From palm oil to designer enzymes: Frankfurt researchers reprogram yeast cells

Protein engineering enables sustainable production of industrially important fatty acids

Goethe University Frankfurt

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Schematic representation of biosynthesis in a cell (top) and in the laboratory (bottom). The designer enzyme shortens the chain length of the fatty acid.

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Credit: Felix Lehmann & Martin Grininger/Goethe University

FRANKFURT. Whether laundry detergents, mascara, or Christmas chocolate – many everyday products contain fatty acids from palm oil or coconut oil. However, the extraction of these raw materials is associated with massive environmental issues: rainforests are cleared, habitats for endangered species are destroyed, and traditional farmers lose their livelihoods. The team led by Prof. Martin Grininger at Goethe University in Frankfurt, Germany, has now developed a biotechnological approach that could enable a more environmentally friendly production method.

 

A Molecular Assembly Line with Precise Control
At the heart of this research is an enzyme called fatty acid synthase (FAS) – a type of molecular assembly line that builds fatty acids in all living organisms. “FAS is one of the most important enzymes in a cell's metabolism and has been fine-tuned by evolution over millions of years,” explains Grininger.

 

The enzyme typically produces palmitic acid, a 16-carbon fatty acid that serves as a building block for cell membranes and energy storage. Industry, however, primarily requires shorter variants with 6 to 14 carbon atoms, which today are sourced from plant oils produced on large-scale oil palm plantations linked to deforestation and biodiversity loss. The decisive advantage of the new, FAS-based method: “Fundamentally, our advantage lies in the very precise control of chain length. We can theoretically make any chain length, and we're demonstrating this with the example of C12 fatty acid, which otherwise can only be obtained from palm kernels or coconut,” says Grininger.

 

Understanding Through Modification
Grininger and his team have significantly contributed to understanding the molecular foundations of FAS over the past 20 years. They discovered that chain length is regulated by the interplay between two subunits: ketosynthase repeatedly elongates the chain by two carbon atoms while thioesterase cleaves off the finished chain as a fatty acid. “We then asked ourselves whether we could go beyond analysis and build FAS with new chain length regulation,” says Grininger. “True understanding begins when you can change or customize a phenomenon.”

 

Two Targeted Interventions Lead to Success

Grininger’s doctoral student Damian Ludig took up this idea. “We asked what would happen if we specifically intervened in the interaction between these two subunits,” Ludig explains. “Could we then control the chain length of the fatty acids that are produced?”

 

Ludig employed protein engineering methods where individual amino acids can be exchanged or entire protein regions modified. “Two changes to FAS through protein engineering ultimately led us to our goal,” says Ludig. “In the ketosynthase subunit, I first exchanged one amino acid which resulted in chains being extended only with low efficiency beyond a certain length. Additionally, I replaced the thioesterase subunit with a similar protein from bacteria that shows activity in cleaving short chains.” Depending on further adjustments, Ludig was able to produce short- and medium-length fatty acids.

 

From Frankfurt to Dalian
Collaboration with Prof. Yongjin Zhou’s research group at Dalian Institute of Chemical Physics, Chinese Academy of Sciences, ultimately achieved breakthrough results. Supported by the German Research Foundation (DFG) and the National Natural Science Foundation of China (NSFC), Zhou and his lab succeeded in developing yeast strains that produce fatty acids containing only 12 carbon atoms instead of 16. Various designer FAS from Grininger's lab were integrated into these yeasts for optimization.

Both laboratories have already filed patents for their technologies. “On the Chinese side, Unilever was involved in this project. Our development has thus far taken place without industrial participation. However, we are striving for a collaboration with an industry partner in order to bring the technology into application,” says Grininger.

 

Thinking Ahead: From Fatty Acids to Pharmaceuticals
In a second project, Felix Lehmann from Grininger's lab took the research even further by investigating how universally applicable FAS are for tailored biosyntheses: “This question is also driven by necessity – to continually develop chemical processes towards more sustainable green chemistry,” explains Grininger.

 

The specific question was: Can FAS be redirected to make not only fatty acids, but also entirely different compounds, such as styrylpyrones? These molecules are precursors to substances derived from kava plants that attract medical interest due to their potential anxiolytic properties. Here, too, Lehmann achieved success with relatively few modifications: “First we cut away part of FAS that we didn't need for our target products; then we altered ketosynthase so that cinnamic acid could be used as starting material,” he explains. The team even integrated another protein into the FAS structure so it became part of multi-enzyme complex.

