Improved tolerance to bile salts of aggregated Bifidobacterium longum produced during continuous culture with immobilized cells.
The effect of cell immobilization and continuous culture was studied on selected physiological and technological characteristics of Bifidobacterium longum NCC2705 cultivated for 20 days in a two stage continuous fermentation system. Continuous immobilized cell (IC) cultures with and without glucose limitation exhibited formation of macroscopic cell aggregates after 12 and 9 days, respectively. Auto-aggregation resulted in underestimation of viable cell counts by plate counts by more than 2 log units CFU/ml compared with qPCR method. Modifications of cell membrane composition might partially explain aggregate formation in IC cultures. Decreases in the ratio of unsaturated to saturated fatty acid content from 1.74 to 0.58 might also contribute to the enhanced tolerance of IC cells to porcine bile salts and aminoglycosidic antibiotics compared with free cells from batch cultures. The enhanced resistance against bile salts in combination with auto-aggregation may confer an advantage to probiotic bacteria produced by IC technology.
Laboratory of Food Biotechnology, Institute of Food Science and Nutrition, Schmelzbergstrasse 7, ETH-Zurich, 8092 Zürich, Switzerland.
Sebastian
S
Reimann
Franck
F
Grattepanche
Rafael
R
Benz
Valeria
V
Mozzetti
Enea
E
Rezzonico
Bernard
B
Berger
Christophe
C
Lacroix
D000222:Adaptation, Physiological / Q000187:drug effects*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001644:Bifidobacterium / Q000166:cytology* / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D001647:Bile Acids and Salts / Q000494:pharmacology*; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D018929:Cell Culture Techniques / Q000379:methods*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D018914:Cells, Immobilized / Q000166:cytology / Q000187:drug effects; D005227:Fatty Acids / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006358:Hot Temperature; D050296:Microbial Viability / Q000187:drug effects; D034421:Sus scrofa
D000900:Anti-Bacterial Agents; D001647:Bile Acids and Salts; D005227:Fatty Acids