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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 -
Evaluation of the efficacy of commercial protective cultures against mold and yeast in queso fresco.Journal of Dairy Science Nov 2020In this study, we evaluated the efficacy of 3 commercial protective cultures designated PC1 (Lactobacillus spp.), PC2 (Lactobacillus rhamnosus), and PC3...
In this study, we evaluated the efficacy of 3 commercial protective cultures designated PC1 (Lactobacillus spp.), PC2 (Lactobacillus rhamnosus), and PC3 (Lactobacillus rhamnosus) as biopreservatives in queso fresco (QF) against 9 yeast strains (Candida zeylanoides, Clavispora lusitaniae, Debaryomyces hansenii, Debaryomyces prosopidis, Kluyveromyces marxianus, Meyerozyma guilliermondii, Pichia fermentans, Rhodotorula mucilaginosa, and Torulaspora delbrueckii) and 11 mold strains (Aspergillus cibarius, Aureobasidium pullulans, Penicillium chrysogenum, Penicillium citrinum, Penicillium commune, Penicillium decumbens, Penicillium roqueforti, Mucor genevensis, Mucor racemosus, Phoma dimorpha, and Trichoderma amazonicum). All fungal spoilage strains were previously isolated from dairy processing environments. A positive control (C) with no protective culture was included. Fungal spoilage organisms were inoculated on cheese surfaces at an inoculum level of 20 cfu/g, and cheeses were stored at 6 ± 2°C throughout the study. For yeast enumeration, cheeses were sampled on d 0, 7, 14, and 21 postinoculation. Significant inhibition was detected for each yeast strain by comparing yeast counts for each cheese treated with protective culture against the control cheese using one-way ANOVA with Bonferroni correction performed individually at d 7, 14, and 21 postinoculation. Mold growth was visually observed and imaged weekly through 70 d postinoculation. Whereas PC3 inhibited Cl. lusitaniae, Mey. guilliermondii, and Ph. dimorpha, PC2 inhibited the outgrowth of Cl. lusitaniae, D. hansenii, and Ph. dimorpha. Protective culture 1 had the broadest spectrum of efficacy across yeast and molds, delaying spoilage caused by 4 distinct yeast strains (Cl. lusitaniae, D. hansenii, D. prosopidis, and Mey. guilliermondii), and inhibiting visible growth of 2 mold strains (P. chrysogenum and Ph. dimorpha). Results demonstrated that commercial protective cultures vary in performance, as indicated by the breadth of mold and yeast inhibition at both the genus and species level. This study suggests that manufacturers looking into using protective cultures should investigate their efficacy against specific fungal strains of concern.
Topics: Animals; Cheese; Food Contamination; Food Microbiology; Fungi; Lactobacillus; Yeasts
PubMed: 32896415
DOI: 10.3168/jds.2020-18769 -
Frontiers in Microbiology 2020Hundreds of sourdoughs have been investigated in the last decades. However, many studies used a culture-dependent and/or culture-independent microbiological approach...
Hundreds of sourdoughs have been investigated in the last decades. However, many studies used a culture-dependent and/or culture-independent microbiological approach [mainly based on denaturing gradient gel electrophoresis (DGGE) of PCR amplicons], seldomly combined with a metabolite target analysis, to characterize the microbial species communities of the sourdoughs examined. Moreover, attention was mainly paid on lactic acid bacteria (LAB) and yeast species. In the present study, distinct household-scale (including an artisan lambic brewery) and artisan bakery-scale backslopped sourdoughs (17 in total), obtained from different regions (Belgium, France, United Kingdom, and USA), were examined through a multiphasic approach, encompassing a culture-dependent analysis [targeting LAB, acetic acid bacteria (AAB), and yeasts], different culture-independent techniques [rRNA-PCR-DGGE, metagenetics, and metagenomics (four bakery sourdoughs)], and metabolite target analysis. It turned out that the microbial species diversity of the sourdoughs was influenced by the house microbiota of the producer. Further, when the producer made use of different flours, the sourdoughs harbored similar microbial communities, independent of the flour used. AAB were only present in the Belgian sourdoughs, which might again be related to the processing environment. (formerly known as ) was the prevalent LAB species of the eight sourdoughs produced by two of the three bakeries of different countries analyzed. These sourdoughs were characterized by the presence of either or . Moreover, the presence of was positively correlated with the production of mannitol and negatively correlated with the presence of other LAB or AAB species. Sourdoughs produced in an artisan lambic brewery were characterized by the presence of the yeast species and . One household sourdough was characterized by the presence of uncommon species, such as and . Metagenomic sequencing allowed the detection of many more LAB and AAB species than the other methods applied, which opened new frontiers for the understanding of the microbial communities involved during sourdough production processes.