 

“In this project we systematically examined how entire biosynthetic pathways can be constructed with FAS from readily available building blocks,” Grininger explains. While the results do not yet have immediate practical applications, they provide important guidance for the future design of novel synthases.

 

At the Intersection of Chemistry and Biology
“Our lab has made significant strides towards biocatalysis and biotechnological applications over recent years, driven by the contributions of many projects and collaborations. We will continue down this path”, Grininger summarizes. “Within the Cluster of Excellence SCALE, we will also use this enzyme to generate tailored biomembranes, whose analysis will help deepen our understanding of key organelles such as the endoplasmic reticulum and mitochondria.”

 

Whether technology can indeed alleviate palm oil issues now depends on successful scaling up alongside industry partners. The scientific foundation has certainly been laid and the lab still has many ideas to explore.

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Journal

Nature Chemical Biology

DOI

10.1038/s41589-025-02105-w 

Method of Research

Experimental study

Subject of Research

Cells

Article Publication Date

7-Jan-2026

 

Like alcohol units, but for cannabis – experts define safer limits

Researchers propose threshold levels for cannabis use, aiming to help people monitor potency and quantity to reduce health risks.

University of Bath

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Researchers at the University of Bath in the UK are proposing thresholds for safe – or at least safer – cannabis use and hope their findings will help people monitor consumption and keep it within recommended limits – similar to how alcohol units guide safer drinking.

The threshold recommendations, proposed in a paper published today in the journal Addiction, are based on a system for measuring cannabis consumption not by weight but by THC content (THC is the compound responsible for the psychoactive effects of cannabis).

In the same way as guidelines for safer alcohol use focus on standard units (e.g., adults are advised not to regularly exceed 14 alcohol units per week in the UK), the researchers propose that a similar unit could be applied to cannabis.

The aim of this work is for people who use cannabis as well as clinicians and public health bodies to prioritise THC units – which reflect both cannabis potency and the amount consumed – rather than relying solely on frequency of use.

The findings recommend that adults should not exceed 8 THC units per week – equivalent to about 40 mg of THC or 1/3 gram of herbal cannabis.

Above these thresholds, people are at greater risk of developing cannabis use disorder (CUD), a condition that affects an estimated 22% of people who regularly use cannabis. This is a problematic pattern of cannabis use causing clinically significant impairment or distress. Symptoms can include cravings, struggling to control use, and cannabis interfering with work, family or other relationships.

In the new study, Dr Rachel Lees Thorne and Professor Tom Freeman – the lead and senior researchers from the Department of Psychology at Bath involved in this work – have applied this unit to establish, for the first time, thresholds at which cannabis could be considered ‘safer’.

Dr Rachel Lees Thorne said: “The ultimate goal of our new guidelines is to reduce harm. The only truly safe level of cannabis use is no use. However, for those who don’t want to stop or are unable to, we still want to make it easier for them to lower their risk of harm. For instance, a person might opt to use lower-THC products or reduce the quantity of cannabis they use.

“These guidelines are designed to offer realistic, evidence-based advice for those who want to make informed choices.”

When cannabis use reaches a higher risk level

The new research drew on data from the CannTeen study conducted at UCL, which tracked 150 people who used cannabis, assessed the severity of CUD and estimated their weekly THC unit intake over a year.

The team established that for adults, the risk of CUD increases above 8 THC units per week, with the risk of more severe CUD rising above 13 units per week. In the CannTeen sample, 80% of people who used below 8 THC units did not have CUD, while 70% who used above this amount reported CUD.

Professor Freeman said: “Cannabis is one of the most widely used drugs in the world.  Despite this, there is no information for consumers about how different levels of consumption might affect them.

“Safer use thresholds based on standard THC units could help people better understand their level of use and make informed choices about their health. Such thresholds could be used by public health bodies and in healthcare settings for communicating the risks of an individual’s level of consumption, and for tracking reductions in use.

“As cannabis becomes increasingly available in legal markets around the world it is more important than ever to help consumers make informed choices about their use.”

