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Identification of yeasts and evaluation of their distribution in Taiwanese Kefir and Viili starters.Journal of Dairy Science Oct 2008The objective of the present study was to investigate yeast communities in kefir grains and viili starters in Taiwan through conventional microbiological cultivation and...
The objective of the present study was to investigate yeast communities in kefir grains and viili starters in Taiwan through conventional microbiological cultivation and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The DNA sequencing was used as a validity technique to ensure that all isolates within each group belonged to just one species, and to confirm the identified results of PCR-DGGE. Results indicated that a combination of conventional microbiological cultivation with PCR-DGGE and sequencing could successfully identify 4 yeast species from both types of cultures in Taiwan. Kluyveromyces marxianus, Saccharomyces turicensis, and Pichia fermentans were found in Taiwanese kefir grains with a distribution of 76, 22, and 2%, respectively, whereas Klu. marxianus, Saccharomyces unisporus and P. fermentans were identified in viili starters corresponding to 58, 11, and 31% of the total cell counts, respectively. Furthermore, the culture-independent method was applied to identify the yeast species using DGGE. Only 2 yeast species, Klu. marxianus and S. turicensis, were found in kefir grains and 2, Klu. marxianus and P. fermentans, in viili starters. These results suggest that in samples containing multiple species, PCR-DGGE may fail to detect some species. Sequences of yeast isolates reported in this study have been deposited in the GenBank database under accession nos. DQ139802, AF398485, DQ377652, and AY007920.
Topics: Cultured Milk Products; Food Microbiology; Microbiological Techniques; Molecular Sequence Data; Polymerase Chain Reaction; Taiwan; Yeasts
PubMed: 18832201
DOI: 10.3168/jds.2007-0468 -
Journal of Dairy Science Feb 2017The objective of this study was to identify species of yeasts in samples of high moisture corn (HMC) and corn silage (CS) collected from farms throughout the United...
The objective of this study was to identify species of yeasts in samples of high moisture corn (HMC) and corn silage (CS) collected from farms throughout the United States. Samples were plated and colonies were isolated for identification using DNA analysis. Randomly selected colonies were also identified by fatty acid methyl esters (FAME) and by physiological substrate profiling (ID 32C). For CS, Candida ethanolica, Saccharomyces bulderi, Pichia anomala, Kazachstania unispora, and Saccharomyces cerevisiae were the predominant yeasts. Pichia anomala, Issatchenkia orientalis, S. cerevisiae, and Pichia fermentans were the prevalent species in HMC. The 3 identification methods were in agreement at the species level for 16.6% of the isolates and showed no agreement for 25.7%. Agreement in species identification between ID 32C and DNA analysis, FAME and ID 32C, and FAME and DNA analysis was 41.1, 14.4, and 2.2%, respectively. Pichia anomala and I. orientalis were able to grow on lactic acid, whereas S. cerevisiae metabolized sugars (galactose, sucrose, and glucose) but failed to use lactic acid. The yeast diversity in CS and HMC varied due to type of feed and location. Differences in species assignments were seen among methods, but identification using substrate profiling generally corresponded with that based on DNA analysis. These findings provide information about the species that may be expected in silages, and this knowledge may lead to interventions that control unwanted yeasts.
Topics: Animals; Fermentation; Saccharomyces cerevisiae; Saccharomycetales; Silage; United States; Yeasts; Zea mays
PubMed: 27889126
DOI: 10.3168/jds.2016-11450 -
Frontiers in Microbiology 2019Raw material is important for flavors in fermented foods. Here, the effect of hulless barley on the microbiota in Chinese liquor was studied using two main cultivars (...
