PROBIOTIC ORGANISMS IN FOOD DETECTABLE WITH NEW TECHNOLOGY
Five things to know about probiotics
From the News Desk of Jeanne Hambleton
Posted July 27, 2014 – Stone Hearth News
Citation – Investigación y Desarrollo
In the food industry is very important to ensure the quality and safety of products consumed by the population to improve their properties and reduce foodborne illness. Therefore, a team of Mexican researchers developed a sensing microbiosensor that detects beneficial bacteria.
This micromechanical device, which is known for being inexpensive, fast, selective and reliable, is the first of its kind manufactured in the country, and has been used to evaluate the growth of L. plantarum 299vm, a probiotic microorganism useful in the development of fermented dairy products.
The biosensor is able to monitor the growth of about 400 cells in just 30 minutes, compared with the traditional method that requires at least 24 hours of incubation.
This technology, which has potential application in the food industry and the health sector, was developed by specialists of the National Polytechnic Institute (IPN) in collaboration with the Mexican Oil Institute (IMP) and the development of the research project obtained the National Award for Food Science and Technology 2013 (PNCTA) in the Professional Category of Food Technology, which has been organized for the last 38 years by the National Council for Science and Technology (CONACYT) and the Mexican Industry Coca-Cola.
Jorge Perez Chanona, researcher at the National School of Biological Sciences (ENCB) at IPN, indicates that these devices have high sensitivity and will soon be portable and inexpensive.
“We have built the microbiosensor as a pilot to evaluate its potential in biosensing bacteria; the device is based on the resonance advantage of a lever or beam (holder chip) of micron size, to evaluate small changes in mass of the order of nanograms (which is the approximate weight of a bacterium).”
Chanona Pérez explains that the microbiosensor was built with a holder chip supporting a fabricated silicon beam of 125 microns long by 50 wide and 4 of thickness.
The holder chip is chemically and biologically modified and microcapillaries were used to coat the substrate with a specific growth of lactic acid bacteria, then inoculated with the “problem” sample, and the beam was vibrated at a specific resonance frequency matching the atomic scanner microscope, which allows monitoring the damping experienced by the holder chip due to small mass changes that occur when microorganisms grow on its surface, similar to the behavior of a trampoline when you add more weight, thus detecting possible bacterial growth dynamics within minutes of inoculation.
The IPN specialist details that besides these beneficial bacteria, micro and nano-biosensors can detect other microorganisms as pathogens; fungi; yeast; infectious agents (viruses); toxins; pollution particles and biomolecules, from different sources, such as water, air, soil or food.
The percentage of biosensors based on micro and nanotechnology for marketed food is still minimal, the country is just beginning to work in biological or medical applications, making it a field of opportunities for the development of basic science and technological innovation.
The construction of the microbiosensor was conceived four years ago and was the result of the thesis work of Angelica Gabriela Mendoza Madrigal. It required a multidisciplinary team of specialists, in which researchers Juan Vicente Mendez, Georgina Calderon Dominguez, Eduardo Palacios Gonzalez and Humberto Hernandez Sanchez, studying the doctorate in food, at the National School of Biological Sciences, from the Center for Nanoscience and Micro and Nanotechnologies participated, and the Mexican Oil Institute.
This was the first award handed by the PNCTA related to the area of micro and nanotechnology, in order to motivate and stimulate the generation of expertise and human resources in these disciplines and foster technological contributions in the areas of knowledge of the food and beverages industry.
PROBIOTICS AND PREBIOTICS: TAKING CARE OF THE BACTERIA THAT LIVE IN YOUR GUT
From the News Desk of Jeanne Hambleton Updated May 2014
By Giana Angelo, Ph.D. Linus Pauling Institute Research Associate ç Micronutrient Information Center.
Over the past 30 years, evidence has accumulated that the microscopic organisms that live in our digestive tract play a prominent role in health and well-being. Although it is a complex relationship with much still to be learned, we know that it is a two-way street: what we eat influences the composition and activity of our gut microbiota, and conversely, the nutritional value of food can be influenced by the microbes that inhabit our gut.
