Over the past few years, people have generally become more conscious about the food they consume. Thanks to easier access to information as well as public health campaigns and media coverage, people are more aware of how nutrition ties in with both health benefits and chronic diseases. As a result, there is an ongoing cultural shift in most countries, with people prioritizing eating healthily. In turn, the demand for healthier food options and nutritional supplements is steadily growing.

In line with these changes, Assistant Professor Kyohei Yamashita from Tokyo University of Science (TUS), Japan, has been studying a promising “superfood” called Euglena gracilis for over half a decade. A species of edible microalgae, E. gracilis has a rich nutritional profile, with a unique combination of vitamins, fibers, lipids, and proteins. Like most other photosynthetic plants, E. gracilis also contains carotenoids — natural substances with a wide variety of health benefits.

In a study published in 2023, a research team from TUS found a simple method to efficiently grow E. gracilis in an inexpensive medium (solid or liquid that contains nutrients and is used to grow bacteria) based on tomato juice. Now, in a new study, the researchers have explored a promising technique to make cultured E. gracilis produce carotenoids at a higher rate, rendering it even more nutritious. This study, which was co-authored by Dr. Kengo Suzuki from Euglena Co., Ltd., as well as Professor Tatsuya Tomo and Professor Eiji Tokunaga from TUS, was published in Volume 13, Issue 4 of the journal Plants in February 12, 2024.

The proposed approach is quite straightforward, and so is its rationale. When a plant is exposed to high-intensity light for extended periods of time, it undergoes a light-stress response. This, in turn, can cause the organism to produce molecules that protect it from further light exposure, including carotenoids. Based on these facts, the researchers investigated whether they could induce such a reaction in E. gracilis to enhance its carotenoid content ratio.

To this end, the team ran a series of experiments on multiple batches of cultured E. gracilis. They exposed cultures to light of different wavelengths (or colors) and at different intensities looking for a “reddening reaction,” which is a tell-tale sign of higher carotenoid production in many plant species. Moreover, they also tested a new culture medium based on bonito stock, a soup stock extracted from Katsuobushi, a traditional Japanese dish made from smoked bonito fish.

Interestingly, the researchers found that strong red-light irradiation at 605-660 nm triggered a reddening reaction in E. gracilis when cultured in bonito stock. They also looked at the chemical profiles of the cultures using high-performance liquid chromatography, both at the culture and single-cell level. These analyses revealed that reddened cells not only had a high concentration of diadinoxanthin, the most abundant carotenoid in E. gracilis, but also produced an unidentified xanthophyll-type carotenoid. On top of these, the team also noted that bonito stock cultures grew quicker and reached higher densities than cultures grown on conventional media, and likely produced more types or amounts of carotenoids.

Together, the results of this study could pave the way for an innovative and easily scalable technique for growing nutritious E. gracilis. The method’s simplicity is certainly one of its strengths, as Dr. Yamashita remarks, “Our approach does not involve genetic modifications and could thus be readily adopted by the food industry to expand the use of E. gracilis, both in food and as a nutritional supplement.” Notably, bonito stock is a nutritious food and using it in the culture medium would, therefore, provide additional health benefits.

Aside from its benefits to us humans, growing E. gracilis can also help the environment. “E. gracilis cultivation, which requires relatively few resources, can be a sustainable food resource,” explains Dr. Yamashita. “Our research marks an important step toward the development of new food technologies that contribute to people’s lives from both health and environmental perspectives.“

With the carotenoid market poised to become a multi-billion-dollar industry by 2030, this study will help deepen our understanding of carotenoid biosynthetic pathways, hopefully leading to the development of sustainable practices in the production of nutritional supplements and emerging foods.

Bacterial infections pose significant challenges to agriculture and medicine, especially as cases of antibiotic-resistant bacteria continue to rise. In response, scientists at Texas A&M AgriLife Research are elucidating the ways that bacteria-infecting viruses disarm these pathogens and ushering in the possibility of novel treatment methods.

In their recent study published in Science, Lanying Zeng, Ph.D., a professor, and Junjie Zhang, Ph.D., an associate professor, both in the Texas A&M College of Agriculture and Life Sciences Department of Biochemistry and Biophysics, detailed a precise mechanism by which phages disable bacteria.

