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1.
J Sci Food Agric ; 100(3): 1164-1173, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31680258

RESUMO

BACKGROUND: This study was conducted to analyze the effects of endophytic Bacillus megaterium (BM 18-2) colonization on structure strengthening, microbial community, chemical composition and stabilization properties of Hybrid Pennisetum. RESULTS: The BM 18-2 had successfully colonized in the interior tissues in both leaf and stem of Hybrid Pennisetum. During ensiling, the levels of pH, acetic acid (AA), butyric acid (BA), propionic acid (PA), and the population of yeast and aerobic bacteria were significantly (P > 0.05) lower, while lactic acid bacteria (LAB) and lactic acid (LA) were significantly (P < 0.001) higher with the steps forward of ensiling in with BM 18-2 as compared to without BM 18-2 colonized of Hybrid Pennisetum. During the different ensiling days, at days 3, 6, 15, and 30, the genus Brevundimonas, Klebsiella, Lactococcus, Weissella, Enterobacter, Serratia, etc. population were significantly decreased, while genus Pediococcus acidilactici and Lactobacillus plantarum were significantly influenced in treated groups as compared to control. The genus Lactobacillus and Pediococcus were positively correlated with treatment groups. CONCLUSIONS: It is concluded that the endophytic bacteria strain BM 18-2 significantly promoted growth characteristics and biomass yield before ensiling and after ensiling inoculated with or without Lactobacillus plantarum could improve the distinct changes of the undesirable microbial diversity, chemical composition, and stabilization properties in with BM 18-2 as compared to without BM 18-2 colonized Hybrid Pennisetum. © 2019 Society of Chemical Industry.


Assuntos
Bacillus megaterium/crescimento & desenvolvimento , Endófitos/crescimento & desenvolvimento , Microbiota , Pennisetum/microbiologia , Ácido Acético/metabolismo , Bacillus megaterium/genética , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Ácido Butírico/metabolismo , Endófitos/genética , Ácido Láctico/metabolismo , Pennisetum/genética , Pennisetum/crescimento & desenvolvimento , Leveduras/classificação , Leveduras/genética , Leveduras/isolamento & purificação , Leveduras/metabolismo
2.
Food Microbiol ; 86: 103339, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703886

RESUMO

The study of microbial communities associated with spontaneous fermentation of agave juice for tequila production is required to develop starter cultures that improve both yield and quality of the final product. Quantification by HPLC of primary metabolites produced during the fermentations was determined. A polyphasic approach using plate count, isolation and identification of microorganisms, denaturing gradient gel electrophoresis and next generation sequencing was carried out to describe the diversity and dynamics of yeasts and bacteria during small-scale spontaneous fermentations of agave juice from two-year samplings. High heterogeneity in microbial populations and fermentation parameters were observed, with bacteria showing higher diversity than yeast. The core microorganisms identified were Saccharomyces cerevisiae and Lactobacillus fermentum. Practices in tequila production changed during the two-year period, which affected microbial community structure and the time to end fermentation. Bacterial growth and concomitant lactic acid production were associated with low ethanol production, thus bacteria could be defined as contaminants in tequila fermentation and efforts to control them should be implemented.


Assuntos
Bebidas Alcoólicas/microbiologia , Bactérias/metabolismo , Leveduras/isolamento & purificação , Agave/química , Agave/microbiologia , Bebidas Alcoólicas/análise , Bactérias/química , Bactérias/genética , Bactérias/isolamento & purificação , Biodiversidade , Etanol/metabolismo , Fermentação , Cinética , Lactobacillus fermentum/química , Lactobacillus fermentum/metabolismo , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/metabolismo , Leveduras/química , Leveduras/genética , Leveduras/metabolismo
3.
Lett Appl Microbiol ; 70(1): 48-54, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31642537

RESUMO

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.