The Gut Microbiota
The gut microbiota refers to the collection of microbial species that live in the lower gastrointestinal tract (see Terminology box). We are born germ free but quickly colonized by bacteria from our mothers and the environment. Mode of delivery, early microbial exposure, diet, and host genetics have all been implicated in shaping one’s microbiota. Our gut microbiota stabilizes by about age three, with trillions of different bacteria inhabiting our gut.
The composition of the gut microbiota changes rapidly in response to diet. For example, one experiment showed that within two days of eating an animal-based versus a plant-based experimental diet, microbial composition was altered such that certain clusters of bacteria characterized each dietary pattern. Upon withdrawal of the experimental diet, the microbial composition reverted back to its baseline state just as quickly. In addition to diet, incorporating probiotics and prebiotics (see below) are other strategies to modify the composition of the gut microbiota.
The bacteria in our gut provide many important functions for the host. They protect against pathogens, extract nutrients and energy from food, contribute to normal immune function, and synthesize some vitamins, including vitamin K, which is bioavailable to the host. A growing body of evidence indicates that the functional potential of the microbiota may go even farther than these established roles.
Energy balance/obesity. Although we each have a unique bacterial “fingerprint,” these many different bacterial species fall into two major groups: Bacteroidetes and Firmicutes. The ratio of Bacteroidetes to Firmicutes inhabiting our colon has been linked to obesity—obese individuals have fewer Bacteroidetes and more Firmicutes compared to lean individuals. But this ratio can be modulated: after one year on a calorie-restricted diet (either fat- or carbohydrate-restricted), progressive weight loss in obese subjects was accompanied by a shift in the skewed proportions of Bacteroidetes to Firmicutes to more closely resemble that of lean individuals.
So how might the proportions of Bacteroidetes to Firmicutes affect energy balance? By isolating and transplanting the fecal microbiota (which accurately recapitulates the gut microbiota) from obese and lean individuals into germ-free mice, scientists can now study how these microbial signatures influence various aspects of physiology. Recipient mice acquire the body composition of the human donor (i.e., increased body mass and adiposity when transplanted with the obese microbiota). Although the gut microbiota from obese and lean donors differ metabolically, we do not yet know how these differences may influence energy balance. Certain types of bacteria may be more efficient at generating energy from food or may produce signals that influence satiety and hunger.
- Atherosclerosis. Inside the dark, anaerobic environment of the large intestine, bacterial fermentation of undigested foodstuff yields short-chain fatty acids, alcohol, gases, and other small molecules. These metabolic products represent one mechanism by which gut microbes can influence host health.
Bacterial fermentation of dietary choline (found in eggs, turkey, and beef) produces a compound known as trimethylamine (TMA). In the liver, TMA is enzymatically converted to trimethylamine-N-oxide (TMAO). TMAO has been implicated as a potential causative factor in the development of atherosclerosis because it increases macrophage cholesterol accumulation and foam cell formation, early events in the development of atherosclerotic plaque. New research suggests that one’s bacterial community could affect the amount of TMAO that is produced upon exposure to dietary choline, thereby influencing the impact of diet on cardiovascular disease (CVD) risk. It’s too soon to tell, but this “diet-microbiota interaction” could represent a new risk factor for CVD.
Probiotics are live, beneficial microorganisms that can be ingested as a dietary supplement or in food. Yogurt products that state “live and active cultures” on the label contain probiotics. Other sources include naturally fermented foods like unpasteurized sauerkraut and kimchi, and traditionally cultured dairy products like kefir and acidophilus milk. Commercial probiotics typically provide Lactobacilli or Bifidobacteria. Keep in mind that these bacteria colonize the gut only temporarily, making regular consumption necessary to sustain their population in the gut.
While many health benefits are touted (see box), strong scientific evidence currently exists for the use of probiotics for only two indications: as a supplement to antibiotic therapy to prevent acute diarrhea and adverse effects in the intestinal environment and to prevent atopic dermatitis (eczema) in infants.