Raw material is important for flavors in fermented foods. Here, the effect of hulless barley on the microbiota in Chinese liquor was studied using two main cultivars ( and ). Six genera (, and ) were identified as flavor producers. , mainly correlated with esters, dominated in , and , mainly correlated with carbonyls, dominated in . The Mantel test indicated reducing sugar drove the succession of microbiota (: = 0.001; : = 0.006). Especially, glucose ( = 0.0226) and fructose ( = 0.0168) presented the most significant correlations with and , respectively. The simulative fermentation confirmed QK2 grew better in with more fructose, whereas PF grew better in with more glucose. This work highlighted the effect of raw material on microbiota, which would be beneficial for regulating the quality of fermented foods.
PubMed: 31333623
DOI: 10.3389/fmicb.2019.01520 -
PloS One 2020Only quite recently, we have shown that yeast strains Clavispora lusitaniae 146 and Pichia fermentans 27 can act as efficient biocontrol agents for combating postharvest...
Only quite recently, we have shown that yeast strains Clavispora lusitaniae 146 and Pichia fermentans 27 can act as efficient biocontrol agents for combating postharvest fungal diseases in lemons. During postharvest and storage conditions, microorganisms are subject to different stress factors that could affect both their survival and their protective capacity. Understanding the tolerance of yeasts to environmental stress factors could support the future development and commercial application of biological control formulations based on such organisms. Thus, the impact of different stressors on the viability and protection efficiency of C. lusitaniae strain 146 and P. fermentans strain 27 was evaluated, and the yeasts were subjected to oxidative stress, thermal treatments, exposure to NaOCl, osmotic stress, and ultraviolet irradiation. Candida oleophila strain O served as the reference control. C. lusitaniae 146 was more resistant to H2O2 in plate assays; however, in liquid media there was no significant difference to the other strains. Strain 146 was less affected by NaOCl, being able to survive with 300 ppm. P. fermentans 27 was the strain most heavily affected by osmotic pressure, while strains 146 and strain O showed a similar adaptation. UV-B irradiation severely affected C. oleophila and P. fermentans, while C. lusitaniae was the most resistant. Strains 146 and 27 were similarly tolerant to thermal shocks, compared to the reference strain, which was less viable. In in vivo tests, exposure to 10 mM H2O2, 45°C or 200 ppm NaOCl prior to fruit inoculation, reduced the antagonistic activity against the pathogen Penicillium digitatum. However, in no case was the biocontrol efficiency reduced to less than 50%. As C. lusitaniae 146 demonstrated a great potential to combat P. digitatum under a wide range of conditions, the organism is a promising candidate as an effective and valuable alternative to toxic fungicides.
Topics: Citrus; Microbial Viability; Oxidative Stress; Pest Control, Biological; Saccharomycetales; Temperature
PubMed: 32946508
DOI: 10.1371/journal.pone.0239432 -
Journal of Applied Microbiology Aug 2018To investigate the volatile flavour components (VFCs), microbiota and their correlations of three categories of sufu, a Chinese fermented soybean food.
AIM
To investigate the volatile flavour components (VFCs), microbiota and their correlations of three categories of sufu, a Chinese fermented soybean food.
METHODS AND RESULTS
The VFCs were analyzed by headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography and mass spectrometry. A total of 141 VFCs were tentatively identified, in which 12 esters, eight aldehydes, five alcohols and nine miscellaneous compounds were recognized as the characteristic VFCs through the relative odour activity value. The complex microbial community was revealed by Illumina MiSeq sequencing. Among the total 202 bacteria and 125 fungi species identified, 16 bacteria and 7 fungi species were revealed as dominant community members. Furthermore, the VFC-microbiota correlation was characterized by Spearman's rank correlation coefficients (ρ). Based on the positive VFC-microbiota correlation, two bacterial species and three fungal species were selected as potential flavour-producing microbiota.
CONCLUSIONS
A variety of VFCs and complicated microbiota were observed in the three categories of sufu. Lactococcus lactis, Sphingobacterium sp., Pichia fermentans, Kodamaea ohmeri and Saccharomyces rouxii were the potential flavour-producing microbiota.
