Microbiota composition of dadih - a traditional fermented buffalo milk of West Sumatra

Dadih is an Indonesian traditional spontaneously fermented buffalo milk, produced in West-Sumatra, which is nutritious and has health benefits. The mechanism of action behind the health benefits is largely unknown, but several probiotic strains have been isolated from dadih, which may contribute to its health properties. To identify the composition of its microbiota, two artisanal dadih samples (n = 8) were collected from four producers. The raw buffalo milk used for fermentation was either pasteurized (n = 4) or not (n = 4), and back-slopping was used as a starter-culture (n = 5) or not (n = 3). DNA was extracted from each sample in duplicate and the microbiota composition was determined by 16S-rRNA-gene amplicon-sequencing of the V3-V4 region. PCoA analysis showed clear separation of the samples by producer, but no separation due to pasteurization or use of back-slopping. Lactococcus (52-83%) predominated in all samples, followed by Klebsiella (5-26%), and Lactobacillaceae, Bifidobacterium (particularly high (c. 18%) in the non-pasteurized, back-slopped product from Palupuh), Streptococcus and Leuconostoc. Back-slopping practice correlated significantly with higher abundance of Lactobacillaceae, Pediococcus, species of the order Burkholderiales, and Serratia, but with lower abundance of several other Enterobacteriaceae (including Klebsiella), Streptococcaceae, Staphylococcus and Brachybacterium. Pasteurization was not significantly correlated with the presence of certain members of the final microbiota. Taken together, fermentation results differ significantly from producer to producer and back-slopping practice would be advisable. SIGNIFICANCE AND IMPACT OF THE STUDY: Using state-of-the-art methods we determined the microbiota composition of dadih, an artisanal, traditional fermented buffalo milk of West Sumatra with health benefits. We show that the artisanal practice leaves room for standardization and optimization with respect to the presence of potential pathogenic species in the final product. The Dadih Initiative in Indonesia aims to expand production of this health promoting product, and the findings help to determine important steps for potential food safety issues and good-manufacturing-practices to obtain a safe, nutritious and healthy traditional yoghurt-like functional food.