The collaborative effort also involved:

• Yiruo Lin, Ph.D., research assistant professor in the Texas A&M College of Engineering Department of Computer Science and Engineering.
• Matthias Koch, Ph.D., assistant professor in the Texas A&M College of Arts and Sciences Department of Biology.
• Zemer Gitai, Ph.D., and Joshua Shaevitz, Ph.D., professors in the Princeton University Department of Molecular Biology and Department of Physics, respectively.
• Yinghao Wu, Ph.D., associate professor in the Albert Einstein College of Medicine Department of Systems and Computational Biology.

Together, the team worked to explain a series of interactions scientists have sought to understand since the early 1970s.

The need for new treatments

Pseudomonas aeruginosa is a type of bacteria that can cause infections in the blood, lungs and occasionally other parts of the body. These infections are especially common in healthcare settings, which often encounter drug-resistant bacteria. According to the Centers for Disease Control and Prevention, there were over 30,000 cases of multi-drug resistant P. aeruginosa infections among hospitalized patients in 2017.

The prevalence of antibiotic-resistant Pseudomonas infections makes them a practical point of focus for phage therapy, a type of treatment method using bacteriophages, or phages, that researchers at the Texas A&M Center for Phage Technology are exploring as an alternative to typical drugs.

Zeng and Zhang, co-directors at the center along with Jason Gill, Ph.D., associate professor in the Department of Animal Science, are exploring the usefulness of phages, even beyond phage therapy, by diving into the structures and mechanisms at play.

Targeting the pilus

One of the factors that allows P. aeruginosa to transmit antimicrobial-resistant genes among each other, as well as move around and create difficult-to-treat structures called biofilms, is an appendage called a pilus, named after the Latin word for spear. These cylindrical structures extend from the surface of bacteria.

Some phages make use of bacterial pili by attaching to them and allowing bacteria to reel the phage to the surface, where the phage can start infecting the bacteria.

In their study in Science, co-first authored by Texas A&M graduate students Jirapat Thongchol and Zihao Yu, the researchers studied this process step by step using fluorescence microscopy, cryogenic-electron microscopy and computational modeling. They observed how a phage called PP7 infects P. aeruginosa by attaching to the pilus, which then retracts and pulls the phage to the cell surface.

At the point of entry for the virus, the pilus bends and snaps off, and the loss of the pilus makes P. aeruginosa much less capable of infecting its own host.

Ongoing research

This work is a continuation of previous research published in 2020, when Zeng’s team found a phage that can similarly break off the pili of E. coli cells, preventing the bacteria from sharing genes among each other — a common way that antibiotic resistance spreads.

From left to right: Lanying Zeng, Ph.D., Junjie Zhang, Ph.D., Zihao Yu and Jirapat Thongchol. Along with others, these researchers at the Texas A&M Center for Phage Technology are searching for solutions to antibiotic-resistant bacterial infections and characterizing phage-bacterium interactions. (Zihao Yu/Texas A&M AgriLife)

The Science study on Pseudomonas is part of the team’s recent suite of research studies. Last month, they published findings in Nature Communications on the interaction between another genus of bacteria, Acinetobacter, and a phage that infects it. Another study, expected to be published next month, will cover a third genus of bacteria and additional phage.

The team’s progress in determining precise protein structures and molecular interactions has been made possible with AgriLife Research’s new cryo-electron microscope, which opened at Texas A&M at the end of 2022 and can resolve structures at the atomic level.

“In our earlier study on E. coli, we did not really explore much about the mechanism,” Zeng said. “In our study of Pseudomonas, we were able to explain much more about what exactly is going on, including the force and speed of pilus detachment, and understand why and how this happens.”

Uses in medicine

The implications of this ongoing research could prove to be important in treating antimicrobial infections. Zhang said doctors wouldn’t need to use phages to kill the bacteria — as is done in phage therapy — but could simply allow the viruses to disarm the bacteria, which may give the immune system the chance to fight the infection on its own or allow doctors to treat patients with lower doses of antibiotics.

“If you simply kill the bacteria, you break the cells, and they’re going to release toxic material from inside the cell into the host,” Zhang said. “Our approach is to use a particular type of phage that disarms the bacteria. We remove their ability to exchange drug-resistance genes or to move around by breaking off this appendage.”

The team of phage scientists said they will continue looking for similar instances of phages dampening the virulence of pathogenic bacteria.