PubMed: 32760353
DOI: 10.3389/fmicb.2020.01212 -
Journal of Food Science and Technology Sep 2020Different types of yeasts and lactic acid bacteria dominate in spontaneously fermented products (food, beverages, and condiments) that are commonly consumed in Ethiopia....
Different types of yeasts and lactic acid bacteria dominate in spontaneously fermented products (food, beverages, and condiments) that are commonly consumed in Ethiopia. The aim of this study was to identify efficient fermentative yeasts from fermented foods, fermented beverages, honey and molasses using genotypic methods. Out of the 70 samples tested, 180 distinct wild yeast isolates were recovered. A total of 23 isolates were selected for genomic analysis based on their basis of biomass yield, fermentation capacity, and leavening performance. The nucleotide sequence analysis of the internal transcribed spacer ITS-5.8S rDNA region revealed that the indigenous yeast isolates had close relatedness to , , , and with greater than 97% nucleotide similarity. The study shows a high diversity of indigenous wild yeasts in fermented products and that potent strains had higher biomass yield, good gas production and remarkable leavening capacity that indicates their inherent potential for use in the baking industry.
PubMed: 32713962
DOI: 10.1007/s13197-020-04377-7 -
Food Chemistry Dec 2020A selected Pichia fermentans strain was simultaneously and sequentially inoculated in synthetic and real juice with S. cerevisiae strains of different antagonistic...
A selected Pichia fermentans strain was simultaneously and sequentially inoculated in synthetic and real juice with S. cerevisiae strains of different antagonistic activities in a ratio 1:1 to observe the correlation between varietal odorants and glycosidase activities. Fermentations using pure S. cerevisiae strains were used for comparison. Yeast biomass and glycosidase activities were monitored, varietal odorants were detected using HS-SPME-GC/MS during fermentation. The final wine aroma attributes were analyzed by trained panelists. Results showed that co-inoculation with high antagonistic S. cerevisiae resulted in higher glycosidase activities than others. Pearson correlation analysis indicated that yeast biomass was positively related to glycosidase activities during fermentation. The increase in glycosidase activities was the main reason for the higher production of terpenes and C-norisoprenoids, and for the lower C compound content, which lead to superior fruity and floral aromas in the final wine samples of the high antagonistic S. cerevisiae group.
Topics: Fermentation; Fruit; Fruit and Vegetable Juices; Fungal Proteins; Gas Chromatography-Mass Spectrometry; Glycoside Hydrolases; Norisoprenoids; Odorants; Pichia; Saccharomyces cerevisiae; Terpenes; Wine
PubMed: 32619948
DOI: 10.1016/j.foodchem.2020.127426 -
Animal Science Journal = Nihon Chikusan... 2020To investigate the yeast population dynamics during air exposure in total mixed ration (TMR) silage containing sweet potato residue. TMR were ensiled in laboratory silos...
To investigate the yeast population dynamics during air exposure in total mixed ration (TMR) silage containing sweet potato residue. TMR were ensiled in laboratory silos (1 kg) with or without two lactic acid bacteria strains, Lactobacillus plantarum (LP), and Lactobacillus amylovorus (LA). Fermentation characteristics were measured and yeast population was investigated by ITS1 region gene sequencing using Illumina MiSeq platform. All treatments were well ensiled, and L. amylovorus improved aerobic stability. During aerobic exposure, Pichia kudriavzevii was detected with increased relative abundance in all treatments and more relative abundant in LP. Pichia fermentans was more relative abundant in control. Higher relative abundance of Pichia anomala was detected in deteriorating LP. The relative abundance of Pichia ohmeri increased during later aerobic exposure in the control and LA, with a significant increase in the count of yeast population. Despite Cryptococcus was detected more relative abundant during early stage of aerobic exposure, the yeast population was below the detection limit. Aerobic deterioration was characterized by an increase in operational taxonomic units of Pichia. High relative abundance of P. anomala and P. kudriavzevii made aerobic deterioration easier. Inhibition of P. fermentans might be an effective strategy for improving the aerobic stability to some instance.
