Date Published: May 10, 2019
Publisher: Public Library of Science
Author(s): Anneloes E. Groenenboom, Megan E. Parker, Anne de Vries, Suzette de Groot, Stephanie Zobrist, Kimberly Mansen, Peiman Milani, Remco Kort, Eddy J. Smid, Sijmen E. Schoustra, Marie-Joelle Virolle.
Spontaneously fermented food products contain a complex, natural microbial community with potential probiotic activity. The addition of a health-promoting, probiotic bacterium to these products ensures the delivery of that probiotic activity to consumers. Here, we assess the microbial community of a traditional Senegalese milk product produced by spontaneous fermentation, called lait caillé. We produced the lait caillé in a traditional way and added a probiotic starter containing Lactobacillus rhamnosus yoba 2012 to the traditional process. We found various species that are known for their ability to ferment milk, including species from the genera Lactobacillus, Acetobacter, Lactococcus, and Streptococcus. Our results show that the addition of L. rhamnosus to the inoculum, can result in detectable levels of this strain in the final product, ranging between 0.2 and 1 percent of the total bacterial population. Subsequent rounds of fermentation using passive back-slopping without the addition of new L. rhamnosus led to a loss of this strain from the community of fermenting bacteria. Our results suggest that the addition of probiotic strains at every fermentation cycle can enrich the existing complex communities of traditionally fermented lait caillé while traditional bacterial strains remain dominant in the bacterial communities.
Fermented foods are consumed worldwide and are of increasing interest to the field of public health. They include (complex) microbial communities of mainly lactic acid bacteria that are considered beneficial in stimulating a healthy gut microbiota and that promote food safety [1,2]. Most traditional fermented foods are produced by spontaneous fermentation, meaning that no starter culture is added to ferment the raw ingredients. Spontaneous fermentation results in products containing diverse microbial communities. Bacterial strains in these communities can be similar to probiotics . The probiotic properties of these products may be further enhanced by enriching the microbial communities through the addition of known probiotic strains to ensure probiotic activity.
In conclusion, we found that lait caillé harbors a diverse bacterial community of lactic acid bacteria that is stable in terms of composition over multiple rounds of fermentation. Although the biofilm of the lahals is the only inoculum for the lait caillé produced in this study, the bacterial composition of lait caillé differs from that in the biofilms as some strain in the biofilm grow much better in milk than others. The addition of Yoba starter culture to every fermentation cycle of a spontaneously fermented milk product like lait caillé can result in a probiotic product. It is remarkable that even a diverse community such as the bacterial community found in the lahals allows for the temporary inclusion of another species. This knowledge can inform further research aimed at leveraging the benefits of other traditional and widely consumed products supplemented with Yoba starter culture. Future research on traditionally-produced lait caillé may generate evidence of probiotic properties of the microbiota in it and hence of lait caillé itself.