In this thesis, bioorthogonal chemistry is combined with correlative light-electron microscopy to selectively label and study pathogenic intracellular bacteria within the host immune cell.

How do mycobacteria subvert the defenses of host immune cells?

What are the host immune defence mechanisms that control intracellular infections and how are these subverted by pathogens?

Antimicrobial resistance is one of the biggest threats to human health worldwide in the coming decennia.

Beneficial plant-associated microbiota, particularly those inhabiting the rhizosphere, contribute substantially to plant health through pathogen suppression, stimulation of plant defence responses, and enhanced nutrient acquisition.

Promotores: A.H. Meijer, H.P. Spaink

Extending our current arsenal of antibiotics is key to staying ahead in the arms race between humans and resistant bacteria.

This thesis investigates innovative and classical strategies in glycoconjugate vaccine development to address the growing threat of multidrug-resistant bacterial infections.

Parasitic worms and stomach bacteria suppress immune reactions such as allergic responses. Parasitologist Hermelijn Smits and lung specialist Christian Taube from the LUMC are trying to learn from these micro-organisms.

Understanding how nature captures and transfers solar energy is essential both for elucidating biological photosynthesis and for guiding the design of artificial light-harvesting systems.

How do lipases in Mycobacterium tuberculosis help the bacteria survive, and can we target them to create new antibiotics?

Plant-microbe interaction resulted in different physio/chemical responses by host plant and interacting rhizobacteria.

Bacteria use antibiotics as a weapon and even produce more antibiotics if there are competing strains nearby. This is a fundamental insight that can help find new antibiotics. Leiden scientists Daniel Rozen and Gilles van Wezel published their research results in the authoritative Proceedings of the…

Polymyxins are clinically used antibiotics, discovered in mid-20th century. Once abandoned due to excessive nephrotoxicity, they are now used increasingly to address infections caused by multi-drug resistant Gram-negative bacteria.In this thesis, we describe the development and synthesis of analogues…

Global healthcare is on the verge of an antibiotic availability crisis as bacteria have evolved resistance to nearly all known antibacterials. Identifying new antibiotics that operate via novel modes-of-action is therefore of high priority.

Exploiting the Ecological Role of Natural Products as Novel Biocontrol Agents (LIPQUORUM): The central aim of LIPQUORUM is to unravel the intricate interkingdom signaling mechanisms between the Bacillus subtilis species complex and the devastating fungal pathogen Sporisorium scitamineum.

In an unpredictable environment bacteria evolve the same strategy as shareholders who try to protect themselves against unpredictable swings in the stock market. Experimental evolution biologist Dr Bertus Beaumont published an article on this discovery on 5 November in the journal Nature.

Soil bacteria can produce a wealth of antibiotics that are new to us, claims Gilles van Wezel, Professor of Molecular Biotechnology at the Institute of Biology Leiden. His research group has developed a method that can rapidly identify and produce these unknown compounds.

How do bacteria sense and adapt to their environment? Ariane Briegel, Professor of Ultrastructural Biology, is intrigued by this question. Using new techniques, she produces three-dimensional images of bacteria that provide us with new clues about their sensory system.

Thread-like bacteria make cells that no longer have a cell wall under the influence of osmotic stress. A remarkable discovery, since the cell wall serves as a protection barrier for bacteria. It could also help to explain how pathogenic bacteria can hide in our body from our immune system. A team of…

Vancomycin is a last-resort antibiotic for the treatment of many Gram-positive bacterial infections, while remaining inactive against Gram-negative strains.

Inaugural lecture

Bacteria whirl around in the mouths of most people, forming dental plaques and sometimes causing nasty gum infections. Treponema denticola might be a dangerous pathogen, but not much is known about this bacterium. It was up to Ariane Briegel and her research group to change that.

Imagine that you need to travel, but you don’t have a car and you’re dead broke. What do you do? Hitchhiking, of course! Leiden biologists found that certain bacteria use this very same tactic: their spores hop on motile bacteria and use them as a taxi, ensuring they reach the right environment to f…

Last Friday the global Antibiotics Awareness Week begun: an entire week dedicated to antibiotic use. Antibiotics researchers from the LACDR therefore set out to tell primary school pupils about their research. Through role-playing, pupils were drawn into the world of antibiotics: 'Can the teacher not…

Freezing bacteria super fast to gain a true-to-nature image of the internal and external structure. Ariane Briegel Professor of Ultrastructural Biology came to Leiden specially to carry out this research. Leiden University is one of the few institutes in the world to have the necessary equipment. Inaugural…

For the first time, it was shown in living cells how the bacterium E. coli regulates genes that help it survive in a new environment. Biochemist Fatema Zahra Rashid managed to do this using a technique she fine-tuned. Her research into changes in 3-dimensional chromosome structure offers clues for ways…

This thesis examines strategies to address the global threat of antimicrobial resistance (AMR). Antimicrobial resistance poses an increasing global health risk, highlighting the need for new treatments against Gram-negative pathogens.