“We’re taking a synergistic approach,” Zhang said. “We’re trying to understand a universal mechanism for this type of phage and how they’re capable of affecting other types of bacteria. That’s the overall aim of our collaborative effort: to try to tackle the problem of multi-drug resistant bacteria.”

At first glance, the star of the new study may not seem particularly impressive: only a few centimetres long, Platynereis dumerilii is a species of polychaete worm that can be found in temperate to tropical coastal waters around the globe; if your goal is to find outstanding animal personalities, surely there are better suited candidates. But that wasn’t the primary goal of the study, which experts from the AWI, the Max Perutz Labs in Vienna, the Universities of Vienna and Oldenburg, and the Katholieke Universiteit Leuven in Belgium contributed to. First and foremost, the researchers were interested in the internal clocks that dictate countless organisms’ daily rhythms.

“Biological timing is important at a number of levels,” explains Kristin Tessmar-Raible, a biologist at the AWI. “The ecological ties between species depend just as much on it as they do on biochemical processes at the cellular level.” But how do organisms’ internal clocks react when human beings warm the climate or use artificial light to turn night into day? “When it comes to marine organisms, we still know very little,” says Sören Häfker, the study’s main author. In this regard, rhythms are especially important in their lives: temperature, available light and food, and various other factors change throughout the day, and the organisms have to respond accordingly. They adapt their behaviour, metabolism, and genetic activity to these external rhythms.

However, it remains unclear whether they’ll be equally successful at doing so in the future. And when their internal clocks no longer match their environment, it can become a matter of survival. “As such, we need a much better understanding of how the rhythms of the oceans are changing and what it will mean for individual species and populations,” the biologist stresses — which means there’s a wealth of reasons to take a closer look at the daily behaviour of Platynereis dumerilii. In fact, for chronobiology, which focuses on organisms’ internal clocks, this distant relative of the dew worm has become one of the most important model species.

In past experiments, the team had noticed how the worms had quite disparate daily rhythms. Among human beings, it’s a familiar phenomenon: early birds rarely turn into night owls, and vice versa. But what about in marine polychaete worms? Are their behavioural differences just random variations or do they also have a personal tact? To find out, the group systematically observed the worms’ daily activities when there was a new moon. What they saw: some individuals became active at exactly the same time every night. In turn, others appeared to be arrhythmic “couch potatoes” that were only occasionally active — plus, there were various “shades of grey” between these two extremes. When the same worms were observed again several weeks later, their behaviour remained largely unchanged: once a couch potato, always a couch potato. “We were very surprised to see how reproducible the individual behavioural rhythms were,” says Tessmar-Raible. “This shows us that even worms have tiny, rhythmic personalities, so to speak.”

More individuality = more resiliency

To gain further insights into these behavioural differences, the group systematically compared the genetic activity in the heads of worms prone to particularly rhythmic and arrhythmic behaviour. Surprisingly, they found that the daily internal clock worked perfectly fine in all specimens, even the arrhythmic “couch potatoes,” and that the number of genes with rhythmic activity was nearly as high as in the “punctual” worms. The wide range of strategies they employ could offer the worms an evolutionary edge, as the experts surmise. After all, they live in a coastal environment with highly variable conditions; as such, lifestyle A might be the best choice for a given spot, while not far away, lifestyle B might be a better fit. In addition, this form of individuality could make them more resilient to major anthropogenic changes — in a transforming world, this diversity increases the chances of at least some worms being able to cope with their new circumstances.

But the study doesn’t just offer new insights into marine rhythms; it also underscores the fact that the processes at work within a given organism aren’t necessarily reflected in its behaviour: even among the couch potato worms, the genetic activity follows a daily rhythm, even if it’s not externally recognisable. And that’s likely true not just for worms, but for human beings as well. “That’s why such findings are also exciting for fields like chronomedicine,” says Tessmar-Raible.

In recent years, there have been intensified and successful efforts to bear patients’ individual daily rhythms in mind in the context of treating them. But, just as with the worms observed, they consist of various components, ranging from behaviour to genetic activity, which can react differently to medications and the timing of when they are administered. Accordingly, especially when it comes to human beings, it is important for chronomedical analyses to consider several different levels — if even worms can be so individualistic, our species is likely no exception.