SIGNIFICANCE AND IMPACT OF THE STUDY
The preliminary results would be useful for designing starter cultures to produce sufu with desirable sensory properties, consistent flavour and shorter ripening time. Furthermore, these results will also provide a new insight to improve the flavour quality of traditional fermented soybean food.
PubMed: 30133098
DOI: 10.1111/jam.14078 -
Scientific Reports Jan 2024Extracellular vesicles (EVs) are lipid-bilayered particles, containing various biomolecules, including nucleic acids, lipids, and proteins, released by cells from all...
Extracellular vesicles (EVs) are lipid-bilayered particles, containing various biomolecules, including nucleic acids, lipids, and proteins, released by cells from all the domains of life and performing multiple communication functions. Evidence suggests that the interaction between host immune cells and fungal EVs induces modulation of the immune system. Most of the studies on fungal EVs have been conducted in the context of fungal infections; therefore, there is a knowledge gap in what concerns the production of EVs by yeasts in other contexts rather than infection and that may affect human health. In this work, we characterized EVs obtained by Saccharomyces cerevisiae and Pichia fermentans strains isolated from a fermented milk product with probiotic properties. The immunomodulation abilities of EVs produced by these strains have been studied in vitro through immune assays after internalization from human monocyte-derived dendritic cells. Results showed a significant reduction in antigen presentation activity of dendritic cells treated with the fermented milk EVs. The small RNA fraction of EVs contained mainly yeast mRNA sequences, with a few molecular functions enriched in strains of two different species isolated from the fermented milk. Our results suggest that one of the mechanisms behind the anti-inflammatory properties of probiotic foods could be mediated by the interactions of human immune cells with yeast EVs.
Topics: Humans; Saccharomyces cerevisiae; Yeast, Dried; Extracellular Vesicles; Fermented Beverages; Cultured Milk Products
PubMed: 38184708
DOI: 10.1038/s41598-024-51370-7 -
Frontiers in Microbiology 2020To investigate the effect of yeasts on Kazak cheese quality and flavor, three isolated yeasts ( A2, A11, and A19) were used to ferment cheeses and designated as StC,...
To investigate the effect of yeasts on Kazak cheese quality and flavor, three isolated yeasts ( A2, A11, and A19) were used to ferment cheeses and designated as StC, LhC, and WcC, respectively. The cheese fermented with a commercial lactic acid starter without adding yeast was used as control named LrC. The results showed that the texture of cheese added with yeasts were more brittle. A2 contributed to the formation of free amino acids and organic acids, especially glutamate and lactic acid. Moreover, A2 provides cheese with onion, oily, and floral aromas. Furthermore, A11 promotes a strong brandy, herbaceous, and onion flavor. Although no significant aroma change was observed in PfC, it promoted the production of acetic acid, isoamyl acetate, and phenethyl acetate. These results indicate that yeasts are important auxiliary starters for cheese production.
PubMed: 33391244
DOI: 10.3389/fmicb.2020.614208 -
Journal of Applied Microbiology Nov 2007This study evaluated the quality and possible hygiene risks related to farm-made silages by analysing the presence and number of micro-organisms that influence the...
AIMS
This study evaluated the quality and possible hygiene risks related to farm-made silages by analysing the presence and number of micro-organisms that influence the preservation and safety in samples from four Italian regions.
METHODS AND RESULTS
Lactic acid bacteria, clostridia, lactate-fermenting yeasts and propionibacteria (PAB) were isolated and identified by random amplified polymorphic DNA PCR, sequencing of the V2-V3 16S rRNA gene region, 5.8S-ITS rDNA RFLP and species-specific PCR. The Lactobacillus plantarum cluster was the most numerous and comprised strains mostly isolated from alfalfa silage. The Lactobacillus buchneri cluster, second in number, comprised isolates from both alfalfa and maize silage. Anaerobic spore formers were assigned to the species Clostridium baratii, Clostridium beijerinkii, Clostridium butyricum, Clostridium perfringens, Clostridium saccharolyticum, Clostridium tyrobutyricum and Paenibacillus macerans. Yeast isolates were identified as Candida apicola, Candida mesenterica and Pichia fermentans. PAB strains, detected only in unifeed, were all identified as Propionibacterium acidipropionici.