The challenge is considerable, but so is the satisfaction when it succeeds: creating complex sugar molecules that play a role in biology.

Ariane Briegel wants to use bacteria to detect cancer at an early stage. Together with postdoc Alise Muok, she is developing a method to quickly and cheaply test the urine of patients for the presence of suspicious molecules. They receive a grant of approximately 150,000 euros from the Dutch Cancer…

The enormous adaptability of the cholera bacterium explains why it is able to claim so many victims. Professor Ariane Briegel from the Leiden Institute of Biology has now discovered that this adaptability is due to rapid sensory changes in the bacterium. Publication in PNAS.

When a bacterium becomes more resistant to one antibiotic, it sometimes becomes more sensitive to another. To better understand this interaction, researchers from the Leiden Institute of Biology (IBL) and the Leiden Academic Center for Drug Research (LACDR) under supervision of Daniel Rozen and Coen…

A patent for what may be a potent, new antibiotic. And: a clear overview of promising approaches to overcome a crucial resistance tactic employed by bacteria. In the span of one week, two researchers from Leiden are receiving their PhDs, each of them on an important step in the battle against bacteria…

The bacterium Vibrio cholerae is a serious threat to our health because it is the causative agent of cholera. Worldwide, over a billion people per year are at risk of cholera infection. New strains of V. cholerae are resistant to the multiple drugs used to treat cholera, meaning that new types of drugs…

The central question of this Vici proposal is to investigate if, and how actinobacteria exploit life without a cell wall.

Researchers from the Institute of Biology Leiden have discovered how good intestinal bacteria regulate our innate immune system. This surprising discovery could make it possible to treat diseases related to inflammation, such as diabetes and colitis, with a cocktail of good bacteria. Publication in…

With the rise of multi-drug resistant bacterial pathogens, the possibility of a post-antibiotic world is quickly becoming reality.

Leiden PhD candidate Jo-Anne Verschoor discovered that nearly twenty percent of the bacterial strains she studied could degrade plastic, though they needed some encouragement to do so. ‘Bacteria are just like people,’ says Verschoor. Her research was published in the journal Communications Biology,…

Bacteria temporarily live without their cell wall if dangerous viruses are near. A remarkable feature, as the cell wall is a sturdy barrier against threats. Still, the discovery has a logical explanation ánd might be of a consequence for fighting pathogenic bacteria, according to Véronique Ongenae,…

Plants rely on multilayered immune systems to detect and restrict pathogen invasion while minimizing damage to host tissues. This thesis investigates the regulation, spatial organization, and functional consequences of effector-triggered immunity (ETI) in Arabidopsis thaliana.

Macrophages – the front line of our immune system – protect us from infections. But in the case of the tuberculosis bacteria, this often goes wrong. The group of Annemarie Meijer from the Leiden Institute of Biology has now discovered that macrophages in zebrafish are better able to eliminate tuberculosis…

Antimicrobial drugs constitute a fundamental part of modern medicine. The global rise in antimicrobial resistance poses a major threat to global health.

Jo-Anne Verschoor wins the Unilever Research Prize 2020. The master's student in Biology developed a method to test whether bacteria are capable of degrading plastic. Verschoor: 'Using specific enzymes from these bacteria, we may be able to efficiently recycle plastic in the future.

Biological chemist Nathaniel Martin is going to test an alternative antibiotic that can combat common resistant bacteria such as MRSA. For this purpose, he will receive 350,000 euros from the NWO's NACTAR programme. ‘We want to know how safe and effective our antibiotic is in a realistic situation.’

We investigate bacteria and fungi to understand their malicious or beneficial impact on food crops and their pathogenic or antibiotic role in human health.

Streptomyces are prolific producers of enzymes and secondary metabolites, including more than 50% of all clinical antibiotics. This makes them highly attractive for medical, biotechnological, and industrial purposes.