Phages, which are harmless viruses that destroy specific bacteria, are becoming useful tools to protect our food supply.
Food producers and packagers fight bacteria by potent chemicals, with chlorine being the go-to disinfectant. Cattle carcasses, for example, are typically washed by chlorine solutions as the animals' intestines are removed. Leafy greens are bathed in water with added chlorine solutions. However, because the same "bath" can be used for multiple veggie batches and chlorine evaporates over time, the later rounds may not kill all of the bacteria, sparing some. The natural and organic producers avoid chlorine, substituting it with lactic acid, a more holistic sanitizer, but even with all these efforts, some pathogens survive, sickening consumers and causing food recalls. As we farm more animals and grow more produce, while also striving to use fewer chemicals and more organic growing methods, it will be harder to control bacteria's spread.
"It took us a long time to convince the FDA phages were safe and efficient alternatives. But we had worked with them to gather all the data they needed, and the FDA was very supportive in the end."
Luckily, bacteria have their own killers. Called bacteriophages, or phages for short, they are viruses that prey on bacteria only. Under the electron microscope, they look like fantasy spaceships, with oblong bodies, spider-like legs and long tails. Much smaller than a bacterium, phages pierce the microbes' cells with their tails, sneak in and begin multiplying inside, eventually bursting the microbes open—and then proceed to infect more of them. The best part is that these phages are harmless to humans. Moreover, recent research finds that millions of phages dwell on us and in us—in our nose, throat, skin and gut, protecting us from bacterial infections as part of our healthy microbiome. A recent study suggested that we absorb about 30 billion phages into our bodies on a daily basis. Now, ingeniously, they are starting to be deployed as anti-microbial agents in the food industry.
A Maryland-based phage research company called Intralytix is doing just that. Founded by Alexander Sulakvelidze, a microbiologist and epidemiologist who came to the United States from Tbilisi, the capital of Georgia, Intralytix makes and sells five different FDA-approved phage cocktails that work against some of the most notorious food pathogens: ListShield for Listeria, SalmoFresh for Salmonella, ShigaShield for Shigella, another foodborne bug, and EcoShield for E.coli, including the infamous strain that caused the Jack in the Box outbreak in 1993 that killed four children and sickened 732 people across four states. Earlier this month, the FDA granted its approval to yet another Intralytix phage for managing Campylobacter contamination, named CampyShield. "We call it safety by nature," Sulakvelidze says.
Intralytix grows phages inside massive 1500-liter fermenters, feeding them bacterial "fodder."
Photo credit: Living Radiant Photography
Phage preparations are relatively straightforward to make. In nature, phages thrive in any body of water where bacteria live too, including rivers, lakes and bays. "I can dip a bucket into the Chesapeake Bay, and it will be full of all kinds of phages," Sulakvelidze says. "Sewage is another great place to look for specific phages of interest, because it's teeming with all sorts of bacteria—and therefore the viruses that prey on them." In lab settings, Intralytix grows phages inside massive 1500-liter fermenters, feeding them bacterial "fodder." Once phages multiply enough, they are harvested, dispensed into containers and shipped to food producers who have adopted this disinfecting practice into their preparation process. Typically, it's done by computer-controlled sprayer systems that disperse mist-like phage preparations onto the food.
Unlike chemicals like chlorine or antibiotics, which kill a wide spectrum of bacteria, phages are more specialized, each feeding on specific microbial species. A phage that targets salmonella will not prey on listeria and vice versa. So food producers may sometimes use a combo of different phage preparations. Intralytix is continuously researching and testing new phages. With a contract from the National Institutes of Health, Intralytix is expanding its automated high-throughput robot that tests which phages work best against which bacteria, speeding up the development of the new phage cocktails.
Phages have other "talents." In her recent study, Jaroni found that phages have the ability to destroy bacterial biofilms—colonies of microorganisms that tend to grow on surfaces of the food processing equipment, surrounding themselves with protective coating that even very harsh chemicals can't crack. "Phages are very clever," Jaroni says. "They produce enzymes that target the biofilms, and once they break through, they can reach the bacteria."
