A novel consortium of Lactobacillus rhamnosus and Streptococcus thermophilus for increased access to functional fermented foods

A novel consortium of Lactobacillus rhamnosus and Streptococcus thermophilus for increased access to functional fermented foods Kort et al. Kort et al. Microb Cell Fact (2015) 14:195 DOI 10.1186/s12934-015-0370-x Kort et al. Microb Cell Fact (2015) 14:195 DOI 10.1186/s12934-015-0370-x Open Access RESEARCH A novel consortium of Lactobacillus rhamnosus and Streptococcus thermophilus for increased access to functional fermented foods Remco Kort1,2,3,4* , Nieke Westerik1,3, L. Mariela Serrano5, François P. Douillard6, Willi Gottstein3, Ivan M. Mukisa7, Coosje J. Tuijn1, Lisa Basten5, Bert Hafkamp5, Wilco C. Meijer5, Bas Teusink3, Willem M. de Vos6,8,9, Gregor Reid10,11 and Wilbert Sybesma1 Abstract Background: The lactic acid bacterium Lactobacillus rhamnosus GG is the most studied probiotic bacterium with proven health benefits upon oral intake, including the alleviation of diarrhea. The mission of the Yoba for Life foundation is to provide impoverished communities in Africa increased access to Lactobacillus rhamnosus GG under the name Lactobacillus rhamnosus yoba 2012, world’s first generic probiotic strain. We have been able to overcome the strain’s limitations to grow in food matrices like milk, by formulating a dried starter consortium with Streptococcus thermophilus that enables the propagation of both strains in milk and other food matrices. The affordable seed culture is used by people in resource-poor communities. Results: We used S. thermophilus C106 as an adjuvant culture for the propagation of L. rhamnosus yoba 2012 in a variety of fermented foods up to concentrations, because of its endogenous proteolytic activity, ability to degrade lactose and other synergistic effects. Subsequently, L. rhamnosus could reach final titers of 1E+09 CFU ml−1, which is sufficient to comply with the recommended daily dose for probiotics. The specific metabolic interactions between the two strains were derived from the full genome sequences of L. rhamnosus GG and S. thermophilus C106. The piliation of the L. rhamnosus yoba 2012, required for epithelial adhesion and inflammatory signaling in the human host, was stable during growth in milk for two rounds of fermentation. Sachets prepared with the two strains, yoba 2012 and C106, retained viability for at least 2 years. Conclusions: A stable dried seed culture has been developed which facilitates local and low-cost production of a wide range of fermented foods that subsequently act as delivery vehicles for beneficial bacteria to communities in east Africa. Keywords: Enrichment, Lactobacillus rhamnosus GG, Lactobacillus rhamnosus yoba 2012, Streptococcus thermophilus C106, Bacterial fermentation, Consortium, Yoghurt, Functional foods, Fermented foods Background Diarrheal diseases and associated malnutrition remain a leading cause of mortality and morbidity of children *Correspondence: 1 Yoba for Life Foundation, Hunzestraat 133‑A, 1079 WB Amsterdam, The Netherlands Full list of author information is available at the end of the article in low-income countries in sub-Saharan Africa [1]. Beneficial bacteria, such as Lactobacillus rhamnosus GG are known to contribute to the reduction of the overall incidence of symptomatic rotavirus associated diarrhea, as reported in a recent meta-analysis [2]. At present, such effective probiotics are not available in sub-Saharan Africa or not affordable to the poor. Other means of ingesting beneficial microbes include fermented foods, of © 2015 Kort et al. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Kort et al. Microb Cell Fact (2015) 14:195 which various forms have a long history in Africa and are broadly acknowledged to contribute to a healthy life style and gastrointestinal wellbeing [3, 4]. Unfortunately, traditional food processing is often hampered by spoilage; in Uganda alone, 27 % of the produced milk is lost due to spillage and spoilage at different stages of the chain [5]. An additional concern is the decline of the consumption of fermented food due to westernization of diets [6, 7]. We reason that access to probiotic cultures for fermentation can contribute to improving health and wealth of people in resource poor countries in multiple ways: (1) increase of shelf life and microbial food safety, (2) reduce spoilage by controlled fermentations, (3) increase the nutritional properties of the fermented foods by delivery of beneficial bacteria, bioactive compounds such as vitamins, and sequestering toxic components, (4) prevent and reduce episodes of diarrhea resulting from the intake of a probiotic strain, and (5) provide incomes for local producers who sell the foods. The ability to propagate probiotics in fermented foods is limited due to legal and biological constraints. On one hand, ownership of intellectual property and a for-profit business model limits sales to premium products. On the other hand, probiotics originating from niches in the intestinal tract often lack the metabolic capabilities to propagate well in food matrices. In addition, the continuous propagation of intestinal isolates in a dairy environment may lead to the selection of mutants with genetic rearrangements, potentially coinciding with a reduction of their probiotic functionality [8]. Recently, we reported on the concept of “generic probiotics”, as a practical solution to create increased access to probiotics for people in resource poor countries [9]. Analogous to generic drugs, we reasoned that patent-expired probiotics are free to be used by other suppliers. We applied this concept of generic probiotics, and after isolating L. rhamnosus GG from a commercially available product [9] we renamed it L. rhamnosus yoba 2012. The failure of the probiotic L. rhamnosus GG strain to grow in milk, results from its inability to degrade casein and lactose [10]. In order to enable propagation of the strain, food matrices should be enriched with either degradable sugars such as glucose, proteolytic enzymes, or partially hydrolyzed nitrogen sources such as yeast extract. All three solutions lead to higher cost and technical complexity. As an alternative low-cost solution we identified a proteolytic strain of S. thermophilus able to degrade casein and lactose that would allow L. rhamnosus yoba 2012 to propagate. In the present work, we aimed at creating a novel bacterial consortium that can be easily distributed and used for local production of fermented foods with increased food safety and nutrition (...truncated)