Rings of power – how bacteria use circadian clocks to colonise their world

John Innes Centre

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Rings of bacterial colony growth controlled by circadian rhythms

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Credit: Dr Jack Dorling

Research has revealed how bacteria rely on circadian clocks to control the spread of their multi-cellular colonies.

The findings provide important clues as to how we might improve soil health and plant growth. They may also help to explain how some bacteria spread hospital-acquired infections.

Researchers at the John Innes Centre, University of Munich, and Leiden University made the discovery while studying the widespread soil bacterium Bacillus subtilis.

Circadian clocks, or circadian rhythms, align biological processes with the 24-hour solar cycle of life on earth. The circadian clock regulates much of our physiology and behaviour, for instance determining if we sleep earlier or later than others.

The European consortium discovered that circadian clocks exist in B. subtilis, which is one of the first examples of these cellular timepieces being found in a non-photosynthetic bacterium. Labs in the USA and Argentina discovered clocks in bacteria that associate with humans,  indicating that circadian clocks are found broadly in this ancient and diverse class of organisms.

Despite these breakthroughs, little was known about how the circadian clock worked to organise colonies of bacteria.

In research appearing in Nature Communications, the team used a range of experiments which strongly support the theory that the circadian clock acts as a master regulator controlling expression of diverse genes and the rate at which the bacterial colonies expand. Gene expression across colonies shows similarities with circadian control of multi-cellular organisms such as plants and animals.

To make this discovery, the team analysed colonies of B. subtilis expanding across plates of agar gel. They had noticed that B. subtilis forms concentric rings as it spreads on petri dishes, resembling the rings of decay caused by fungi on autumn apples.

In constant conditions, the team observed that the bacterial colony spread at the rate of one ring over each period of 24 hours.

They devised a set of experiments which alter environmental conditions such as light wavelength (blue and red light) and temperature. This allowed them to test if the pattern of bacterial development and gene expression might change in response to these external stimuli or if it maintains a 24-hour cycle – indicative of a self-sustained and internally driven clock.

The team observed that concentric rings formed at the edge of the colony about once a day under all sets of conditions, consistent with circadian timing.

In further experiments, the team used a luciferase reporting technique, involving a bioluminescent enzyme, that enables tracking of gene expression over time and space.

Imaging of bioluminescence showed that genes involved in the formation of biofilms, the slimy material that binds communities of bacteria together, were clearly expressed at very specific and individual times of day over a 24-hour period, as were genes involved in sporulation, a process where cells enter dormancy.

“We found that the clock organises the Bacillus subtilis colonies, the rate at which the colony spreads across petri dishes, and it structures patterns of gene expression according to the time of day,” said the first author of the study Dr Jack Dorling, postdoctoral scientist at the John Innes Centre.

“Bacillus subtilis is a soil bacterium that is also associated with plants. We think that bacterial circadian clocks organise the ecology of soil microorganisms and could have roles in supporting plant growth,” he added.

The European Research Council-funded consortium behind this research, MicroClock, is conducting experiments to identify the mechanisms of the Bacillus subtilis clock and how this impacts the ecology and evolution of the bacterium.

The research is testament to the blend of skills brought together in this European consortium which includes researchers at the John Innes Centre, University of Munich and Leiden University.

“This is an example of a big European team working in a synergistic way across several labs. We have developed techniques, resources and protocols by sharing the work across this multi-disciplinary team over a period of ten years,” said Professor Antony Dodd, a Group Leader at the John Innes Centre and a corresponding author of the paper.

The evolutionary distance between B. subtillis and the two species of human-associated bacteria reported to have clocks (Klebsiella aerogenes and Acinetobacter baumanii) suggests that circadian clocks could be widespread amongst non-photosynthetic bacteria and the biological domain of the prokaryotes.

This opens a new field of exploration for the field of chronobiology with benefits for biotech and human medicine.