Convincing the FDA that phages were safe to use on food products was no easy feat, Sulakvelidze says. In his home country of Georgia, phages have been used as antimicrobial remedies for over a century, but the FDA was leery of using viruses as food safety agents. "It took us a long time to convince the FDA phages were safe and efficient alternatives," Sulakvelidze says. "But we had worked with them to gather all the data they needed, and the FDA was very supportive in the end." The agency had granted Intralytix its first approval in 2006, and over the past 10 years, the company's sales increased by over 15-fold. "We currently sell to about 40 companies and are in discussions with several other large food producers," Sulakvelidze says. One indicator that the industry now understands and appreciates the science of phages was that his company was ranked as Top Food Safety Provider in 2021 by Food and Beverage Technology Review, he adds. Notably, phage sprays are kosher, halal and organic-certified.
Intralytix's phage cocktails to safeguard food from bacteria are approved for consumers in addition to food producers, but currently the company sells to food producers only. Selling retail requires different packaging like easy-to-use spray bottles and different marketing that would inform people about phages' antimicrobial qualities. But ultimately, giving people the ability to remove pathogens from their food with probiotic phage sprays is the goal, Sulakvelidze says.
It's not the company's only goal. Now Intralytix is going a step further, investigating phages' probiotic and therapeutic abilities. Because phages are highly specialized in the bacteria they target, they can be used to treat infections caused by specific pathogens while leaving the beneficial species of our microbiome intact. In an ongoing clinical trial with Mount Sinai, Intralytix is now investigating a potential phage treatment against a certain type of E. coli for patients with Crohn's disease, and is about to start another clinical trial for treating bacterial dysentery.
"Now that we have proved that phages are safe and effective against foodborne bacteria," Sulakvelidze says, "we are going to demonstrate their potential in therapeutic applications."
NASA astronaut Frank Rubio floats by the International Space Station’s “window to the world.” Yesterday, he returned from the longest single spaceflight by a U.S. astronaut on record - over one year. Exploring deep space will require even longer missions.
Yesterday, NASA astronaut Frank Rubio returned to Earth after over one year, the longest single spaceflight for a U.S. astronaut. But this is just the start; longer and more complex missions into deep space loom ahead, from returning to the moon in 2025 to eventually sending humans to Mars. To ensure that these missions succeed, NASA is increasing efforts to study the biological effects and prevent harm.
The dangers of microgravity are real
A NASA report published in 2016 details a long list of incidents and near-misses caused – at least partly – by space-induced changes in astronauts’ vision and coordination. These issues make it harder to move with precision and to judge distance and velocity.
According to the report, in 1997, a resupply ship collided with the Mir space station, possibly because a crew member bumped into the commander during the final docking maneuver. This mishap caused significant damage to the space station.
Returns to Earth suffered from problems, too. The same report notes that touchdown speeds during the first 100 space shuttle landings were “outside acceptable limits. The fastest landing on record – 224 knots (258 miles) per hour – was linked to the commander’s momentary spatial disorientation.” Earlier, each of the six Apollo crews that landed on the moon had difficulty recognizing moon landmarks and estimating distances. For example, Apollo 15 landed in an unplanned area, ultimately straddling the rim of a five-foot deep crater on the moon, harming one of its engines.
Spaceflight causes unique stresses on astronauts’ brains and central nervous systems. NASA is working to reduce these harmful effects.
NASA
Space messes up your brain
In space, astronauts face the challenges of microgravity, ionizing radiation, social isolation, high workloads, altered circadian rhythms, monotony, confined living quarters and a high-risk environment. Among these issues, microgravity is one of the most consequential in terms of physiological changes. It changes the brain’s structure and its functioning, which can hurt astronauts’ performance.
The brain shifts upwards within the skull, displacing the cerebrospinal fluid, which reduces the brain’s cushioning. Essentially, the brain becomes crowded inside the skull like a pair of too-tight shoes.