Building on these initial findings in a UK sample, the team plans to look at safer cannabis thresholds across larger international samples, and to develop tools to help people track their unit consumption in different international contexts.

Better labelling in countries where cannabis is legal

The Bath research is already attracting international interest, particularly in countries with legal cannabis markets, such as Canada, where there is growing momentum to include THC unit information on product labelling, in the same way as alcohol products are labelled with alcohol units in the UK.

The Canadian Centre on Substance Use and Addiction is leading a global working group on cannabis units, and the Bath team has shared its findings to support this work.

Dr Robert Gabrys, senior research and policy analyst at the Canadian Centre on Substance Use and Addiction (CCSA), said Canada’s expert panel for the legislative review of the Cannabis Act has made it a priority to develop a ‘standard dose’ for cannabis products.

He said: “Cannabis legalisation in Canada has brought a much wider range of products to the market. With that, many people face challenges understanding product labels and how to safely dose their cannabis products. This has led to the need for more effective approaches to help people interpret product information and better understand the potential health effects of their cannabis use.

He added that the research from Bath, “is an important part of this effort, as it demonstrates how a standard THC unit can be used to predict and communicate health risks – in this case CUD.”

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Journal

Addiction

DOI

10.1111/add.70263 

Method of Research

Observational study

Subject of Research

People

Article Title

Estimating thresholds for risk of cannabis use disorder using standard delta-9-tetrahydrocannabinol (THC) units

Article Publication Date

12-Jan-2026

 

Childhood exposure to air pollution linked to poorer cognitive performance in later life

A new study shows that childhood exposure to indoor air pollution may have long-term effects on brain health, with possible cognitive impairment appearing decades later

University of Helsinki

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People across the globe, especially in low-income countries, continue to use solid fuels like coal, wood and plant waste for cooking and heating. The resulting indoor air pollution exposes children to smoke and particles at key stages of brain development.

“Nearly 30% of the global population, roughly 2.4 billion people, still cook without clean fuels. Our findings indicate that growing up in a smoke-filled household may impair brain health and cognitive abilities throughout life,” says University of Helsinki researcher Xu Zong.

Published in Social Science & Medicine, a leading international journal on health and social medicine, the study is the first to investigate how early-childhood exposure to indoor air pollution affects cognitive performance in adulthood. It analysed nationally representative data from over 7,000 Chinese adults aged 45 and above, using advanced machine learning techniques.

Childhood exposure may accelerate cognitive decline in brain function

Individuals exposed as children to indoor air pollution from solid fuels performed significantly worse on cognitive tests in adulthood.

“The association remained strong in two key areas of cognitive function: episodic memory and overall mental health. This indicates that early exposure may accelerate age-related cognitive decline in several areas of brain function,” notes Zong.

The study further explored how childhood exposure to indoor air pollution may contribute to poorer cognitive performance in later life, identifying two main pathways: biological and socioeconomic.

Among biological mechanisms, overweight and limitations in daily activities were highlighted, suggesting that early exposure may harm long-term physical health and indirectly impact brain function.

In terms of socioeconomic mechanisms, childhood exposure to air pollution was associated with lower levels of education and income in adulthood, both of which are known risk factors for cognitive decline.

Gender differences significant, with tobacco and alcohol use also prominent

Men, smokers and regular alcohol users were particularly vulnerable to the detrimental effects of early exposure to indoor air pollution on cognitive performance. The results are consistent with the idea that inflammation and stress – often exacerbated by tobacco or alcohol use – may amplify the neurological damage caused by air pollution.

“Our study emphasises that early exposure to air pollution affects later cognitive health through both biological and social pathways,” says Zong.

“That is why public health efforts should combine clean energy initiatives with preventive strategies that support lifelong health and positive behaviours.”

Towards clean household energy

The results underscore the need for global policies promoting clean household energy, particularly in regions where reliance on solid fuels remains high.

“Switching to cleaner fuels, such as gas or electricity, is not merely an environmental or respiratory health measure. It is also an investment in long-term cognitive wellbeing that could safeguard brain health for future generations,” states Zong.

Further information:
Xu Zong
+358  294 123094
xu.zong@helsinki.fi

Publication:
Zong, X. (2025). The long arm of childhood: The association between early-life indoor air pollution exposure and cognitive performance in later life. Social Science & Medicine, 387, 118662.