Assuntos
Pão/microbiologia , Lactobacillales/metabolismo , Consórcios Microbianos , Triticum/microbiologia , Leveduras/metabolismo , Biodiversidade , Pão/análise , Fermentação , Farinha/microbiologia , Microbiologia de Alimentos , Lactobacillales/classificação , Lactobacillales/genética , Lactobacillales/isolamento & purificação , Triticum/metabolismo , Leveduras/classificação , Leveduras/genética , Leveduras/isolamento & purificação
4.
An Acad Bras Cienc ; 91(4): e20190052, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31800704

RESUMO

The biotechnological potential of yeasts associated to different habitats in Colombia has been poorly studied, especially the yeasts associated with different plant structures. Fruit pulps are interesting substrates mainly for the growth of yeast species, that can positively affect the productivity and quality of some bioeconomic species. Therefore, the objective of this study was to identify the dominant yeast species associated with mango and rose apple fruit pulps in Cali, Colombia. A total of 90 isolates were obtained, which were grouped considering their colony morphology. The D1/D2 domain of the large ribosomal RNA gene (LSU rRNA gene) or internal transcribed spacer (ITS) 1, ribosomal gene 5.8S and ITS 2 (ITS) regions of one to several representative isolates from each group was sequenced and compared with type strains for identification. The species Hanseniaspora thailandica, H. opuntiae and Clavispora lusitaniae were reported as shared by both fruits, specific for rose apple (H. uvarum, Pichia terricola, Rhodosporidiobolus ruineniae and Candida albicans), or for Mango (Meyerozyma caribbica, M. guilliermondii, C. natalensis, Aureobasidium pullulans, Pichia sp., Saturnispora diversa and C. jaroonii). Two morphotypes were not identified at the taxonomic level of species and were reported as candidates for new species, belonging to the genera Wickerhamomyces and Pichia.


Assuntos
DNA Fúngico/genética , Frutas/microbiologia , Mangifera/microbiologia , Syzygium/microbiologia , Leveduras/genética , Colômbia , Reação em Cadeia da Polimerase , Leveduras/classificação , Leveduras/isolamento & purificação
5.
Pol J Microbiol ; 68(4): 493-504, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31880893

RESUMO

Bird fecal matter is considered a potential source of pathogenic microbes such as yeast species that contaminate the environment. Therefore, it needs to be scrutinized to assess potential environmental health risks. The aim of this study was to investigate the diversity of the yeasts in pigeon fecal droppings, their antifungal susceptibility patterns, and virulence factors. We used culturing techniques to detect the yeasts in pigeon fecal droppings. The isolates were then characterized based on colony morphologies, microscopic examinations, and biochemical reactions. The molecular identification of all yeast isolates was performed by sequencing of the amplified ITS gene. Genes encoding virulence factors CAP1, CAP59, and PLB were also detected. Antifungal susceptibility patterns were examined by the disk diffusion method. A total of 46 yeast-like isolates were recovered, and they belonged to nine different genera, namely, Cryptococcus, Saccharomyces, Rhodotorula, Candida, Meyerozyma, Cyberlindnera, Rhodosporidium, Millerozyma, and Lodderomyces. The prevalence of two genera Cryptococcus and Rhodotorula was high. None of the yeast isolates exhibited any resistance to the antifungal drugs tested; however, all pathogenic Cryptococcus species were positive for virulence determinants like urease activity, growth at 37°C, melanin production, the PLB and CAP genes. This is the first report on the molecular diversity of yeast species, particularly, Cryptococcus species and their virulence attributes in pigeon fecal droppings in Saudi Arabia.Bird fecal matter is considered a potential source of pathogenic microbes such as yeast species that contaminate the environment. Therefore, it needs to be scrutinized to assess potential environmental health risks. The aim of this study was to investigate the diversity of the yeasts in pigeon fecal droppings, their antifungal susceptibility patterns, and virulence factors. We used culturing techniques to detect the yeasts in pigeon fecal droppings. The isolates were then characterized based on colony morphologies, microscopic examinations, and biochemical reactions. The molecular identification of all yeast isolates was performed by sequencing of the amplified ITS gene. Genes encoding virulence factors CAP1, CAP59, and PLB were also detected. Antifungal susceptibility patterns were examined by the disk diffusion method. A total of 46 yeast-like isolates were recovered, and they belonged to nine different genera, namely, Cryptococcus, Saccharomyces, Rhodotorula, Candida, Meyerozyma, Cyberlindnera, Rhodosporidium, Millerozyma, and Lodderomyces. The prevalence of two genera Cryptococcus and Rhodotorula was high. None of the yeast isolates exhibited any resistance to the antifungal drugs tested; however, all pathogenic Cryptococcus species were positive for virulence determinants like urease activity, growth at 37°C, melanin production, the PLB and CAP genes. This is the first report on the molecular diversity of yeast species, particularly, Cryptococcus species and their virulence attributes in pigeon fecal droppings in Saudi Arabia.