That’s partly because of how being in space alters blood flow. On Earth, gravity pulls our blood and other internal fluids toward our feet, but our circulatory valves ensure that the fluids are evenly distributed throughout the body. In space, there’s not enough gravity to pull the fluids down, and they shift up, says Rachael D. Seidler, a physiologist specializing in spaceflight at the University of Florida and principal investigator on many space-related studies. The head swells and legs appear thinner, causing what astronauts call “puffy face chicken legs.”
“The brain changes at the structural and functional level,” says Steven Jillings, equilibrium and aerospace researcher at the University of Antwerp in Belgium. “The brain shifts upwards within the skull,” displacing the cerebrospinal fluid, which reduces the brain’s cushioning. Essentially, the brain becomes crowded inside the skull like a pair of too-tight shoes. Some of the displaced cerebrospinal fluid goes into cavities within the brain, called ventricles, enlarging them. “The remaining fluids pool near the chest and heart,” explains Jillings. After 12 consecutive months in space, one astronaut had a ventricle that was 25 percent larger than before the mission.
Some changes reverse themselves while others persist for a while. An example of a longer-lasting problem is spaceflight-induced neuro-ocular syndrome, which results in near-sightedness and pressure inside the skull. A study of approximately 300 astronauts shows near-sightedness affects about 60 percent of astronauts after long missions on the International Space Station (ISS) and more than 25 percent after spaceflights of only a few weeks.
Another long-term change could be the decreased ability of cerebrospinal fluid to clear waste products from the brain, Seidler says. That’s because compressing the brain also compresses its waste-removing glymphatic pathways, resulting in inflammation, vulnerability to injuries and worsening its overall health.
The effects of long space missions were best demonstrated on astronaut twins Scott and Mark Kelly. This NASA Twins Study showed multiple, perhaps permanent, changes in Scott after his 340-day mission aboard the ISS, compared to Mark, who remained on Earth. The differences included declines in Scott’s speed, accuracy and cognitive abilities that persisted longer than six months after returning to Earth in March 2016.
By the end of 2020, Scott’s cognitive abilities improved, but structural and physiological changes to his eyes still remained, he said in a BBC interview.
“It seems clear that the upward shift of the brain and compression of the surrounding tissues with ventricular expansion might not be a good thing,” Seidler says. “But, at this point, the long-term consequences to brain health and human performance are not really known.”
NASA astronaut Kate Rubins conducts a session for the Neuromapping investigation.
NASA
Staying sharp in space
To investigate how prolonged space travel affects the brain, NASA launched a new initiative called the Complement of Integrated Protocols for Human Exploration Research (CIPHER). “CIPHER investigates how long-duration spaceflight affects both brain structure and function,” says neurobehavioral scientist Mathias Basner at the University of Pennsylvania, a principal investigator for several NASA studies. “Through it, we can find out how the brain adapts to the spaceflight environment and how certain brain regions (behave) differently after – relative to before – the mission.”
To do this, he says, “Astronauts will perform NASA’s cognition test battery before, during and after six- to 12-month missions, and will also perform the same test battery in an MRI scanner before and after the mission. We have to make sure we better understand the functional consequences of spaceflight on the human brain before we can send humans safely to the moon and, especially, to Mars.”
As we go deeper into space, astronauts cognitive and physical functions will be even more important. “A trip to Mars will take about one year…and will introduce long communication delays,” Seidler says. “If you are on that mission and have a problem, it may take eight to 10 minutes for your message to reach mission control, and another eight to 10 minutes for the response to get back to you.” In an emergency situation, that may be too late for the response to matter.
“On a mission to Mars, astronauts will be exposed to stressors for unprecedented amounts of time,” Basner says. To counter them, NASA is considering the continuous use of artificial gravity during the journey, and Seidler is studying whether artificial gravity can reduce the harmful effects of microgravity. Some scientists are looking at precision brain stimulation as a way to improve memory and reduce anxiety due to prolonged exposure to radiation in space.