Professor Martha Merrow at the University of Munich said, “Our aim is to describe the ‘how’s’ and ‘why’s’ of the circadian clock in this bacterium so that others will be able to more easily find circadian clocks in the thousands of other bacteria. We do not think that Bacillus is alone with their rhythms!”

In addition to the longer-term applications, this study has helped to change perceptions of how bacteria survive and thrive in the world around us, explains Professor Dodd.

“People tend to think of bacteria as these single cells that float around, but microbiologists know that they are part of a matrix held within a biofilm. Once you know this you can see bacteria as a multi-cellular structure and, thanks to this work, we have in Bacillus subtilis a scientific model for the study of circadian clocks across multi-cellular life.” 

The Bacillus subtilis circadian clock coordinates intricate spatiotemporal organisation, is in Nature Communications.

 

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Journal

Nature Communications

DOI

10.1038/s41467-026-74082-0 

Subject of Research

Not applicable

Article Title

The Bacillus subtilis circadian clock coordinates intricate spatiotemporal organisation

Article Publication Date

18-Jun-2026

 

New paths for developing drought-resistant crops

Ruhr-University Bochum

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Christopher Grefen and Khushbu Kumari are conducting laboratory research into how plants develop stomata. 

 

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Credit: © RUB, Marquard

Enzyme becomes active early in development

Stomata are microscopic pores on the surface of the lead through which plants take in carbon dioxide and release water. Their function depends on two guard cells that open and close in response to environmental signals. The research team in Bochum discovered that GELP80 becomes activated in an early stage of development and selectively reshapes the cuticular lipid structure surrounding the created pores. This gives the guard cells their mechanical flexibility required for later regulation of the pore opening.

Unusual shape and stiffer guard cell walls

Plants lacking both GELP80 and GELP100 developed abnormally shaped stomata with structurally defective cuticular ledges and stiffer guard cell walls. As a result, the stomata were restricted in their mobility. At the same time, however, the plants continued to react normally to abscisic acid (ABA), confirming that the cause of the defects does not lie in disrupted signal transmission, but rather in altered mechanical characteristics of the cell wall and cuticle.

Limited mobility is an advantage

Surprisingly, the limited mobility of the stomata under drought-induced stress proved advantageous: The mutant plants lost less water and survived longer drought periods much more often than wild type plants. After 14 days without water, their survival rate was at about 80 percent, whereas nearly all of the comparison plants died.

The team also established a new model for stomata development in which GELP80 orchestrates early cuticle organization while the guard cells are in their early development. Later, the related enzyme OSP1 enables final pore opening, revealing a precisely timed sequence of lipid-remodeling events required for functional stomata formation.

“GELP80 acts like a molecular sculptor at the stomatal pore—it remodels the cuticular lipids early in guard cell development to give the stomata the precise mechanical flexibility they need to function,” says Dr. Khushbu Kumari, first author of the study. “When that sculpting is lost, the pore architecture becomes rigid and disorganized, and the plant simply cannot open and close its stomata efficiently.”

For the first time, the findings reveal a direct link between lipid metabolism, cell wall mechanics, and stomatal physiology. As we are faced with increasing drought and water scarcity, this insight could aid in optimizing crops for better water management and greater resilience to drought.

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Journal

The Plant Cell

DOI

10.1093/plcell/koag150 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Lack of GDSL motif–containing proteins increases drought tolerance by altering the stomatal cuticle in Arabidopsis

 

The "water-saving" effect of vegetation under rising CO₂ may be overestimated

Institute of Atmospheric Physics, Chinese Academy of Sciences

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Direct and indirect pathways through which CO2 physiological effects (PHY) influence evapotranspiration.

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Credit: Xing Yuan

Climate warming is intensifying terrestrial water scarcity and drought risks worldwide. Meanwhile, rising atmospheric CO2 reduces plant stomatal conductance— the openness of leaf pores that governs both CO₂ intake and water loss — and improves water-use efficiency, which has been widely considered capable of alleviating land surface drying. However, a recent study reveals that this perceived benefit may have been optimistically overestimated.