Prebiotics are food for gut microbes. A prebiotic cannot be broken down by human digestive enzymes but can be fermented by gut bacteria. These non-digestible substrates are thought to selectively stimulate the growth of beneficial bacteria in the colon.
Food products with prebiotic effects are typically non-digestible carbohydrates. The two compounds most extensively tested and with confirmed prebiotic effects are inulin-type fructans (ITFs) and galacto-oligosaccharides (GOS). Both ITF and GOS selectively increase Bifidobacteria and Lactobacilli, bacterial strains that are also available as probiotics. ITFs occur naturally in several foods, such as leeks, asparagus, artichokes, garlic, onions, chicory, wheat, bananas, and soybeans. Other sources of prebiotics include honey, oatmeal, red wine, and legumes.
As with probiotics, the influence of a prebiotic ingredient on the gut microbiota is transient. Changes in microbial composition respond rapidly—within 24 hours of exposure—and disappear equally fast upon withdrawal of the prebiotic compound.
We are at any early stage in the discovery process of the effects of probiotics and prebiotics. It is difficult to identify the explicit effects of your microbiota on your health, and no specific recommendations can yet be made. We do know, however, that there is an interaction—we coexist with these microscopic organisms, and they can help us or harm us depending on how they are treated.
As we await more scientific information, the good news is that following the existing dietary guidelines will provide prebiotic and probiotic compounds, for example, from fruit, vegetables, and yogurt. These recommendations establish a framework that is good for both your body and the little microscopic organisms with which it coexists.
Do Probiotics Affect Bowel Regularity?
According to the Activia® website (Activia.us.com), the product makers state: “Clinical studies show that Activia® with B. Lactis DN 173-010 helps with slow intestinal transit or occasional irregularity when consumed 3 times per day for 2 weeks as part of a balanced diet and healthy lifestyle.”
A 2011 systematic review and meta-analysis of 11 clinical trials with 464 participants reported that probiotic supplementation has a modest effect on reducing bowel transit time, mainly in the elderly and those with initial slow transit time. B. Lactis DN 173-010 (three trials, 139 participants) and B. Lactis HN019 (two trials) were deemed to have the most significant treatment effects.
Yogurt is an excellent package of nutrients, and the regular consumption of yogurt has been associated with many positive health effects, such as improved cardiovascular health and successful weight management. The presence of pro- and prebiotics in yogurt may even mediate these and other health effects; scientists are still gathering information. The possibility of reduced transit time may be yet another reason to consume yogurt, but the benefit depends on the frequency of consumption and type of probiotics.
|TERMINOLOGYMicrobe — a microscopic organism, such as a bacterium, virus, or fungusBiota – from Greek, meaning “all life”Microbiota — the collection of microbial species that live on and within an individual
Gut microbiota — the collection of microbial species that live specifically in the lower gastrointestinal tract (colon)
Microflora, gut flora — often used interchangeably with gut microbiota
Microbiome — all of the genes that comprise one’s microbiota
Probiotic — live cultures of beneficial microbes that can be ingested as a dietary supplement or food additive
Prebiotic — non-digestible food ingredients that promote the growth of beneficial gut microbes
Antibiotic — a medication that kills microbes
STUDY POINTS TO POTENTIAL NEW TARGET FOR ANTIBIOTICS AGAINST E. COLI, OTHER BUGS
Scientists identify protein in bacteria with essential role in survival
From the FMS Global News Desk of Jeanne Hambleton
Embargo expired: 10-Jul-2014 2:00 PM EDT
Source Newsroom: Ohio State University
Newswise — COLUMBUS, Ohio – Scientists have identified a protein that is essential to the survival of E. coli bacteria, and consider the protein a potential new target for antibiotics.
In the study, the researchers confirmed that this protein, called MurJ, flips a fatty molecule from one side of a bacterial cell membrane to the other. If that molecule is not flipped, the cell cannot construct a critical layer that keeps pressurized contents of the cell contained. If those contents aren’t contained, the cell bursts.