Topics: Aerobiosis; Air; Bioreactors; Cryptococcus; Diet; Fermentation; Food Microbiology; Food Quality; High-Throughput Nucleotide Sequencing; Ipomoea batatas; Lactobacillus acidophilus; Lactobacillus plantarum; Pichia; Silage
PubMed: 32484290
DOI: 10.1111/asj.13397 -
Yeast (Chichester, England) Sep 2020In the present study, a total of eight sourdough samples were collected from three different bakeries at two different times in Turkey. Also, laboratory-scale sourdough...
In the present study, a total of eight sourdough samples were collected from three different bakeries at two different times in Turkey. Also, laboratory-scale sourdough production was conducted by daily back-slopping for 7 days. Microbiological and chemical properties of the sourdoughs were investigated. Yeast species in the sourdoughs were identified by subjecting all presumptive yeast cultures to internal transcribed spacer region amplification of the 5.8S rRNA gene, restriction fragment length polymorphism analysis using Hae III, Hha I, and Hinf I endonucleases, and sequence analysis of the D1/D2 domain of the 26S rDNA gene. A total of seven profiles were determined according to the restriction fragments. Totally, 148 yeast isolates were identified at the species level (≥400 bp, 99% identity) as Saccharomyces cerevisiae (106), Kazachstania bulderi (11), Pichia fermentans (nine), Pichia membranifaciens (eight), Kazachstania servazzii (seven), Kazachstania unispora (four), and Hanseniaspora valbyensis (three). Although collected sourdoughs were produced without using baker's yeast, S. cerevisiae was the most frequently isolated yeast species. This can be related to the contamination of the bakery environment with commercial baker's yeast during the production of other bakery products. The pH and acidity levels of the collected sourdough samples ranged from 3.71 to 3.96 and 6.78 to 23.93 mL 0.1 N NaOH/10 g dough, respectively. Mean values of the content of maltose + sucrose, glucose, fructose, lactic acid, and acetic acid were 2.43, 1.57, 2.67, 7.30, and 1.40 g/kg, respectively. Due to the artisan and region-dependent handling of the sourdough, different biochemical patterns were observed among the collected samples.
Topics: Bread; Fermentation; Flour; Food Microbiology; Microbiota; Turkey; Yeasts
PubMed: 32445425
DOI: 10.1002/yea.3500 -
Cytotechnology Jun 2020Squamous cell carcinoma (SCC) is one of the most common malignant tumors of the oral cavity. Probiotics have often been considered as effective anti-tumoral candidates....
Squamous cell carcinoma (SCC) is one of the most common malignant tumors of the oral cavity. Probiotics have often been considered as effective anti-tumoral candidates. This study aimed to investigate the role of Pichia fermentans YSH secretion metabolites on the induction of apoptosis in SCC. Cytotoxicity, apoptotic effects, and visualization DNA damage were evaluated by MTT, flow cytometry, and DAPI staining assays, respectively. Real-time PCR was employed for evaluation of the mechanism of cellular apoptosis. P. fermentans YSH secretions (IC) showed cellular cytotoxicity in human tongue squamous carcinoma (HSC4, RRID:CVCL_1289) cells (85% apoptosis) similar to the cytotoxicity of cisplatin whereas only 21% apoptosis was observed in human epithelial normal (KDR, RRID:CVCL_9V14) cells. The prophylactic efficacy of reference yeast, which regarded as a reference, was not comparable to P. fermentans YSH illustrating strain-dependent properties of bioactivities on oral disease control and prevention. According to our result, the main cytotoxicity is related to apoptosis mechanisms induced by apoptosis genes inducing BAX and CASP. However, follow-up researches should be performed to recognize the compounds to be utilized as effective anticancer therapeutics.
PubMed: 32253629
DOI: 10.1007/s10616-020-00392-w -
The Science of the Total Environment Jun 2020Vultures have evolved adaptive mechanisms to prevent infections associated with their scavenging lifestyle. However, food-borne exposure to antimicrobial pharmaceuticals...