 

On June 24, the team led by Prof. Xing Yuan published a paper in PNAS, uncovering a critical indirect impact that substantially limits the water-saving potential of vegetation under elevated CO2, originating from atmospheric feedbacks.

 

Based on simulations from Earth system models participating in CMIP6-C4MIP (the carbon-cycle climate intercomparison project within the global CMIP6 modeling framework),  the research team isolated the indirect impacts of vegetation changes on evapotranspiration through atmospheric feedbacks, and found that vegetation responses to rising CO2 (including increased leaf area and reduced stomatal conductance) can alter surface energy balance, leading to warming and enhanced atmospheric evaporative demand, which ultimately drives greater surface water loss, undermining the water savings they were expected to deliver.

 

This previously overlooked indirect impact offsets 54% of the vegetation water-saving effect in northern mid-to-high latitudes under current climate conditions, and this ratio is projected to increase to 68% under a future 4×CO2 scenario. Most concerning, at high latitudes, the net CO2 physiological effect on evapotranspiration becomes statistically insignificant, meaning the anticipated water-saving benefit essentially disappears.

 

The indirect impacts of vegetation changes exhibit strong latitudinal differences, with particularly pronounced effects in northern mid-to-high latitudes. In these regions, sustained water loss associated with atmospheric feedbacks can undermine the potential benefits of vegetation in mitigating land surface water scarcity, covering major agricultural regions such as the U.S. Corn Belt, European plains, and rice-growing regions of China.

 

As droughts become more frequent under climate change, vegetation’s role in regulating land surface water availability is becoming increasingly critical for agricultural production and water resource management. However, “the study warns against overreliance on CO2 physiological effects as a natural solution to drought,” said the corresponding author, Prof. Xing Yuan.

 

Meanwhile, in low-latitude regions, the first author Yi Hao noted that “although CO2 physiological effects may partially alleviate soil moisture drought, increasing compound heat and atmospheric drought stress are more likely to threaten ecosystem sustainability.”

 

The findings highlight that vegetation's CO₂ response alone cannot secure water resources or ecosystem stability under future climate change, underscoring the need for proactive adaptation strategies — including improved irrigation efficiency, drought-resilient crop breeding, and sustainable water resource planning.

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Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2534643123 

Article Title

A potential overestimation of CO2 physiological effects on evapotranspiration

Article Publication Date

22-Jun-2026

 

C'mon and join the convoy: Batteries, fuel cells would overhaul emissions from semis, other heavy vehicles

University of Michigan

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Although electrified versions of vans, buses and semis cost more upfront on average than their diesel-powered counterparts, the overall calculus behind adopting greener vehicles is currently in flux. 

The cost of diesel fuel is skyrocketing. California, where the new Tesla Semi is establishing a toehold, has also unveiled a rebate program to help companies purchase electric medium- and heavy-duty trucks. Plus, even as the federal U.S. government embraces fossil fuels, some companies remain committed to their sustainability goals, as evidenced by Amazon's ever-growing fleet of electric delivery vehicles.

Now, research from the University of Michigan shows just how big a difference switching from diesel to fuel cells or batteries can make when it comes to greenhouse gas emissions. If a medium- or heavy-duty battery electric vehicle were to be powered completely by renewable energy, it would offer around a 90% reduction in lifetime greenhouse gas emissions compared to its diesel equivalent.

The research team, led by Maxwell Woody and Greg Keoleian, published its results in the journal Nature Energy and was supported by the Ford-University of Michigan Alliance Program.

"There's an urgency for climate action and to reduce greenhouse gas emissions from the transportation sector," said Keoleian, a professor at the U-M School for Environment and Sustainability, or SEAS. "There's a disproportionate amount of emissions from these heavy- and medium-duty vehicles compared to the rest of the vehicles on the road."

