Evaluation of Yeast Diversity in Dadih and Dangke Using PCR-RFLP of Internal Transcribed Spacer Region

Abstract

The dominant indigenous microbes, such as lactic acid bacteria group, mainly determine the quality of naturally fermented milk products. Yeasts have also contributed to the fermentation development, especially in determining the organoleptic or physicochemical characteristics of the products. This study was aimed to evaluate the diversity of yeasts in the naturally fermented milk products from Indonesia, which were dadih and dangke by using PCR-RFLP of ITS region. Two dadih samples used with one sample were collected in three consecutive days. Dangke samples consisted of three made from buffalo milk (sample A-C), and sample D was from cow’s milk. The isolated yeasts were further characterized genotypically using RFLP analysis of the ITS region. The representative isolates of each cluster as a result of the restriction pattern obtained with HinfI and HaeIII enzymes were further identified. A total of 37 yeast isolates (17 isolates from dadih and 22 isolates from dangke) were grouped into three clusters based on the band pattern of RFLP analysis. Based on DNA sequencing analysis, the three species were identified as Saccharomyces cerevisiae (group I), Candida metapsilosis (group II) and Kluyveromyces marxianus (group III). Saccharomyces cerevisiae and Kluyveromyces marxianus were found in both dadih and dangke samples. Unfortunately, yeasts were not detected in dangke samples A and C. Candida metapsilosis was found frequently in dadih, while Saccharomyces cerevisiae was the dominant species in dangke. Further investigations are needed to shed light on microbial dynamics since the changes in the abundance and type of microbiota during the fermentation process play a pivotal role in the quality of the final products.

Characterization of Dadih: Traditional Fermented Buffalo Milk of Minangkabau

“…The resulting lactic acid decreases the pH value of buffalo milk and contributes to protein precipitation or coagulation of buffalo milk, so the curd or dadih is formed. Decreasing pH value from 6.92 (raw buffalo milk) to 4.65 after 2 days of dadih fermentation was observed [32]. Through carbohydrate catabolism, small quantities of flavor compounds are also formed through the volatile fatty acids, ethanol, acetoin, acetic acid, butanone, diacetyl, and acetaldehyde [29].…”

“…A higher abundance of species of the order Serratia and Burkholderiales, and a lower abundance of Brachybacterium were found in dadih with the back-slopping method [40]. Three yeast species, namely Saccharomyces cerevisiae, Candida metapsilosis, and Kluyveromyces marxianus were found in dadih with C. metapsilosis as the most predominant species [32]. The different types of yeast in dadih, such as Candida stelimalicola and Pichia jadinii, were also reported [41].…”

“…Candida sp., including C. metapsilosis, are normally found in the gastrointestinal tract, but they are also known as opportunistic pathogens which may be considered as the cause of disseminated candidiasis [42]. C. metapsilosis was isolated in the inner part of bamboo tubes of dadih [32]. A study reported that C. metapsilosis was found not only dadih, but also in Chicha, a spontaneously fermented beverage, made from maize [43].…”