Interaction between lactic acid bacteria and yeasts in airag, an alcoholic fermented milk
ABSTRACT The interaction between nine lactic acid bacteria (LAB) and five yeast strains isolated from airag of Inner Mongolia Autonomic Region, China was investigated. Three representative LAB and two yeasts showed symbioses were selected and incubated in 10% (w/v) reconstituted skim milk as single and mixed cultures to measure viable count, titratable acidity, ethanol and sugar content every 24 h for 1 week. LAB and yeasts showed high viable counts in the mixed cultures compared to the single cultures. Titratable acidity of the mixed cultures was obviously enhanced compared with that of the single cultures, except for the combinations of Lactobacillus reuteri 940B3 with Saccharomyces cerevisiae 4C and Lactobacillus helveticus 130B4 with Candida kefyr 2Y305. C. kefyr 2Y305 produced large amounts of ethanol (maximum 1.35 g/L), whereas non-lactose-fermenting S. cerevisiae 4C produced large amounts of ethanol only in the mixed cultures. Total glucose and galactose content increased while lactose content decreased in the single cultures of Leuconostoc mesenteroides 6B2081 and Lb. helveticus 130B4. However, both glucose and galactose were completely consumed and lactose was markedly reduced in the mixed cultures with yeasts. The result suggests that yeasts utilize glucose and galactose produced by LAB lactase to promote cell growth.
SourceAvailable from: Wenjun Liu[Show abstract] [Hide abstract]
ABSTRACT: This is the first study on the bacterial and fungal community diversity in 17 tarag samples (naturally fermented dairy products) through a metagenomic approach involving high-throughput pyrosequencing. Our results revealed the presence of a total of 47 bacterial and 43 fungal genera in all tarag samples, in which Lactobacillus and Galactomyces were the predominant genera of bacteria and fungi, respectively. The number of some microbial genera, such as Lactococcus, Acetobacter, Saccharomyces, Trichosporon, and Kluyveromyces, among others, was found to vary between different samples. Altogether, our results showed that the microbial flora in different samples may be stratified by geographic region.Journal of Dairy Science 10/2014; 97(10). DOI:10.3168/jds.2014-8360 · 2.55 Impact Factor
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ABSTRACT: Yak milk dreg is a popular dairy product with a unique flavor which is frequently consumed in Tibet. The aim of this study was to investigate the occurrence and distribution of yeasts in yak milk dreg of Tibet. Ninety-one yeast colonies were isolated from ten yak milk dreg samples, and the isolates belonged to seven genera and ten different species based on the phenotypic characterization and analysis of ITS/5.8S ribosomal DNA (rDNA) gene. The distribution of each species among ten samples was as follows: Kluyveromyces lactis (6/10), Pichia fermentans (6/10), Saccharomyces cerevisiae (6/10), Rhodotorula mucilaginosa (6/10), Kluyveromyces marxianus (5/10), Pichia kudriavzevii (4/10), Torulaspora delbrueckii (2/10), Torulaspora quercuum (2/10), Debaryomyces hansenii (1/10), and Cryptococcus albidus (1/10). The present study reports for the first time the yeast profile in yak milk dreg products of Tibet in China, which provides useful information and yeast strain resource for further studies involving probiotic strain selection and starter culture design for the industrial production of yak milk dreg.Dairy Science and Technology 09/2014; 94(5):455-467. DOI:10.1007/s13594-014-0172-7 · 1.13 Impact Factor
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ABSTRACT: Traditional fermented dairy products are major components of the typical Mongolian diet since ancient times. However, almost all the previous studies on the microbial composition of traditional Mongolian fermented dairy products analyzed food samples from the Chinese Mongolian region and Mongolia but not the Russian Mongolian region. In this study, the bacterial and fungal community diversity of nineteen naturally fermented cow's milk (NFCM) samples from local Mongolian families residing in Kalmykia and Chita of Russia was investigated with pyrosequencing. Firmicutes and Ascomycota were the predominant phyla respectively for bacteria and fungi. The abundance of the bacterial phylum Acidobacteria was considerably different between the samples from the two regions. At genus level, Lactobacillus and Pichia were the predominating bacterial and fungal genera, respectively, while six bacterial genera significantly differed between the Kalmykia (enrichment of Aeromonas, Bacillus, Clostridium, Streptococcus, Vogesella) and Chita (enrichment of Lactococcus) samples. The results of principal coordinate analysis (PCoA) based on the bacterial or fungal composition of the Kalmykia and Chita samples revealed a different microbiota structure between the samples collected in these two locations. The redundancy analysis (RDA) identified 60 bacterial and 21 fungal OTUs as the key variables responsible for such microbiota structural difference. Our results suggest that structural differences existed in the microbiota of NFCM between Kalmykia and Chita. The difference in geographic environment may be an important factor influencing the microbial diversity of NFCM made by the Mongolians in Russia.BMC Microbiology 12/2015; 15(1). DOI:10.1186/s12866-015-0385-9 · 2.98 Impact Factor