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Molecular Biology and Microbial Food Safety

Research lines Molecular Biology and Microbial Food Safety

Outline of the different research themes MBMFS

In this Powerpoint presentation the different themes of the research group Molecular Biology and Microbial Food Safety are outlined.


View powerpoint of research at Molecular Biology and Microbial Food Safety

Food spoilage & pathogenic bacteria

(i) Bacterial spore formers

The behaviour of aerobic spore formers is studied in the model  Bacillus subtilis. Spore forming organisms are spoilage organisms of prime-importance to the food industry due to their highly stress resistant endospores. Their occurrence necessitates the application of harsh food preservation processes such as high thermal treatments. The mechanistic basis of their extreme high thermal resistance (some for various minutes at 121˚C) as well as the molecular mechanisms involved in the early phases of spore germination and outgrowth under optimal and sub-optimal environmental conditions, are still far from mechanistically understood. We focus on analysis of thermally stressed spores growing out under weak-organic acid preservative stress. The data provide new targets for the enhancement of the efficacy of weak-organic acids as food preservative. For proteomic analyses of the spore coat we collaborate extensively with the department of 'Mass Spectrometry of Bio-macromolecules' at SILS. The analyses are extended to include (validation in) Bacillus cereus and Clostridium difficile.

B subtilis spore
Bacterial spore former

(ii) Antibiotic resistance development in the food chain

Bacteria of relevance to microbial food safety are prone to acquire resistance towards environmental conditions such as the use of antibiotics in animal feed practices. Such events create potentially harmful situations to the medical field as multiple antibiotic resistance development may occur and could well harm the effective use of these antibacterial agents in treating infection. Our group focuses on the development of systems to study (1) acquisition of antibiotic resistance, (2) transmission of antibiotic resistance, (3) loss of antibiotic resistance. For all scientific questions we make use of well accessible model systems (primarily Escherichia coli) and controlled culture conditions (fermentors and chemostats). This research is led by Dr. Benno Ter Kuile of the Dutch Food Safety Authority (NVWA) who holds a part-time research position at our department.

Funded by NWO, EU Erasmus Mundus, Chinese Scholarship Councli & NVWA

Antibiotic resistance
Antibiotic resistance development in the food chain
prof. dr. S. (Stanley) Brul

Faculty of Science

Swammerdam Institute for Life Sciences

prof. dr. B.H. (Benno) ter Kuile

Faculty of Science

Swammerdam Institute for Life Sciences

View powerpoint on antibiotic resistance development

Studies on antimicrobial peptides with Medical Microbiology (AMC)

Membrane Domains are Formed with Thrombocidin-derived TC peptides and BP2

Medical Microbiology is the field of research in which molecular and physiological tools are used to unravel the behaviour of disease causing microorganisms. We focus on the response of the organisms to antimicrobial peptides of natural origin (i.e. Thrombocidin derived). The studies have both a fundamental and an applied angle. At MBMFS our focus is primarily on the fundamental aspects of the behaviour under antimicrobial peptide stress using Bacillus subtilis as a model. Validation is done in Bacillus cereus and Clostridium difficile. We identified that antimicrobial peptides act upon the membrane of cells and lead to a perturbation of membrane fluidity homeostasis. In collaboration with and funded by TNO, data were also gathered on alternative non proteinaceous compounds. Together with the department for Medical Microbiology at the Academic Medical Centre (AMC) we provide studies to understand the molecular basis of damage and response to novel antimicrobial compounds with potential for medical application.

Funded by :  EU Erasmus Mundus Action 2 program (EMA 2)

Laurdan GP
Laurdan GP microscopy
prof. dr. S. (Stanley) Brul

Faculty of Science

Swammerdam Institute for Life Sciences

Fungi and response to environmental stress

The interaction of bakers yeast (Saccharomyces cerevisiae) with weak organic acids, prominent in the food industry is studied. Together with the group of prof. Teun Boekhout at IBED we aim at capitalising on our gathered understanding of pathogenic yeast behaviour (Candida albicans). Prime focal points are thermal and weak-organic acid stress response as well as a basic understanding of effects of intracellular pH on growth. We deploy our knowledge for the understanding of the behaviour of Aspergilli in the production of organic acids. A project focusing on itaconic acid is sponsored by Dutch DNA Biotech and TNO. In our experimental set-up we focus on analysing and subsequently providing targets for interfering with stress (cross-)tolerance mechanisms. For proteomic analyses of the response to environmental stress we collaborate extensively with the department of Mass Spectrometry of Biomolecules at SILS.

Funded by University funds, TNO, Dutch DNA Biotech.

dr. G.J. (Gertien) Smits

Faculty of Science

Swammerdam Institute for Life Sciences

prof. dr. S. (Stanley) Brul

Faculty of Science

Swammerdam Institute for Life Sciences

Fermentation for biobased production of (high-value) chemicals

As crucial part of the developing Biobased Economy, the chemical industry is looking for alternative, sustainable, production processes for all/most of their bulk and fine chemicals, fuels, pharmaceuticals and food ingredients. Since most of these processes are not yet available and/or not yet affordable, this offers major possibilities for research groups in this area. Within the MBMFS-group, prof Jeroen Hugenholtz employs the process of microbial fermentation as THE technology for biobased production of many chemicals. The work, currently, focuses on three areas of fermentation; 1. Anaerobic fermentation, involving Clostridium, for production of various alcohols from (biological) waste streams and C1-gasses (syngas); 2. Lipid-producing and lipid-converting microorganisms such as Cryptococcus and Pseudomonas that can produce and convert various medium- and long-chain fatty acids; and 3. Lactic acid bacteria as starter culture and as ingredient producer for preservation, flavour development and nutritional enrichment of food products. In general, the research focuses on cost-effective production of the chemicals/ingredients by using (cheap) waste streams from e.g. the AgriFood industry as substrates for fermentation and by using various microbial physiology/fermentation/metabolic modelling approaches to achieve maximal production of the desired microbial components.

The described work is an important part of the Amsterdam Green Campus-initiative and is fully connected with various Biorefinery and Biobased Production activities running at Wageningen Research, through the employment of prof Hugenholtz at this organisation.

Vegetable fermentation for increased shelf-life
EXAMPLE 1. Vegetable fermentation for increased shelf-life
Oil-accumulating yeast for biobased fatty acid production
EXAMPLE 2. Oil-accumulating yeast for bio-based fatty acid production
prof. dr. J. (Jeroen) Hugenholtz

Professor by special appointment