NIZO - Predicting and improving survival of probiotics in the gut
We have received the following news item from NIZO:

Improving survival of probiotics can now be achieved based on the identification of fermentation conditions and genes that are involved in human gastrointestinal tract persistence. This is one of the results of the work carried out by Hermien van Bokhorst-van de Veen for her PhD thesis at NIZO food research and Wageningen University within the Nutrition and Health Research Programme of TI Food and Nutrition. In view of the wide use of these bacteria in the food industry, the findings will help industry to select and develop probiotics and starter cultures with improved robustness end effectiveness.

Lactobacillus plantarum is one of the most versatile lactic acid bacteria, which can successfully inhabit a variety of niches. It is used as starter culture in food fermentations and marketed as a probiotic. Since the effectiveness of lactic acid bacteria depends on their robustness when encountering stress, it is important to understand and improve the molecular adaptations that sustain their function and viability under the challenges they encounter during processing and in the human digestive tract.

Molecular analyses and use of NIZO’s digestive tract model (Simphyd) gave insight into the fermentation conditions and genes important for stress reactions of L. plantarum. Three genes have been identified by Van Bokhorst-van de Veen that can predict survival under stress conditions such as low pH in the stomach and bile salts in the small intestine. It appears that small variations in growth conditions of L. plantarum have a large effect on survival and the expression levels of these genes. Industry can employ this type of knowledge to improve their strains’ performance under new fermentation conditions and predict their robustness and survival.

In addition, Van Bokhorst-van de Veen developed a new and fast method to determine persistence of lactic acid bacteria in healthy human volunteers by administering mixed cultures. She showed with this method that each L. plantarum strain had the same survival characteristics in each volunteer that took part in the study. In addition, the persistence characteristics could be correlated with the survival in the in vitro Simphyd model. “The relevance is obvious,” says Van Bokhorst-van de Veen. “Since the persistence measured in the human volunteers could be correlated with the survival found in the in vitro model, we can use this fast and inexpensive model to predict actual gastrointestinal tract survival. In addition, combining strains reduces the amount of work and time needed for industry to test promising strains for food applications.”

The work described in this thesis was performed under the supervision of Prof. Dr. Michiel Kleerebezem (promoter) of Wageningen University and Dr. Peter Bron (co-promoter) of NIZO food research. Hermien van Bokhorst-van de Veen will defend her thesis on July 3rd.
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