These results were an indication of the growth phase dependency of the culture for during stress. Conclusion In this study, we were able to show that the system to simulate the stomach-intestine passage developed by Sumeri et al.  was suitable for the assessment of survival of 8 Bifidobacterium
strains and Lactobacillus gasseri K7 even though we did not simulate the removal of gastric juice and selleck chemical bile salts. For L. gasseri K7 we were able to compare the results with an in-vivo study on piglets and obtained similar results. The single reactor system presented here allows a more straightforward identification of the ideal growth phase for any possible probiotic strain which is required to pass the stomach-intestine passage than if it had to be performed with other systems Alpelisib order with a difficult setup. The study also showed that all tested Bifidobacterium strains, except for B. animalis subsp. lactis, would require protective agents to survive the passage through the stomach-intestine in high numbers. This could be done using an appropriate food matrix or encapsulation of the cells. Methods Bacterial strains All bifidobacteria strains were selected from the strain collection of Agroscope Liebefeld-Posieux ALP Research Station Switzerland, isolated by ALP from human sources. Lactobacillus gasseri K7 originated from the ZIM Collection of Industrial Microorganisms of University of Ljubljana, Biotechnical
Faculty (ZIM 105)  and was also deposited in the ALP strain collection. The tested strains and their identification numbers of the ALP strain collection are listed in table 3. All bifidobacteria Glycogen branching enzyme strains are the property of ALP. Media and growth conditions For pre-cultures, 1 ml frozen conserves of the strains were inoculated in 250 ml Wilkins-Chalgren broth (WC CM0643, Oxoid, Hampshire, UK) supplemented with 9 g l-1 additional lactose-monohydrate (Bifidobacteria) or De Man-Rogosa-Sharpe (MRS; Biolife, Milano, Italy) medium (Lactobacillus gasseri K7) . For L. gasseri K7, a trial with a 100 ml pre-culture was also performed.
All strains, except Bifidobacterium longum subsp. infantis, were incubated at 37°C for 15 hours under anaerobic conditions. Bifidobacterium longum subsp. infantis was incubated for 12 h since it was very sensitive to BIIB057 ic50 extended incubation periods. The pre-cultures were centrifuged for 15 min at 3500 rpm and the pellets resuspended in 10 ml of phosphate-buffered physiological sodium chloride solution (PBS). Determination of cell count The cell count was determined by 10-fold serial dilution of the culture in physiological saline solution. The two highest dilutions were then plated on MRS agar (Biolife, Milano, Italy) using a spiral plater (IUL Instruments, Barçelona, Spain) and evaluated by an automated colony counter with the corresponding software (IUL Instruments, Barçelona, Spain).