Vultures have evolved adaptive mechanisms to prevent infections associated with their scavenging lifestyle. However, food-borne exposure to antimicrobial pharmaceuticals can promote opportunistic infections with adverse outcomes. Here, we used multivariate and network analyses to increase understanding of the behavior of the yeast communities causing oral mycosis outbreaks recently reported in wild nestling cinereous (Aegypius monachus), griffon (Gyps fulvus) and Egyptian (Neophron percnopterus) vultures (CV, GV and EV, respectively) exposed to antibiotics from livestock farming. Common and unique yeast signatures (of Candida, Debaromyces, Diutina, Meyerozyma, Naganishia, Pichia, Rhodotorula, Trichosporon and Yarrowia species) associated with oral mycoses were identified in the three vulture species. Hierarchical clustering analysis (HCA) and principal component analysis (PCA) highlighted that oral lesions from CV and GV shared similar yeast signatures (of major causative pathogens of opportunistic mycoses, such as Candida albicans, Candida parapsilosis and Candida tropicalis), while EV had a distinct yeast signature (of uncommon pathogenic species, such as Candida dubliniensis, Candida zeylanoides, Pichia fermentans and Rhodotorula spp.). Synergistic interactions between yeast species from distinct fungal phyla were found in lesions from CV and GV, but not in EV. These formed co-occurrence subnetworks with partially or fully connected topology. This study reveals that the composition, assembly and co-occurrence patterns of the yeast communities causing oral mycoses differ between vulture species with distinct feeding habits and scavenging lifestyles. Yeast species widely pathogenic to humans and animals, and yeast co-occurrence relationships, are distinctive hallmarks of oral mycoses in CV and GV. These vulture species are more exposed to antibiotics from intensively medicated livestock carcasses provided in supplementary feeding stations and show higher incidence of thrush-like oral lesions than EV. These findings may be useful for development of new initiatives or changes in the conservation of these avian scavengers affected by anthropogenic activities.
Topics: Animals; Anti-Bacterial Agents; Birds; Egypt; Humans; Livestock; Yeasts
PubMed: 32224410
DOI: 10.1016/j.scitotenv.2020.138166 -
Letters in Applied Microbiology Jan 2020This study aims to describe the native microbiota of fermented spelt, taking into consideration both lactic acid bacteria (LAB) and yeasts, for which little data are...
This study aims to describe the native microbiota of fermented spelt, taking into consideration both lactic acid bacteria (LAB) and yeasts, for which little data are available. Five samples of commercial spelt flour were subjected to spontaneous fermentation to obtain a type I sourdough. A total of 186 LAB and 174 yeast isolates were selected at different refreshment steps and subjected to further analyses. Within LAB, coccal isolates constituted 78·5% of the total LAB, with the dominance of Pediococcus pentosaceus. Although documented before as a component, this is the first report of a spelt sourdough fermentation dominated by this homofermentative LAB, characterized by a high acidification rate, ability to utilize a wide range of carbon sources and to grow in high osmolarity conditions. Yeast communities resulted in four dominant species, Saccharomyces cerevisiae, Wickerhamomyces anomalus, Pichia fermentans and Clavispora lusitaniae. This study highlights for the first time the biodiversity and dynamics of yeast communities involved in sourdough fermentation of spelt. Compared to commercial baker's yeast, autochthonous W. anomalus, P. fermentans and S. cerevisiae isolates show a good performance, and their use could be an advantage for their acquired adaptation to the environment, providing stability to the fermentation process. SIGNIFICANCE AND IMPACT OF THE STUDY: Nowadays, there is a renewed interest in products based on spelt. This 'ancient grain' is a highly nutritional grain; however, its use is limited to bread-making processes, which are not standardized. The low baking and sensory quality of spelt can be overcome through fermentation processes. However, the autochthonous microbiota of spelt sourdough is poorly known. This study highlights the dynamics of microbial communities involved in sourdough fermentation of spelt and provides the basis for the selection of autochthonous cultures, with the aim of improving the nutritional potential of spelt and its rheology and bread-making properties.
Topics: Biodiversity; Bread; Fermentation; Flour; Food Microbiology; Lactobacillales; Microbial Consortia; Triticum; Yeasts
PubMed: 31642537
DOI: 10.1111/lam.13241