Medium- and heavy-duty vehicles account for nearly 30% of road vehicle emissions despite making up just about 5% of traffic on U.S. roadways, according to the U.S. Department of Energy.

"Moving to battery electric vehicles and even hydrogen fuel cell vehicles provides a significant reduction in emissions," said Keoleian, who is also co-director of U-M's Center for Sustainable Systems, or CSS.

This study, focusing on larger vehicles, follows a comprehensive study from the team that showed electrified sedans, SUVs and light-duty pickups reduced lifetime emissions from noncommercial vehicles across the U.S. In the new study, the team performed life cycle analyses for Class 3 vehicles, weighing between 10,001 and 14,000 pounds, up to Class 8 vehicles that can weigh up to 80,000 pounds. 

They modeled different powertrains, including internal combustion engines, hybrids, battery-powered EVs and fuel cell electric vehicles, accounting for a variety of other factors. That included variables like how a vehicle was driven—for example, with the frequent starts and stops of urban delivery up to the long-haul drives of trucks with sleeper cabs. The researchers also examined how hydrogen and electrons for fuel cells and batteries, respectively, were sourced, comparing established methods to newer, greener options. 

In the case of fuel cells, this meant analyzing sourcing hydrogen from the standard process known as steam methane reforming versus greener hydrogen from the electrolysis of water powered by renewables. For battery electric vehicles, the standard is simply plugging into the current grid versus charging from renewables alone.

Though there were variations due to these factors, a clear takeaway emerged: Hydrogen fuel cells and battery electric powertrains offered the largest lifetime emissions reductions compared with diesel-powered vehicles. 

• Battery electric vehicles cut emissions by 72%-82% using the current grid and by 87%-92% using renewables only.
• Fuel cells offered 12%-51% reductions using steam methane reforming and 44%-68% reductions with electrolysis powered by renewables.
• Hybrid powertrains offered 1%-26% emission reductions.

"Basically, we see across all the different vehicle sizes the same general pattern of the conventional diesel having the highest emissions, then the hybrid, then the fuel cell with conventional hydrogen production, then the battery electric with grid electricity, then  fuel cell with green hydrogen, and then the battery electric vehicle with renewable electricity," said Woody, a postdoctoral researcher with CSS. "That pattern held across everything that we investigated, from the Class 3 van to the Class 8 truck." 

SEAS doctoral student Spencer Checkoway also contributed to the research, as did Robert De Kleine, Hyung Chul Kim and James Anderson at Ford Motor Co.

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Journal

Nature Energy

DOI

10.1038/s41560-026-02095-6 

Article Title

Batteries vs Fuel Cells for Decarbonizing Medium- and Heavy-Duty Vehicles Across Applications

Article Publication Date

25-Jun-2026

 

Where nature conservation can make the greatest difference in saving endangered species

Linköping University

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Karl-Olof Bergman, senior associate professor at Linköping University.

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Credit: Charlotte Perhammar/Linköping University

Old oak trees and semi-natural grasslands are very important for a large number of species that risk disappearing as habitats decline. In a new study, researchers at Linköping University in Sweden present their findings on the habitat amount needed. The results can help nature conservation agencies set scientifically based goals and take more precise action to ensure long term survival of threatened species.

No less than 1,800 species are associated with the oak. This makes the oak the most biodiversity-rich tree in Sweden. Together with semi-natural grasslands, oak landscapes play an important role in enabling species to form viable populations that survive in the long term. But how much of these types of habitat is needed?

It would be practically impossible for researchers to physically count every animal and plant at each site. Instead, they used a combination of private databases, various species projects and the digital reporting system Artportalen, a platform for open public reporting of species sightings. The researchers behind the study combined millions of reported species data with data on habitat distribution, such as inventories of large oaks made by county administrative boards, and other openly available geodata on grasslands. By combining data on species found with habitat data, the researchers were able to search for patterns.

