Preliminary assessment of bacterial diversity of Indonesian naturally-fermented milk products by pyrosequencing — ASN Events
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Preliminary assessment of bacterial diversity of Indonesian naturally-fermented milk products by pyrosequencing (#430)

Yoga Jatmiko 1 2 , Gordon Howarth 1 3 , Mary Barton 4
  1. Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia
  2. Biology Department, University of Brawijaya, Malang, East Java, Indonesia
  3. Department of Gastroenterology,, Women’s and Children’s Hospital, North Adelaide, South Australia, Australia
  4. School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia

This work represents the first study of bacterial communities in the Indonesian naturally-fermented milk products, dadih and dangke. Dadih is manufactured using unpasteurized buffalo milk, after which it is fermented for three days. To produce dangke, heat-treated cow or buffalo milk is coagulated using papaya latex and then the curd is pressed (without maturation). Pyrosequencing of tagged amplicons of the V1-V3 regions of the 16S rDNA and Operational Taxonomic Unit-based (OTU-based) analysis were applied to obtain an overall approximation of the bacterial composition in dadih and dangke; and secondly, to elucidate possible differences between fermentation periods of dadih and dangke production (cow milk: A, and buffalo milk: B and C). Pyrosequencing analysis revealed a high bacterial diversity in both products. Three phyla (bacteroidetes, firmicutes and proteobacteria) were identified in both products, and 18 genera from dadih and 19 genera from dangke were defined. In dadih, Lactococcus (22.9 – 60.7% of sequences) was the predominant genus, followed by Enterobacteriaceae and Acinetobacter. The abundance of Lactococcus throughout the fermentation stages increased remarkably, with a concomitant decrease in the number of sequences belonging to the Enterobacteriaceae family, while Acinetobacter abundance remained constant. Dangke prepared from cow’s milk revealed a diverse bacterial diversity (producer A). OTU analysis identified a set of taxa (Lactococcus,20.5%; Lactobacillus, 18.5%; Streptococcus, 17.1%; Enterococcus, 15.5%; Leuconostoc, 9.7%; and unclassified genera belonging to the Enterobacteriaceae family, 6.9%) that would represent the core components of dangke sourced from cow’s milk. The Enterobacteriaceae family was the predominant taxa in dangke-producer B and C. Enterococcus (0.1% of sequences) was the only lactic acid bacteria detected in dangke-producer B; meanwhile Lactococcus (13.3% of sequences) and Enterococcus (0.5% of sequences) were identified in producer C. The role of lactic acid bacteria is important, not only in developing product quality, but also in improving product safety. Although taxa belonging to important milk-borne diseases were not found, a detailed understanding of the Enterobacteriaceae family associated with the fermentation process is required.

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