBio, researchers from the University of North Carolina at Chapel Hill have found that a specific type of vaginal bacteria may trap the infection before it has a chance to spread.


According to Sam Lai, senior author of the study and assistant professor at the UNC Eshelman School of Pharmacy, vaginal microbiota that mainly contain any bacterial species of Lactobacillus are considered healthy. But a specific strain of lactobacillus, known asLactobacillus crispatus, may be the key to stopping HIV in its tracks. If this is the case, the researchers believe that their study will eventually help protect women from this devastating infection.

“What we discovered is that a woman’s risk of being infected by HIV can be affected by the type of helpful bacteria present in vaginal mucus,” Lai said in a recent press release. “We found that vaginal microorganisms, including specific species of Lactobacillus bacteria, can directly alter the protective properties of cervicovaginal mucus.”

For the study, the researchers looked at the bacterial composition of 31 women’s reproductive system. Under a high-resolution, time-lapse microscope, the researchers observed how an HIV pseudovirus reacted when presented to mucus containing lactobacillus crispatus, and mucus containing other strains of bacteria.

Overall, the researchers observed that the mucus containing lactobacillus crispatus was very good at trapping HIV and stopping it from spreading. They found, though, that this ability was not related to the mucus’ pH, total lactic acid, or Nugent score, which are all indicators of vaginal health and how much Lactobacillus bacteria is present when compared with other forms of microbes.

But, the researchers did observe higher levels of D-lactic acid in the mucus that effectively trapped HIV. Because humans do not naturally make D-lactic acid, the researchers attributed its presence to the bacteria within the mucus.

While Lactobacillus crispatus was a good match for fighting HIV, mucus either dominated byLactobacillus iners or a variety of other bacterial species like gardnerella vaginalis, both associated with bacterial vaginosis, did not stop HIV from spreading. Interestingly enough, the researchers observed that women in developing countries, including countries in Africa, mainly have these types of vaginal microbiota, which are ineffective at blocking HIV.

Lai said this research builds on findings from 2014, where the team discovered that IgG antibodies in mucus have the potential to trap pathogens like the herpes virus. With the help of the antibodies, the researchers hope to develop a formula that can immobilize pathogens by using mucus as their vehicle.

Signature dishes

As people pass through life they leave a trail of bacteria in their wake

THERE is indeed a cloud hanging over you: your own personal cloud of microbes. People constantly generate puffs of bacteria, even when they are sitting perfectly still. And researchpublished in PeerJ, by James Meadow, then at the University of Oregon, and his colleagues, suggests that, like a fingerprint or a sample of DNA, these bacteria may be able to identify who someone is.

People shed bacteria—from their skin, mouths, noses and other orifices—at a rate of about 1m an hour. But until Dr Meadow’s study, no one had looked at the details. Dr Meadow therefore decided to sit volunteers down, alone, in a sterile chamber for up to four hours at a time and collect what floated off them.

The chamber in question, a white-panelled room, with a wall-high window at the front, was ventilated with filtered air that came in through a hole in its ceiling. It was scrubbed clean with disinfectant before every use. The team’s volunteers (six men and five women) dressed in new, clean, identical tank-tops and shorts, and sat for the requisite time in a disinfected plastic swivel chair at the chamber’s centre. Each was allowed a sterile laptop, to communicate with the researchers and to alleviate boredom.

Dr Meadow collected bacteria both from air leaving the chamber (which it did via a hole in the floor), and from a ring of Petri dishes that surrounded the seated volunteer. These dishes caught debris heavy enough to settle. Both types of sample then had their DNA content analysed. That revealed which bacteria they contained—which turned out to be similar, regardless of sample type, for a given individual.

Samples did, though, vary from one person to another—both by sheer amount given off and by the relative proportions of what each cloud contained. Some people had moreStaphylococcus epidermidis, a bacterium found on human skin, for instance, while others had more Streptococcus oralis, one that frequents the mouth. Women were easily distinguished from men, because they shed bacteria typically found in the female reproductive tract. Each person’s bacterial cloud, Dr Meadow says, was statistically distinct.

This finding raises the possibility that microbial “footprints” left at the scenes of crimes might one day be useful to forensic scientists. A criminal who took care to leave none of his own DNA behind would find it hard to avoid leaving bacteria. (He would, after all, have to breathe.) For this to work, someone’s bacterial profile would have not only to be unique, but also stable—which has yet to be established. If it is, though, scientific sleuthing will have acquired yet another tool, and false alibis will have become yet harder to establish.

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