80 MILLION BACTERIA SEALED WITH A KISS

As  many as 80 million bacteria are transferred during a 10 second kiss, according to research published in the open access journalMicrobiome. The study also found that partners who kiss each other at least nine times a day share similar communities of oral bacteria

The ecosystem of more than 100 trillion microorganisms that live in our bodies -- the microbiome -- is essential for the digestion of food, synthesizing nutrients, and preventing disease. It is shaped by genetics, diet, and age, but also the individuals with whom we interact. With the mouth playing host to more than 700 varieties of bacteria, the oral microbiota also appear to be influenced by those closest to us.

Researchers from Micropia and TNO in the Netherlands studied 21 couples, asking them to fill out questionnaires on their kissing behaviour including their average intimate kiss frequency. They then took swab samples to investigate the composition of their oral microbiota on the tongue and in their saliva.

The results showed that when couples intimately kiss at relatively high frequencies their salivary microbiota become similar. On average it was found that at least nine intimate kisses per day led to couples having significantly shared salivary microbiota.

Lead author Remco Kort, from TNO's Microbiology and Systems Biology department and adviser to the Micropia museum of microbes, said: "Intimate kissing involving full tongue contact and saliva exchange appears to be a courtship behavior unique to humans and is common in over 90% of known cultures. Interestingly, the current explanations for the function of intimate kissing in humans include an important role for the microbiota present in the oral cavity, although to our knowledge, the exact effects of intimate kissing on the oral microbiota have never been studied. We wanted to find out the extent to which partners share their oral microbiota, and it turns out, the more a couple kiss, the more similar they are."

In a controlled kissing experiment to quantify the transfer of bacteria, a member of each of the couples had a probiotic drink containing specific varieties of bacteria including Lactobacillus and Bifidobacteria. After an intimate kiss, the researchers found that the quantity of probiotic bacteria in the receiver's saliva rose threefold, and calculated that in total 80 million bacteria would have been transferred during a 10 second kiss.

The study also suggests an important role for other mechanisms that select oral microbiota, resulting from a shared lifestyle, dietary and personal care habits, and this is especially the case for microbiota on the tongue. The researchers found that while tongue microbiota were more similar among partners than unrelated individuals, their similarity did not change with more frequent kissing, in contrast to the findings on the saliva microbiota.

Commenting on the kissing questionnaire results, the researchers say that an interesting but separate finding was that 74% of the men reported higher intimate kiss frequencies than the women of the same couple. This resulted in a reported average of ten kisses per day from the males, twice that of the female reported average of five per day.

To calculate the number of bacteria transferred in a kiss, the authors relied on average transfer values and a number of assumptions related to bacterial transfer, the kiss contact surface, and the value for average saliva volume.

CERTAIN GUT BACTERIA MAY INDUCE METABOLIC CHANGES FOLLOWING EXPOSURE TO ARTIFICIAL SWEETENERS TNERESW

Artificial sweeteners -- promoted as aids to weight loss and diabetes prevention -- could actually hasten the development of glucose intolerance and metabolic disease, and they do so in a surprising way: by changing the composition and function of the gut microbiota -- the substantial population of bacteria residing in our intestines. These findings, the results of experiments in mice and humans, were published September 17 in Nature. Dr. Eran Elinav of the Weizmann Institute of Science's Department of Immunology, who led this research together with Prof. Eran Segal of the Department of Computer Science and Applied Mathematics, says that the widespread use of artificial sweeteners in drinks and food, among other things, may be contributing to the obesity and diabetes epidemic that is sweeping much of the world

For years, researchers have been puzzling over the fact that non-caloric artificial sweeteners do not seem to assist in weight loss, with some studies suggesting that they may even have an opposite effect. Graduate student Jotham Suez in Dr. Elinav's lab, who led the study, collaborated with lab member Gili Zilberman-Shapira and graduate students Tal Korem and David Zeevi in Prof. Segal's lab to discover that artificial sweeteners, even though they do not contain sugar, nonetheless have a direct effect on the body's ability to utilize glucose. Glucose intolerance -- generally thought to occur when the body cannot cope with large amounts of sugar in the diet -- is the first step on the path to metabolic syndrome and adult-onset diabetes.

The scientists gave mice water laced with the three most commonly used artificial sweeteners, in amounts equivalent to those permitted by the U.S. Food and Drug Administration (FDA). These mice developed glucose intolerance, as compared to mice that drank water, or even sugar water. Repeating the experiment with different types of mice and different doses of the artificial sweeteners produced the same results -- these substances were somehow inducing glucose intolerance.

