10 February 2026
Introduction
In this edition highlighting researchers who use UNLOCK’s facilities, we spoke with Natalia Nadal Alemany, whose work focuses on understanding the metabolic behavior of the fermentative microorganism Clostridium pasteurianum. The research investigates how this microbe adapts its catabolic pathways under iron-limited conditions, with particular attention to the relationship between anabolism and energy metabolism. By examining shifts in electron flow and metabolic strategies, the study aims to deepen insight into microbial flexibility and support the development of more efficient anaerobic fermentation processes. The experiments were carried out using the UNLOCK Parallel Cultivation Platform.
Could you briefly describe the focus of your thesis research?
My research focuses on the catabolism of the fermenting microbe Clostridium pasteurianum. Microbes that perform anaerobic fermentation obtain little energy per substrate, as they do not use any external electron acceptor. They usually obtain energy by a combination of catabolic pathways that allows maximal ATP yield per substrate, while closing the electron balance over the whole metabolism. Fermenting microbes possess other catabolic pathways that are less often active. The function of these pathways, the overall metabolic flexibility, and the selection of the active catabolic pathways in C. pasteurianum are the subject of my research.
Developing our understanding of fermentation is highly valuable to both fundamental and applied research. By better understanding fermentation, the similarities and differences between energy metabolisms can be drawn, shedding light on how evolution shaped them and how microbial communities work. Better understanding fermentation would allow designing more robust and efficient industrial processes that rely on anaerobic fermentation, and extend its potential for novel applications.
What were the key goals or research questions you aimed to explore?
C. pasteurianum uses iron in its preferred energy catabolism, to close the electron balance of the whole metabolism and in key steps of anabolism. The key goals of the experiment were to find the metabolic changes of C. pasteurianum under iron limitation, to better understand its flexibility and the coupling between anabolism and catabolism.
What methods or technologies did you use as part of your project?
The seed train was performed aseptically, all manipulations being done under a laminar-flow cabinet. The experiments were conducted in four bioreactor setups that were operated under anaerobic and aseptic conditions to maintain the culture pure.
The bioreactor setups were connected to a mass spectrometer that analyzed the off-gas over time. The acids and alcohols were quantified by HPLC, and the biomass by optical density and VSS/TSS quantification. The proteomics was analyzed by LC-MS/MS. Purity in the culture was ensured by aseptic practices over the whole experiment, and assessed by regular observations under the microscope and 16S sequencing.
What were the most significant results or key findings of your study?
The key finding of the study was that two new pathways became active, which changed the electron flow, while the ATP yield per substrate was only moderately impacted. This newly uncovered energy strategy proved the flexibility of the metabolism of C. pasteurianum, and revealed how the coupling with anabolism strongly shapes catabolism.
Which UNLOCK platforms or tools did you use during your research?
I used the Parallel Cultivation Platform for my research.
How did UNLOCK facilities support or enhance your work?
The UNLOCK facilities supported my work by providing a high number of available, ready-to-use, high-quality bioreactor setups, off-gas real-time analysis, and support from the UNLOCK team.
Were there any specific technical challenges or discoveries you encountered while using the platform?
There were no technical challenges while using the platform.
What did you find most valuable about working with UNLOCK?
I found most valuable the amount of available equipment, its reliability, and the space and cleanliness of the setups. These contributed to successfully conducting the experiment on the first go.
Has your experience with the platform influenced your current or future research direction?
My experience with the platform has substantially contributed to my research, and inspired new possibilities of parallel cultivations for future experiments.
Do you have any advice or tips for future students or researchers planning to work with UNLOCK?
My advice would be to explore all possibilities UNLOCK has to offer, which might add value to the research. I also recommend embracing teamwork with the UNLOCK team to ensure a successful and fruitful experiment.
