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Yeast-based Nutrients Selection: a Key Choice to Improve Your Probiotics Production

Lactic Acid Bacteria (LAB) and other probiotic bacteria have complex nutritional needs to consider carefully to reach your high cell count objectives. Among those, yeast-based nutrients are key components of the culture media since they are an excellent source of biological nitrogen. Procelys latest studies highlighted that yeast-based nutrients also play an important role when evaluating the potency of your strain in a specific application.

High quality probiotics

Probiotics are defined by the World Health Organization as “Live microorganisms which when administered in adequate amounts confer a health benefit on the host”. The main microorganisms used as probiotic products for human consumption belongs to the Lactobacillus and Bifidobacterium genera, usually referred as lactic acid bacteria (LAB).

LAB are widely used by the food industry for their proven functional properties and their beneficial effect on health. There are numerous supportive evidences that probiotics can help treating or reduce diseases. To achieve such a target, probiotics need to comply with some conditions e.g., to be administered on a regular basis, in adequate quantity and to reach their site of action alive and active.

Why are these three conditions necessary? The first reason is that probiotics seem to be unable to colonize durably the host gastric digestive tract. It is estimated that the daily intake for probiotics is about 106 to 107 CFU/g of product depending on the country. Indeed, an enough number of cells must survive the harsh conditions of the digestive tract and arrive alive to their site of action for probiotics to have a beneficial effect on health.

Thus, to ensure high quality probiotic products it is equally important to produce high cell counts as well as to evaluate probiotics cells ability to survive the digestive tract.

Maintain the viability of the cultured cells throughout the digestive tract.

Several parameters affect cells viability and vitality during their fermentation such as temperature, aeration, fermentation time or the composition of the culture medium. Probiotic strains have complex nutritional requirements that yeast-based nutrients can cover as nitrogen sources.

Yeast-based nutrients are biological biochemically complex nitrogen sources rich in amino acids, peptides, carbohydrates, vitamins and minerals helping cells to achieve superior and robust growth.

During a preliminary bioprocess optimization for probiotics manufacture, it is important to carefully select the optimal yeast-based nutrient depending on the strain to increase the cell counts, given each strain has its own needs.


Moreover, Procelys also demonstrated that yeast-based nutrient can also affect the ability of LAB cells to survive harsh conditions in the stomach and particularly exposition to gastric juice.

To come to that conclusion, a LAB model strain fermentation followed by a simulated gastric juice (GJ) trial was performed. This test aimed to mimic in a simple way how LAB tolerate the acidic conditions of the stomach.

The methodology consists in inoculating, after fermentation, LAB in a simulated gastric juice medium. The CFU difference before and after the study is then measured.

The results indicated that depending on the media yeast-based nutrients content used for the upstream fermentation; the yeast-based nutrients yielding the highest cell counts during the culture were not necessarily the condition from which the highest cell counts were measured after being subjected to the simulated GJ.

For instance, in the case of B.lactis the log CFU decrease after the GJ test was about 60% after being cultivated with NuCel® 783 whereas it was about 34% when cultivated with NuCel® 532, which represent a 30% viability difference just by switching the yeast extract. Moreover, the cell counts before the GJ test was higher with NuCel® 783 than with NuCel® 532, which is the contrary after being subjected to the GJ test.

Thus, we were able to demonstrate the importance of selecting the optimal yeast-based nutrient not only based on the resulting cells viability at the end of a fermentation, but also owing to yeast-based nutrients ability to maintain the viability of the cultured cells throughout the digestive tract.

Considering yeast-based nutrients as biological nitrogen source for your lactic acid bacteria production?

Watch our latest webinar about Probiotics Challenges or contact our team to get a presentation of YEAST-BASED NUTRIENTS SELECTION IS A KEY PARAMETER INFLUENCING PROBIOTIC STRAINS CELL RESISTANCE TO GASTRIC JUICE white paper.