Assuntos
Columbidae/microbiologia , Fezes/microbiologia , Fatores de Virulência/metabolismo , Leveduras/efeitos dos fármacos , Leveduras/isolamento & purificação , Animais , Antifúngicos/farmacologia , Biodiversidade , Fluconazol/farmacologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Testes de Sensibilidade Microbiana , Arábia Saudita , Fatores de Virulência/genética , Leveduras/genética , Leveduras/metabolismo
6.
J Food Sci ; 84(10): 2944-2954, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31553057

RESUMO

The objective of this study was to isolate and identify the microorganisms, especially yeasts and molds, related to the improvement of beef quality during dry-aging of beef through microbiome analysis, and to examine the possibility of using them as starter culture strains to improve the efficiency of dry-aging beef production. Beef sirloins were dry-aged for 28 days using different wind speeds (0, 2.5, and 5 m/s) at 1 to 3 °C and 75% relative humidity, and microbial compositions were confirmed by microbiome analysis. Mold and yeast samples were plated on potato dextrose agar supplemented with 10% tartaric acid, and the isolated colonies were identified by DNA sequencing. The isolates were subjected to microbial characterization (morphological characterization, growth condition, and enzyme activity). Microbiome analysis showed that the dominant microorganisms were molds and yeasts identified as Pilaira anomala SMFM201611 and Debaryomyces hansenii SMFM201707. Pilaira anomala SMFM201611 and D. hansenii SMFM201707 were inoculated into 24 sirloins of the lowest grade. All samples were dry-aged for 0, 14, 21, and 28 days and analyzed for microbial growth, pH, shear force, ultrastructure, and flavor compounds (free amino acids and free fatty acids). Inoculation with P. anomala SMFM201611 and D. hansenii SMFM201707 improved tenderness and cause the breakdown of myofibrils by proteolysis. Both microorganisms also produced free amino acids and fatty acids through proteolytic and lipolytic activities. These results indicate that P. anomala SMFM201611 and D. hansenii SMFM201707 isolated and identified from dry-aged beef can improve the quality of low-grade beef during dry-aging. PRACTICAL APPLICATION: During dry-aging, mold and yeast improve the quality of dry-aged beef. Pilaira anomala SMFM201611 and Debaryomyces hansenii SMFM201707 isolated from dry-aged beef can improve tenderness by breaking down myofibrils. Both microorganisms improve flavor by producing free fatty acids and amino acids, and the taste and aroma characteristics of low-grade beef may be improved during the dry-aging process.


