Identification of Yeasts and Evaluation of their Distribution in Taiwanese Kefir and Viili Starters

Wang, S.-Y.; Chen, H.C.; Liu, Je-Ruei; Lin, Yu‐Te; Chen, M.J.

doi:10.3168/jds.2007-0468

Cited by 70 publications

(63 citation statements)

References 38 publications

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“…Interestingly, although Kazachstania is commonly detected in TKGs as well as other KG lineages, it is absent in our samples. On the whole, yeasts were characterized by a high diversity over the whole family of KGs but a relatively low diversity in a single KG [11], [32]–[34]. In addition, like Yarrowia , some species are solely associated with one or two lineages of KGs [3], [11].…”

Section: Discussionmentioning

confidence: 99%

Fine Structure of Tibetan Kefir Grains and Their Yeast Distribution, Diversity, and Shift

Wang

Sun

et al. 2014

PLoS ONE

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Tibetan kefir grains (TKGs), a kind of natural starter for fermented milk in Tibet, China, host various microorganisms of lactic acid bacteria, yeasts, and occasionally acetic acid bacteria in a polysaccharide/protein matrix. In the present study, the fine structure of TKGs was studied to shed light on this unusual symbiosis with stereomicroscopy and thin sections. The results reveal that TKGs consist of numerous small grain units, which are characterized by a hollow globular structure with a diameter between 2.0 and 9.0 mm and a wall thickness of approximately 200 µm. A polyhedron-like net structure, formed mainly by the bacteria, was observed in the wall of the grain units, which has not been reported previously to our knowledge. Towards the inside of the grain unit, the polyhedron-like net structures became gradually larger in diameter and fewer in number. Such fine structures may play a crucial role in the stability of the grains. Subsequently, the distribution, diversity, and shift of yeasts in TKGs were investigated based on thin section, scanning electron microscopy, cloning and sequencing of D1/D2 of the 26S rRNA gene, real-time quantitative PCR, and in situ hybridization with specific fluorescence-labeled oligonucleotide probes. These show that (i) yeasts appear to localize on the outer surface of the grains and grow normally together to form colonies embedded in the bacterial community; (ii) the diversity of yeasts is relatively low on genus level with three dominant species – Saccharomyces cerevisiae, Kluyveromyces marxianus, and Yarrowia lipolytica; (iii) S. cerevisiae is the stable predominant yeast species, while the composition of Kluyveromyces and Yarrowia are subject to change over time. Our results indicate that TKGs are relatively stable in structure, and culture conditions to some extent shape the microbial community and interaction in kefir grains. These findings pave the way for further study of the specific symbiotic associations between S. cerevisiae and Lactobacillus bacteria in TKGs.

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Section: Discussionmentioning

confidence: 99%

Fine Structure of Tibetan Kefir Grains and Their Yeast Distribution, Diversity, and Shift

Wang

Sun

et al. 2014

PLoS ONE

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“…Thus, culture-independent techniques have the potential to provide a more accurate and in-depth analysis. Although culture-independent techniques such as Sanger sequencing [12], [16], [20], [21] and DGGE [14], [15], [22] have been employed to explore the kefir population, the application of high-throughput DNA sequencing to investigate such microbial ecosystems has been a particularly significant development. This strategy has been employed to study the microbial composition of a number of fermented food environments such as cheese [23], [24], fermented fish [25], [26], fermented vegetables [27], rice bran [28] and pearl millet slurry [29].…”

Section: Introductionmentioning

confidence: 99%

Sequencing-Based Analysis of the Bacterial and Fungal Composition of Kefir Grains and Milks from Multiple Sources

et al. 2013

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Kefir is a fermented milk-based beverage to which a number of health-promoting properties have been attributed. The microbes responsible for the fermentation of milk to produce kefir consist of a complex association of bacteria and yeasts, bound within a polysaccharide matrix, known as the kefir grain. The consistency of this microbial population, and that present in the resultant beverage, has been the subject of a number of previous, almost exclusively culture-based, studies which have indicated differences depending on geographical location and culture conditions. However, culture-based identification studies are limited by virtue of only detecting species with the ability to grow on the specific medium used and thus culture-independent, molecular-based techniques offer the potential for a more comprehensive analysis of such communities. Here we describe a detailed investigation of the microbial population, both bacterial and fungal, of kefir, using high-throughput sequencing to analyse 25 kefir milks and associated grains sourced from 8 geographically distinct regions. This is the first occasion that this technology has been employed to investigate the fungal component of these populations or to reveal the microbial composition of such an extensive number of kefir grains or milks. As a result several genera and species not previously identified in kefir were revealed. Our analysis shows that the bacterial populations in kefir are dominated by 2 phyla, the Firmicutes and the Proteobacteria. It was also established that the fungal populations of kefir were dominated by the genera Kazachstania, Kluyveromyces and Naumovozyma, but that a variable sub-dominant population also exists.

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“…The LAB isolated from kefir grains were identified as Lactobacillus kefiri , Lactobacillus kefiranofaciens , Leuconostoc mesenteroides and Lactococcus lactis (Chen et al. 2008) and the yeasts were identified as Kluyveromyces marxianus and Pichia fermentans (Wang et al. 2008).…”

Section: Methodsmentioning

confidence: 99%

Process Optimization for a Novel Kefir Candy With High Probiotic Viability

Chen

Kuo

Shiu

et al. 2011

J Food Process Engineering

Self Cite

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Kefir, a beverage produced by the action of lactic acid bacteria (LAB), yeasts and acetic acid bacteria on milk, has a long tradition of offering health benefits. The objective of this research was to optimize the best formula for producing the kefir candy with maximum viabilities of LAB and yeasts using the response surface modeling and the sequential quadratic programming (SQP) method. In this study, milk was mixed with 5% kefir grains and incubated at 20C for 24 h. The samples were blended with lyoprotectants (galactose, skim milk powder [SMP] and sucrose), freeze‐dried and then mixed with sweeteners and compressed to form candies. The ratio of the lyoprotectants was determined using response surface modeling for constructing a response surface model and then using an SQP method to optimize the model. Optimization results indicated that kefir containing galactose, sucrose and SMP at 4.53, 7.0 and 5.03% (w/v), respectively, produced a chewable tablet with the highest viability of the microorganisms investigated. A relatively higher survival of microorganisms could be achieved by placing the kefir candy product in a glass bottle with deoxidant and desiccant at 4C. PRACTICAL APPLICATIONS A number of novel fermented dairy products have been developed and marketed under the concept of probiotic products, but few of these products were associated with confectionary goods. The kefir candy created in the present study with high viable cell counts (106–107 cfu/g) after extended storage (up to 2 months) provides a flavorful option to offer the health benefits of probiotics. This study not only provides an opportunity to resolve the difficulty of kefir commercialization due to its post‐acidity and gas production but also increases the variety of dairy products in the market.

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Identification of Yeasts and Evaluation of their Distribution in Taiwanese Kefir and Viili Starters

Cited by 70 publications

References 38 publications

Fine Structure of Tibetan Kefir Grains and Their Yeast Distribution, Diversity, and Shift

Fine Structure of Tibetan Kefir Grains and Their Yeast Distribution, Diversity, and Shift

Sequencing-Based Analysis of the Bacterial and Fungal Composition of Kefir Grains and Milks from Multiple Sources

Process Optimization for a Novel Kefir Candy With High Probiotic Viability

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