Next, the researchers investigated a hypothesis that the gut microbiota are involved in this phenomenon. They thought the bacteria might do this by reacting to new substances like artificial sweeteners, which the body itself may not recognize as "food." Indeed, artificial sweeteners are not absorbed in the gastrointestinal tract, but in passing through they encounter trillions of the bacteria in the gut microbiota.

The researchers treated mice with antibiotics to eradicate many of their gut bacteria; this resulted in a full reversal of the artificial sweeteners' effects on glucose metabolism. Next, they transferred the microbiota from mice that consumed artificial sweeteners to "germ-free," or sterile, mice -- resulting in a complete transmission of the glucose intolerance into the recipient mice. This, in itself, was conclusive proof that changes to the gut bacteria are directly responsible for the harmful effects to their host's metabolism. The group even found that incubating the microbiota outside the body, together with artificial sweeteners, was sufficient to induce glucose intolerance in the sterile mice. A detailed characterization of the microbiota in these mice revealed profound changes to their bacterial populations, including new microbial functions that are known to infer a propensity to obesity, diabetes, and complications of these problems in both mice and humans.

Does the human microbiome function in the same way? Dr. Elinav and Prof. Segal had a means to test this as well. As a first step, they looked at data collected from their Personalized Nutrition Project ,the largest human trial to date to look at the connection between nutrition and microbiota. Here, they uncovered a significant association between self-reported consumption of artificial sweeteners, personal configurations of gut bacteria, and the propensity for glucose intolerance. They next conducted a controlled experiment, asking a group of volunteers who did not generally eat or drink artificially sweetened foods to consume them for a week, and then undergo tests of their glucose levels and gut microbiota compositions.

The findings showed that many -- but not all -- of the volunteers had begun to develop glucose intolerance after just one week of artificial sweetener consumption. The composition of their gut microbiota explained the difference: the researchers discovered two different populations of human gut bacteria -- one that induced glucose intolerance when exposed to the sweeteners, and one that had no effect either way. Dr. Elinav believes that certain bacteria in the guts of those who developed glucose intolerance reacted to the chemical sweeteners by secreting substances that then provoked an inflammatory response similar to sugar overdose, promoting changes in the body's ability to utilize sugar.

Prof. Segal states, "The results of our experiments highlight the importance of personalized medicine and nutrition to our overall health. We believe that an integrated analysis of individualized 'big data' from our genome, microbiome, and dietary habits could transform our ability to understand how foods and nutritional supplements affect a person's health and risk of disease."

According to Dr. Elinav, "Our relationship with our own individual mix of gut bacteria is a huge factor in determining how the food we eat affects us. Especially intriguing is the link between use of artificial sweeteners -- through the bacteria in our guts -- to a tendency to develop the very disorders they were designed to prevent; this calls for reassessment of today's massive, unsupervised consumption of these substances."

BACTERIA FROM BEES POSSIBLE ALTERNATIVE TO ANTIBIOTICS

Raw honey has been used against infections for millennia, before honey -- as we now know it -- was manufactured and sold in stores. So what is the key to its' antimicrobial properties? Researchers at Lund University in Sweden have identified a unique group of 13 lactic acid bacteria found in fresh honey, from the honey stomach of bees. The bacteria produce a myriad of active antimicrobial compounds.

These lactic acid bacteria have now been tested on severe human wound pathogens such as methicillin-resistant Staphylococcus aureus (MRSA),Pseudomonas aeruginosa and vancomycin-resistantEnterococcus (VRE), among others. When the lactic acid bacteria were applied to the pathogens in the laboratory, it counteracted all of them.

While the effect on human bacteria has only been tested in a lab environment thus far, the lactic acid bacteria has been applied directly to horses with persistent wounds. The LAB was mixed with honey and applied to ten horses; where the owners had tried several other methods to no avail. All of the horses' wounds were healed by the mixture.

The researchers believe the secret to the strong results lie in the broad spectrum of active substances involved.

"Antibiotics are mostly one active substance, effective against only a narrow spectrum of bacteria. When used alive, these 13 lactic acid bacteria produce the right kind of antimicrobial compounds as needed, depending on the threat. It seems to have worked well for millions of years of protecting bees' health and honey against other harmful microorganisms. However, since store-bought honey doesn't contain the living lactic acid bacteria, many of its unique properties have been lost in recent times," explains Tobias Olofsson.