CONCLUSIONS
The occurrence of spoiling micro-organisms was frequent and the possibility of contamination by potentially pathogenic clostridia was demonstrated.
SIGNIFICANCE AND IMPACT OF THE STUDY
The results suggest the need for improved ensiling practices and appropriate control measures to safeguard the hygienic and nutritional quality of silages produced in farms.
Topics: Animals; Bacteria; Candida; Clostridium; Colony Count, Microbial; Fermentation; Food Microbiology; Italy; Lactobacillus plantarum; Medicago sativa; Pichia; Propionibacterium; Random Amplified Polymorphic DNA Technique; Silage; Yeasts; Zea mays
PubMed: 17953581
DOI: 10.1111/j.1365-2672.2007.03416.x -
Frontiers in Microbiology 2016The geographically isolated region of the Yaghnob Valley, Tajikistan, has allowed its inhabitants to maintain a unique culture and lifestyle. Their fermented goat milk...
The geographically isolated region of the Yaghnob Valley, Tajikistan, has allowed its inhabitants to maintain a unique culture and lifestyle. Their fermented goat milk constitutes one of the staple foods for the Yaghnob population, and is produced by backslopping, i.e., using the previous fermentation batch to inoculate the new one. This study addresses the yeast composition of the fermented milk, assessing genotypic, and phenotypic properties. The 52 isolates included in this study revealed small species diversity, belonging to , and one . The strains showed two different genotypes, one of which never described previously. The two genetically different groups also differed significantly in several phenotypic characteristics, such as tolerance toward high temperatures, low pH, and presence of acid. Microsatellite analysis of the strains from this study, compared to 350 previously described strains, attributed the Yaghnobi to two different ancestry origins, both distinct from the wine and beer strains, and similar to strains isolated from human and insects feces, suggesting a peculiar origin of these strains, and the existence of a gut reservoir for . Our work constitutes a foundation for strain selection for future applications as starter cultures in food fermentations. This work is the first ever on yeast diversity from fermented milk of the previously unexplored area of the Yaghnob Valley.
PubMed: 27857705
DOI: 10.3389/fmicb.2016.01690 -
Ultrasonics Sonochemistry Mar 2012The study determined the efficacy of Dynashock wave power ultrasound as an alternative processing technique for apple juice against a number of pathogenic and spoilage...
The study determined the efficacy of Dynashock wave power ultrasound as an alternative processing technique for apple juice against a number of pathogenic and spoilage microorganisms. The effects of several implicit, intrinsic and extrinsic properties on the Dynashock wave inactivation of the microorganisms were also investigated. Results showed that acid adaptation increased the resistance of Escherichia coli O157:H7 and Salmonella spp. but decreased that of Listeria monocytogenes. Spoilage yeast mixed inoculum composed of Debaryomyces hansenii, Torulaspora delbrueckii, Clavispora lusitaniae, Pichia fermentans and Saccharomyces cerevisiae was found to be more resistant than any of the adapted or non-adapted pathogens. Among the individual, acid-adapted E. coli O157:H7, the MN-28 isolate was found most resistant; while three other individual isolates had greater resistance than the composited E. coli inoculum. Increased in pulp content decreased the efficacy of Dynashock waves, but co-treatment with ultraviolet-C rays significantly enhanced inactivation in the cloudy apple juice. The results demonstrated the potential of Dynashock wave technology, together with other antimicrobial hurdles as alternative juice processing technique/s.
Topics: Bacteria; Beverages; Hydrogen-Ion Concentration; Malus; Microbial Viability; Temperature; Ultrasonics; Ultraviolet Rays; Yeasts
PubMed: 21802974
DOI: 10.1016/j.ultsonch.2011.06.003