The researchers show that the amount of habitat is linked to whether different species occur at a given location. They were also able to identify thresholds for how much habitat is needed for a species to persist.

“A sensitive species is more likely to be found in an oak-rich landscape than in a place where there are very few oaks. We’ve been able to calculate threshold values for different species. We can with relatively high confidence provide a target for how much habitat is needed,” says Karl-Olof Bergman, senior associate professor at Linköping University, who led the study published in the journal Landscape Ecology.

One of the most discerning species, which needs many old oaks in its vicinity, is the orange polypore Aurantiporus croceus; a globally endangered fungus species that is critically endangered in Sweden. In their study, the researchers identified how much habitat is required for the species to be found in a particular location. And if the orange polypore can grow there, the requirements are also met for all other species dependent on old oaks. The results provide conservationists with concrete, science-based data to prioritise cost-effective interventions where they are most useful.

“It’s particularly important that we can identify areas where endangered species occur today, but where habitats are too small or fragmented for the species to survive long-term. Species richness in these places exists on borrowed time. We have a time window now when we can act and restore these environments to save species that will otherwise disappear from there,” says Karl-Olof Bergman.

But why does it matter if we lose species such as the orange polypore? The answer lies in how deeply interwoven biodiversity is with our own everyday lives. Functional, species-rich ecosystems are a prerequisite for the existence of clean water, clean air and productive soils. Some fruits and vegetables are highly dependent on pollination by various insects to provide good harvests. Many pharmaceuticals are based on substances found in plants and animals, and even today new discoveries are being made that may come to benefit humans in the future.

“The utility perspective is important, but everything in nature has an intrinsic value. What right do we have to eradicate species that have millions of years of evolution behind them? The species that disappear during our lifetime are also lost for all future generations,” says Karl-Olof Bergman.

The study was conducted in collaboration with the Pro Natura enterprise foundation and was funded by WWF Sweden and Formas.

Article: Identifying functional landscapes in Sweden for semi-natural grasslands and old-growth oaks (Quercus robur) based on habitat thresholds, Karl‑Olof Bergman, Leif Andersson, Markus Franzén, Victor Johansson and Lars Westerberg, (2026), Landscape Ecology, published online 22 May 2026, doi: https://doi.org/10.1007/s10980-026-02373-4

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Journal

Landscape Ecology

DOI

10.1007/s10980-026-02373-4 

Article Title

Identifying functional landscapes in Sweden for semi-natural grasslands and old-growth oaks (Quercus robur) based on habitat thresholds

 

Hantavirus in the South Atlantic: A one health and microbiome wake‑up call

KeAi Communications Co., Ltd.

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On 1 April 2026, the polar expedition cruise ship MV Hondius sailed from Argentina on a transatlantic voyage. By the middle of the month, passengers developed fever and breathing difficulties. The World Health Organization confirmed 11 hantavirus pulmonary syndrome (HPS) cases, including three deaths (27% fatality). Genomic sequencing identified Andes virus — the only hantavirus known to spread via limited human‑to‑human transmission.

No rodents were found aboard. The confined vessel, carrying 147 people from 23 countries, became an unexpected amplifier of person‑to‑person transmission. The ship had stopped at remote ecological hotspots including the Antarctic Peninsula and Tristan da Cunha. This is not an isolated incident — it is a clear ecological alert: global travel and environmental change are reshaping how zoonotic viruses emerge.

Microbiome and biodiversity matter

A recent study shows that hantavirus infection alters the lung microbiome of rodent reservoirs (Xiong et al., Microorganisms, 2026). Such changes could serve as early‑warning indicators of spillover risk. Meanwhile, long‑term evidence from Shaanxi, China, reveals that land consolidation reduced rodent diversity by 53%, creating a "one‑species monopoly" of the dominant hantavirus host. This dramatically accelerated viral transmission to humans — a powerful illustration of how land‑use change drives disease risk.

