Alex Ter Beek

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The specific pH values of cellular compartments affect virtually all biochemical processes, including enzyme activity, protein folding and redox state. Accurate, sensitive and compartment-specific measurements of intracellular pH (pHi) dynamics in living cells are therefore crucial to the understanding of stress response and adaptation. We used the(More)
Bacillus subtilis forms dormant spores upon nutrient depletion. Under favorable environmental conditions, the spore breaks its dormancy and resumes growth in a process called spore germination and outgrowth. To elucidate the physiological processes that occur during the transition of the dormant spore to an actively growing vegetative cell, we studied this(More)
The respiratory chain of Escherichia coli is usually considered a device to conserve energy via the generation of a proton motive force, which subsequently may drive ATP synthesis by the ATP synthetase. It is known that in this system a fixed amount of ATP per oxygen molecule reduced (P/O ratio) is not synthesized due to alternative NADH dehydrogenases and(More)
Oxygen availability is the major determinant of the metabolic modes adopted by Escherichia coli. Although much is known about E. coli gene expression and metabolism under fully aerobic and anaerobic conditions, the intermediate oxygen tensions that are encountered in natural niches are understudied. Here, for the first time, the transcript profiles of E.(More)
Spore-forming bacteria are a special problem for the food industry as some of them are able to survive preservation processes. Bacillus spp. spores can remain in a dormant, stress resistant state for a long period of time. Vegetative cells are formed by germination of spores followed by a more extended outgrowth phase. Spore germination and outgrowth(More)
Bacterial spore formers are prime organisms of concern in the food industry. Spores from the genus Bacillus are extremely stress resistant, most notably exemplified by high thermotolerance. This sometimes allows surviving spores to germinate and grow out to vegetative cells causing food spoilage and possible intoxication. Similar issues though more pending(More)
Bacillus species are a spoilage and safety challenge to the food industry due to their extremely resistant endospores. To interfere with (out)growth of spores and vegetative cells, weak organic acids are suitable preservatives. To ensure their continued use while optimally preserving product quality, knowledge of resistance development is important. In(More)
Bacterial spores are the ultimate (stress) 'survival capsules'. They allow strains from the Bacillus and Clostridium species to survive harsh environmental conditions. In addition to the decision to enter sporulation the decision to do the reverse (germinate) is also a decisive event after which there is no return. Generally it is observed that the(More)
The weak organic acid sorbic acid is a commonly used food preservative, as it inhibits the growth of bacteria, yeasts, and molds. We have used genome-wide transcriptional profiling of Bacillus subtilis cells during mild sorbic acid stress to reveal the growth-inhibitory activity of this preservative and to identify potential resistance mechanisms. Our(More)
The 'Omics' revolution has brought a wealth of new mechanistic insights in many fields of biology. It offers options to base predictions of microbial behaviour on mechanistic insight. As the cellular mechanisms involved often turn out to be highly intertwined it is crucial that model development aims at identifying the level of complexity that is relevant(More)
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