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Journal

Social Science & Medicine

DOI

10.1016/j.socscimed.2025.118662 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

The long arm of childhood: The association between early-life indoor air pollution exposure and cognitive performance in later life

 

Lakes are “running a fever”: is urbanization the hidden driver?

Science China Press

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The urban heat island effect and surface thermal runoff generated by the city significantly influence the climate and exacerbate lake warming.

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Credit: ©Science China Press

Urbanization is significantly amplifying lake warming, acting as a powerful regional driver of thermal alteration in freshwater ecosystems. A comprehensive study analyzing four decades of data from 587 major lakes across China, published in Science Bulletin, provides large-scale empirical evidence of this phenomenon, revealing a clear and quantifiable dose-response relationship between urban development and accelerated lake surface water temperature (LSWT) increase.

The study’s most compelling findings demonstrate unmistakable spatial and intensity-based patterns in warming linked directly to urbanization:

(1) Southeast vs. Northwest: Using the well-known Hu Huanyong Line—which divides China into densely populated southeastern regions and sparsely populated northwestern areas—researchers found lakes in the southeast warmed 58.3% faster (0.19 ± 0.05 °C/10a) than those in the northwest (0.12 ± 0.03 °C/10a).

(2) Urban vs. Non-Urban Watersheds: Lakes located in watersheds with urban development warmed at a rate of 0.16 ± 0.05 °C/10a, 33.3% higher than lakes in watersheds without urbanization (0.12 ± 0.03 °C/10a).

(3) High vs. Low Urbanization Intensity: Among lakes in urbanized watersheds, those experiencing high urbanization intensity (UI) warmed 31.3% faster (0.21 ± 0.04 °C/10a) than those subject to lower UI (0.16 ± 0.05 °C/10a).

“These three tiers of comparison deliver a clear message: the more intense the urban development around a lake, the more it heats up,” said Yi Luo, corresponding author of the study from Yunnan Normal University.

The research also highlighted the heightened vulnerability of smaller lakes. Those with a volume below 0.1 km3 warmed 25% faster than larger lakes (>1 km3). The study identified a critical volume threshold of 2.5 km3; lakes larger than this volume exhibited markedly slower warming rates, underscoring the role of thermal mass in buffering against temperature increases.

This warming is driven primarily by the urban heat island effect, through which urbanization modifies local microclimates and hydrological processes:

(1) Heated Air: Impervious surfaces like asphalt and concrete absorb and reradiate heat, elevating local air temperatures (AT). Urbanization amplified the contribution of AT to LSWT warming by 32.0%.

(2) Thermal Runoff: Hard surfaces prevent water infiltration, resulting in heated stormwater runoff that carries excess thermal energy directly into lakes.

(3) Inhibited Cooling: The loss of vegetative cover reduces evapotranspiration (ET)—a natural cooling process. Urbanization decreased the cooling contribution of ET by 13.4%, and reduced the role of precipitation (P) by 14.9% due to altered runoff patterns.

“Urbanization doesn’t just add heat—it also undermines the lake’s innate ability to cool itself, effectively magnifying the impact of climatic warming,” noted Yi Luo.

This accelerated warming poses severe ecological threats:

(1) Stratification Disruption: Unstable thermal stratification can lead to deep-water oxygen depletion and fish kills.

(2) Algal Blooms: Increased temperatures and nutrient release from sediments elevate the frequency and severity of harmful algal blooms.

(3) Biodiversity Loss: Warmer waters shrink habitats for cold-water species, prompting migration and loss of aquatic diversity.

These impacts endanger critical ecosystem services provided by lakes, including drinking water supply, fisheries, recreation, and climate regulation.

The study establishes urbanization as an independent and significant factor exacerbating lake warming on a regional scale. “Future projections of lake ecosystem changes must incorporate local anthropogenic influences,” the authors urge. The findings provide a scientific foundation for sustainable urban planning, suggesting that expanding blue-green infrastructure—such as vegetative buffers around lakes—could help mitigate warming and preserve freshwater resources.

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Journal

Science Bulletin

DOI

10.1016/j.scib.2025.11.028 

Method of Research

Data/statistical analysis