Other scientists are exploring how to protect neural stem cells (which create brain cells) from radiation damage, developing drugs to repair damaged brain cells and protect cells from radiation.
To boldly go where no astronauts have gone before, they must have optimal reflexes, vision and decision-making. In the era of deep space exploration, the brain—without a doubt—is the final frontier.
Additionally, NASA is scrutinizing each aspect of the mission, including astronaut exercise, nutrition and intellectual engagement. “We need to give astronauts meaningful work. We need to stimulate their sensory, cognitive and other systems appropriately,” Basner says, especially given their extreme confinement and isolation. The scientific experiments performed on the ISS – like studying how microgravity affects the ability of tissue to regenerate is a good example.
“We need to keep them engaged socially, too,” he continues. The ISS crew, for example, regularly broadcasts from space and answers prerecorded questions from students on Earth, and can engage with social media in real time. And, despite tight quarters, NASA is ensuring the crew capsule and living quarters on the moon or Mars include private space, which is critical for good mental health.
Exploring deep space builds on a foundation that began when astronauts first left the planet. With each mission, scientists learn more about spaceflight effects on astronauts’ bodies. NASA will be using these lessons to succeed with its plans to build science stations on the moon and, eventually, Mars.
“Through internally and externally led research, investigations implemented in space and in spaceflight simulations on Earth, we are striving to reduce the likelihood and potential impacts of neurostructural changes in future, extended spaceflight,” summarizes NASA scientist Alexandra Whitmire. To boldly go where no astronauts have gone before, they must have optimal reflexes, vision and decision-making. In the era of deep space exploration, the brain—without a doubt—is the final frontier.
Swiss researchers have found a type of brain cell that appears to be a hybrid of the two other main types — and it could lead to new treatments for brain disorders.
A new brain cell: Researchers at the Wyss Center for Bio and Neuroengineering and the University of Lausanne believe they’ve definitively proven that some astrocytes do actively participate in neurotransmission, making them a sort of hybrid of neurons and glial cells.
According to the researchers, this third type of brain cell, which they call a “glutamatergic astrocyte,” could offer a way to treat Alzheimer’s, Parkinson’s, and other disorders of the nervous system.
“Its discovery opens up immense research prospects,” said study co-director Andrea Volterra.
The study: Neurotransmission starts with a neuron releasing a chemical called a neurotransmitter, so the first thing the researchers did in their study was look at whether astrocytes can release the main neurotransmitter used by neurons: glutamate.
By analyzing astrocytes taken from the brains of mice, they discovered that certain astrocytes in the brain’s hippocampus did include the “molecular machinery” needed to excrete glutamate. They found evidence of the same machinery when they looked at datasets of human glial cells.
Finally, to demonstrate that these hybrid cells are actually playing a role in brain signaling, the researchers suppressed their ability to secrete glutamate in the brains of mice. This caused the rodents to experience memory problems.
“Our next studies will explore the potential protective role of this type of cell against memory impairment in Alzheimer’s disease, as well as its role in other regions and pathologies than those explored here,” said Andrea Volterra, University of Lausanne.
But why? The researchers aren’t sure why the brain needs glutamatergic astrocytes when it already has neurons, but Volterra suspects the hybrid brain cells may help with the distribution of signals — a single astrocyte can be in contact with thousands of synapses.
“Often, we have neuronal information that needs to spread to larger ensembles, and neurons are not very good for the coordination of this,” researcher Ludovic Telley told New Scientist.
Looking ahead: More research is needed to see how the new brain cell functions in people, but the discovery that it plays a role in memory in mice suggests it might be a worthwhile target for Alzheimer’s disease treatments.
The researchers also found evidence during their study that the cell might play a role in brain circuits linked to seizures and voluntary movements, meaning it’s also a new lead in the hunt for better epilepsy and Parkinson’s treatments.
“Our next studies will explore the potential protective role of this type of cell against memory impairment in Alzheimer’s disease, as well as its role in other regions and pathologies than those explored here,” said Volterra.
