[en] The objective of this thesis is to study the resistance to drying of Pseudomonas fluorescens. Freeze-drying is the most suitable method for drying P. fluorescens. However, freeze-drying induced loss of cell viability. This loss of viability is mainly due to membrane rupture, temperature and oxidation of fatty acids, membrane proteins and glutathione. For this purpose, the use of protective compounds during freeze-drying has allowed us to obtain a powder having a high viability. We then studied the impact of these protective compounds, oxygen and storage temperature on the viability of P. fluorescens during storage. Analyses of fatty acids, proteins, glutathione and the study of membrane integrity during the various manufacturing processes and storage have established a link between the degree of oxidation and cell death. The results of flow cytometry showed that the freeze-drying longer affects the viability of P. fluorescens rather than storage. We have increased the yield of the production in bioreactor of P. fluorescens and time of culture was halved.
