Reference : Study of viability of Pseudomonas fluorescens BTP1 freeze-dried during storage at 4 a...
Scientific congresses and symposiums : Poster
Life sciences : Agriculture & agronomy
Study of viability of Pseudomonas fluorescens BTP1 freeze-dried during storage at 4 and 20°C
Mputu Kanyinda, Jean-Noël [Université de Liège - ULiège > > > Doct. sc. agro. & ingé. biol.]
Thonart, Philippe mailto [> >]
European Plant Genetic Resources Conference 2011
from 5-4-2011 to 7-4-2011
European Association for Research on Plant Breeding Section Genetic Resources
[en] Viability ; Freeze-drying ; Flow cytometric ; Cellular fatty acids ; cryoprotectants
[en] The drying of bacteria remains a major alternative in order to keep them long term. After centrifugation, the bacterial pellet of Pseudomonas fluorescens BTP1 was divided in two fractions one with and one without cryoprotectants (2% glycerol and 5% maltodextrine) and freeze-dried. After freeze drying, powders were sealed in aluminium bag under vacuum and storage at 4 or 20°C. The storage stability of freeze-dried powders was studied by parameters such as loss of viability on the Plate Count Agar (PCA) (e.g. Concentration of Cells with glycerol (PG) at CFU/g before storage 109 and after 7 month, 108 at 4°C and 107 at 20°C) and evolution in membrane composition by measuring the ratio of unsaturated/saturated fatty acid. These ratios decrease in function of time (e.g. at 4°C the ratios of C18:3 and C18:2 by C16:0 decreases respectively of 0,013 to 0,001 and 0,05 to 0,03 after 60 days of storage). Viability (%) and concentration (CFU/g) of bacterial during storage at 4 or 20°C with aw = 0,32 was determined using a procedure published by (Kurtmann et al., 2009). In the present study, flow cytometric analysis was applied to evaluate the state in which are the cells at the end of storage time. Furthermore, we compared result the survival of bacteria as obtained by plate count with the flow cytometric analysis results.
Centre Wallon de Biologie Industrielle
Conseil Alimentaire (CONSALIM)

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