The next step is further studies to investigate wider clinical use against topical human infections as well as on animals.

The findings have implications for developing countries, where fresh honey is easily available, but also for Western countries where antibiotic resistance is seriously increasing.

RECRUITING BACTERIA SELF HEALING MATERIALS

For most people biofilms conjure up images of slippery stones in a streambed and dirty drains. While there are plenty of "bad" biofilms around -- they even cause pesky dental plaque and a host of other more serious medical problems -- a team at the Wyss Institute for Biologically Inspired Engineering at Harvard University sees biofilms as a robust new platform for designer nanomaterials that could clean up polluted rivers, manufacture pharmaceutical products, fabricate new textiles, and more.

In short, they want to give biofilms a facelift, and have developed a novel protein engineering system called BIND to do so. Using BIND, which stands for Biofilm-Integrated Nanofiber Display, the team said biofilms could be tomorrow's living foundries for the large-scale production of biomaterials that can be programmed to provide functions not possible with existing materials. They have reported the proof-of-concept in Nature Communications .

"Most biofilm-related research today focuses on how to get rid of biofilms, but we demonstrate here that we can engineer these super tough natural materials to perform specific functions -- so we may want them around in specific quantities and for specific applications," said Wyss Institute Core Faculty member Neel Joshi, Ph.D., the study's senior author. Joshi is also an Associate Professor of Chemical and Biological Engineering at the Harvard School of Engineering and Applied Sciences (SEAS).

Biofilms also self-assemble and self-heal. "If they get damaged, they grow right back because they are living tissues," said lead author Peter Nguyen, Ph.D., a Postdoctoral Fellow at the Wyss Institute and Harvard SEAS.

Biofilms are communities of bacteria ensconced in a slimy, but extremely tough, matrix of extracellular material composed of sugars, proteins, genetic material and more. During biofilm formation individual bacteria pump out proteins that self-assemble outside the cell -- creating tangled networks of fibers that essentially glue the cells together into communities that keep the bacteria safer than they would be on their own.

Interest in biofilm engineering is skyrocketing, and while several other teams have recently developed genetic tools to control biofilm formation, Joshi's team altered the composition of the extracellular material itself -- essentially turning it into a self-replicating production platform to churn out whatever material they wish to produce.

"Until recently there was not enough cooperation between synthetic biologists and biomaterials researchers to exploit the synthetic potential of biofilms this way. We are trying to bridge that gap," Joshi said.

The team genetically fused a protein with a particular desired function -- for example, one known to adhere to steel -- onto a small protein called CsgA that is already produced by E. coli bacteria. The appended domain then went along for the ride through the natural process by which CsgA gets secreted outside the cell, where it self-assembled into supertough proteins called amyloid nanofibers. These amyloid proteins retained the functionality of the added protein -- ensuring in this case that the biofilm adhered to steel.

Amyloid proteins traditionally get a bad rap for their role in causing tremendous health challenges such as Alzheimer's disease, but in this case their role is fundamental to making BIND so robust. These amyloids can spontaneously assemble into fibers that, by weight, are stronger than steel and stiffer than silk.

"We are excited about the versatility of the method, too," Joshi said. The team demonstrated an ability to fuse 12 different proteins to the CsgA protein, with widely varying sequences and lengths. This means in principle that they can use this technology to display virtually any protein sequence -- a significant feature because proteins perform an array of impressive functions from binding to foreign particles to carrying out chemical reactions, transmitting signals, providing structural support, and transporting or storing certain molecules.

Not only can these functions be programmed into the biofilm one at a time, but they can be combined to create multifunctional biofilms as well.

The concept of the microbial factory is not a new one, but for the first time it is being applied to materials, as opposed to soluble molecules like drugs or fuels. "We are essentially programming the cells to be fabrication plants," Joshi said. "They don't just produce a raw material as a building block, they orchestrate the assembly of those blocks into higher order structures and maintain that structure over time."

"The foundational work Neel and his team are doing with biofilms offers a glimpse into a much more environmentally sustainable future where gargantuan factories are reduced to the size of a cell that we can program to manufacture new materials that meet our everyday needs -- from textiles to energy and environmental clean-up," said Wyss Institute Founding Director Don Ingber, M.D., Ph.D.

For now the team has demonstrated the ability to program E. coli biofilms that stick to certain substrates, such as steel, others that can immobilize an array of proteins or promote the templating of silver for construction of nanowires.