- coli is part of the gram-negative family of bacteria, characterized by having an extra membrane, called the outer membrane, that reduces the chances for a drug to penetrate the cell to kill it. Inhibiting MurJ, however, would require getting past just one of the two membranes, meaning it could be an attractive new target for antibiotics in this age of resistant pathogens.
“We have proof of principle that MurJ is actually a valid target because we showed that if we stop it from working, the cells will die within 10 minutes – very quickly,” said Natividad Ruiz, assistant professor of microbiology at The Ohio State University and a co-lead author of the study.
“If you want to develop an antibiotic, it is important to know a protein’s function. Defining the activity associated with MurJ is a big step forward toward possibly designing antibiotics that could target it.”
Ruiz co-led the study with Thomas Bernhardt, associate professor of microbiology and immunobiology at Harvard Medical School. The research is published in the July 11, 2014, issue of the journal Science.
This work zeroes in on trying to stop construction of a bacterial cell layer called peptidoglycan, a mesh-like structure that, in gram-negative bacteria like E. coli, rests between the inner and outer cell membranes. Without this layer, E. coli cells can’t survive.
Scientists have long known most of the steps behind the creation of this layer, which consists of sugars and amino acids cross-linked with each other. But one detail has remained elusive: which protein could get a specific lipid required for building the peptidoglycan layer to change its location, from the inside of the inner membrane to the outside of that membrane, where the peptidoglycan construction is under way.
Lipids contain fat and other substances and serve as part of a cell membrane’s infrastructure. The mystery protein has been referred to as a flippase because of its function: flipping the lipid.
About 25 years ago, other groups of scientists proposed two likely proteins that fulfilled this role based on their locations in the bacterial cell. The proteins were known to contribute to construction of the peptidoglycan, but their specific function was never demonstrated.
While investigating cell membranes as a postdoctoral researcher, Ruiz narrowed in on the potential of the MurJ protein to serve as the E. coli flippase.
Ruiz and colleagues have previously shown that MurJ has several features that point to this possibility: A model of its structure shows the characteristic cavity that a flippase needs to have; eliminating the protein showed that cells wouldn’t make the peptidoglycan layer; and it was demonstrated to be related to other flipping proteins.
In this new work, the labs led by Ruiz and Bernhardt combined to take the additional steps needed to confirm MurJ’s function.
One step that was important to Ruiz was being able to stop MurJ’s work in the cells and see the immediate effects of that inhibition. With most research like this, scientists lower protein levels by suppressing activation of the genes that make the protein – which takes time and doesn’t necessarily fully eliminate the protein’s presence.
Ruiz’s lab instead used a synthetic chemical to bind to hotspots on MurJ in cells in ways that immediately stopped the protein from functioning.
“The idea is to inhibit the protein, and then – boom – analyze it and see whether you’re stopping the flipping,” Ruiz said. “It is the equivalent to using an antibiotic that would kill the protein by not allowing it to work when it binds.”
Bernhardt’s lab then developed a way to further test the effects of inhibiting MurJ. The researchers used a toxin some cells release that is known to “eat” the flipped lipid shortly after it appears on the outside of its inner membrane, effectively halting construction of the peptidoglycan.
In normal cells, very little of the target lipid could be detected when the toxin was inserted into the cells, meaning the lipid was being flipped and immediately consumed by the toxin. But when MurJ was inhibited in those cells and the toxin was added, the scientists detected a buildup of the lipid that the toxin could not eat – meaning that the lipid never got flipped because the activity of MurJ was gone.
“We showed these cells will die if we inhibit MurJ and we showed that MurJ is required for flipping to occur. If the cells are dying because the flipping doesn’t occur, then nobody else is doing that job. This is the one,” Ruiz said, explaining that MurJ is the mystery flippase.
This research was supported by funds from the American Heart Association and the National Institutes of Health.
Additional co-authors are Lok-To Sham of Harvard Medical School, Emily Butler of Ohio State’s Department of Microbiology, and Matthew Lebar and Daniel Kahne of Harvard University.
See you soon. Jeanne