Probiotic processing conditions & their impact on biological activities


Probiotics are defined as “live microorganisms which when administered in an adequate amount confer a health benefit to the host”. With the rapid development of DNA sequencing technologies, this research has entered a new era and identification of bacterial effector molecules is progressively increasing. Efficient technologies have also been developed to produce highly concentrated and stable probiotics. However, the impact of production processes on the probiotic biological activities, and/or the expression and function of the effector molecules, remains poorly studied. At present product quality control commonly employs Colony Forming Units (CFUs) as its main criterion to evaluate successive batches of probiotic biomass/powders. Moreover, it is also unknown if the behaviour and health-benefit efficacy of probiotics in the gut ecosystem is affected by prior processing steps. Thereby, the two questions below remain largely unanswered to date:

1.       What is the impact of production process conditions on the biological activities, effector molecule expression and function of a probiotic?

2.       Is the behaviour of a probiotic in the gut ecosystem affected by prior processing steps?


The overall objective of this project are to evaluate and prioritize the role of different processing parameters on probiotic biological activity, using selected model strains with (at least partially) known effector molecules. It aims at developing a workflow that could be applied to probiotic strains and would facilitate optimization of probiotic production based on effector molecule expression and efficacy rather than on viable cells only.


Bacterial culturing (including bioreactor technology) & small scale processing, RNA & protein isolation, transcriptomics, proteomics, enzymatic assays.


Students pursuing a degree in Molecular Life Sciences, Biotechnology, Microbiology or related discipline. Background in either molecular biology or biochemistry (previous experience with microbiological culturing is preferred).

This project will be pursued at the Nestlé Research in Lausanne, Switzerland. Interested in an abroad experience within an international food company ? Contact us !

Contact information

Prof. dr. Michiel Kleerebezem,; Stéphane Duboux,