Rob, a traditional fermented milk from South Sudan: dynamics of the microbial community composition, microbial interactions and consortia functionality

Rob is a traditional spontaneous fermented milk that is widely consumed in South Sudan. Rob fermentation relies on a complex microbial community of lactic acid bacteria (LAB) and yeast. Spontaneous fermentations are unpredictable and could result in inconsistent quality. To improve the predictability and the quality of Rob, it is essential to understand the factors that shape the microbial community, the interactions between the microorganisms and their role in the fermentation process. In particular, the role of yeast and its interaction with LAB as well as the role of bacteriophages in a stable microbial community are still unclear. This study aims to i) understand the dynamics in the microbial community composition in Rob, ii) identify the microorganisms in the fermentation as well as their interactions and iii) understand their contribution to product functionality. The dynamics in the microbial community composition will be studied using amplicon sequencing and metagenome sequencing. Afterwards, strains will be isolated and characterized. Microbial interactions will be studied in simple model systems and synthetic Rob communities will be built. The project will deliver ecological insight in the complex communities in this product. This delivers design principles for novel processes to manufacture safe, healthy and good tasting Rob.