Four urgent actions

Professor Lu proposes four initiatives aligned with Microbiome and One Health:

1. Multi‑sectoral One Health coordination — integrating human, animal, environmental and climate expertise.

2. Microbiome surveillance — using reservoir host microbiota as early warning indicators.

3. Multi‑factor early warning systems — combining biodiversity, climate and travel data.

4. Ecologically informed travel health regulations — targeting cruise ships and ecotourism.

Concluding remarks

As this commentary went to press, WHO declared a new Ebola PHEIC (Public Health Emergency of International Concern). Ebola and hantavirus share strikingly similar ecological drivers: deforestation, climate anomalies and global travel networks. The 2026 Ebola PHEIC and the hantavirus cruise cluster are two fractures on the same One Health crisis map. The boundaries between human, animal and ecosystem health have effectively vanished.

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Contact the author:

Jiahai Lu

Institute of One Health, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, P.R. China

lujiahai@wmu.edu.cn

The publisher KeAi was established by Elsevier and China Science Publishing & Media Ltd to unfold quality research globally. In 2013, our focus shifted to open access publishing. We now proudly publish more than 200 world-class, open access, English language journals, spanning all scientific disciplines. Many of these are titles we publish in partnership with prestigious societies and academic institutions, such as the National Natural Science Foundation of China (NSFC).

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DOI

10.1016/j.mico.2026.100002 

Article Title

Hantavirus on the South Atlantic: A One Health and Microbiome Perspective on an Emerging Ecological Alert

 

New breeding techniques for plants: DFG welcomes European Parliament approval of new regulation

Deutsche Forschungsgemeinschaft

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The European Parliament has given its final approval in Brussels to a new legal framework for plants produced using new breeding techniques (new genomic techniques, NGTs). At second reading, Parliament adopted the regulation that were the subject of trilogue negotiations with the Member States and the European Commission in December 2025. The Council gave its final approval to the regulation in April 2026. The Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) welcomes this step, having actively advocated at European level for a reform of legislation governing genetic engineering in recent years.

The adopted regulation provides for simplified rules concerning so-called NGT-1 plants that could also have been produced using conventional breeding methods. These plants will no longer have to comply with the strict authorisation and labelling requirements that will continue to apply to other plants produced using new breeding techniques (NGT-2). In future, the EU will assess plants more based on their characteristics than on the breeding method used.

“Following the initial political breakthrough in December 2025, when the Council and Parliament arrived at a provisional agreement, we hoped for swift approval by the EU institutions in the interests of science,” said DFG President Prof. Dr. Katja Becker. “I’m delighted that this has now been achieved without further amendments. From mid-2028, when the regulation comes into force, researchers will now be able to conduct field trials much more easily, for example to improve plants’ resilience to climate change and resistance to pests. This will mean that new breeding techniques can become one of the tools for securing stable and increasing yields while reducing the use of pesticides.”

“In this way we can help safeguard food security, sustainability and adaptation to climate change in Europe,” added Prof. Dr. Axel Brakhage, Chair of the DFG Senate Commission on Genetic Research. He reiterated: “From a scientific perspective, genome-edited plants whose genetic modifications could also have arisen naturally or through conventional breeding techniques do not pose any specific risks. In our view, they can be treated in the same way as conventionally bred varieties.”

The classification of NGT-1 plants as adopted in the regulation reflects this scientific assessment, thereby overcoming the strictly process-based regulatory approach that has significantly restricted research and innovation to date. The newly adopted legal framework provides researchers and breeders in Germany and Europe with reliable prospects. It facilitates field trials, strengthens competitiveness and establishes the conditions for developing more robust, sustainably produced crops that can contribute to the objectives of the EU’s Vision for Agriculture and Food.


Further Information

Media contact:
 DFG Press and Public Relations, Tel. +49 228 885-2109, presse@dfg.de

For further information on the DFG Permanent Senate Commission on Genetic Research and its publications, see: www.dfg.de/sc_genetic_research