Assuntos
Fungos/isolamento & purificação , Microbiota , Carne Vermelha/microbiologia , Leveduras/isolamento & purificação , Animais , Bovinos , Aromatizantes/análise , Microbiologia de Alimentos , Fungos/classificação , Fungos/genética , Fungos/crescimento & desenvolvimento , Humanos , Produtos da Carne/análise , Odorantes/análise , Melhoria de Qualidade , Carne Vermelha/análise , Análise de Sequência de DNA , Paladar , Leveduras/classificação , Leveduras/genética , Leveduras/crescimento & desenvolvimento
7.
Int J Food Microbiol ; 308: 108287, 2019 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-31437693

RESUMO

This study investigated the use of seed extract from Moringa oleifera Lamark (MO) for both clarifying the sugarcane juice and removing fermentation contaminants that originated during the 24 h storage of the freshly cut stalks. The addition of the MO seed extract during the juice clarification step decreased the total microbial population by 41.66% compared to the other treatments. The non-stored raw material had less lactic acid bacteria and yeasts counts in the fermentation process, resulting in 8.8% lower glycerol content compared to the stored raw material. The concentrations of congeners in both raw materials decreased by 5.27% after liming and by 10% after using the natural extract with flocculation activity. It can be concluded that the clarification process combined with the use of the seed extract from Moringa oleifera Lamarck can potentially control microbial contaminating during fermentation and increase the alcohol content in the cachaça.


Assuntos
Bactérias/isolamento & purificação , Moringa oleifera/química , Extratos Vegetais/farmacologia , Leveduras/isolamento & purificação , Fermentação/efeitos dos fármacos , Floculação/efeitos dos fármacos , Sementes/química
8.
Int J Syst Evol Microbiol ; 69(11): 3385-3391, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31368884

RESUMO

During a survey of yeast populations associated with grape and apple musts used for wine and cider fermentation, respectively, six pink-coloured ballistoconidia-forming yeasts belonging to the order Sporidiobolales (Basidiomycota) were isolated. Phylogenetic analysis inferred using sequences of the internal transcribed spacer (ITS), the D1/D2 domain of the large subunit rRNA gene, the small subunit (SSU) rRNA gene and DNA-directed RNA polymerase II subunit (RPB2) indicated that the six isolates were separated in two novel species. One of the new species, Sporobolomyces agrorum sp. nov., isolated from grape must, had Sporobolomyces roseus and Sporobolomyces metaroseus as its closest relatives, but showed four/two and 16 nucleotide substitutions in the D1/D2 and ITS regions, respectively, to these two species. The other novel species, Sporobolomyces sucorum sp. nov., was found in apple must and was closely related to Sporobolomyces pararoseus and Sporobolomyces patagonicus, but showed two/three and five substitutions in those two regions for its closest relatives. We detected additional representatives of this species, most of them isolated from grapes whose sequences were already available on public databases. A sexual stage could not be observed for the novel species.


Assuntos
Basidiomycota/classificação , Malus/microbiologia , Filogenia , Vitis/microbiologia , Basidiomycota/isolamento & purificação , DNA Fúngico/genética , DNA Espaçador Ribossômico/genética , Itália , Técnicas de Tipagem Micológica , Análise de Sequência de DNA , Esporos Fúngicos , Leveduras/classificação , Leveduras/isolamento & purificação
9.
World J Microbiol Biotechnol ; 35(7): 108, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31267227

RESUMO

A total of 191 yeasts were isolated from 197 samples collected from eight estuarine mangrove forests along four different coastlines of Thailand (Andaman Sea and the East, North and West coasts of the Gulf of Thailand). Of these, 178 isolates were identified as 32 species in 16 genera of Ascomycota, 12 species in nine genera of Basidiomycota, and 13 isolates as potential new species, respectively. Mangroves located along the Andaman Sea coastline had a higher yeast diversity at the species and genera levels than those along the Gulf of Thailand. Kluyveromyces siamensis was the most frequently isolated species, whilst Candida tropicalis was the only species isolated at all eight sites. Screening isolated yeast strains belonging to genera previously reported as oleaginous yeast plus the 13 potential new species, revealed two oleaginous strains, Rhodotorula sphaerocarpa 11-14.4 and Saitozyma podzolica 11-11.3.1. Both of these strains were isolated from the same mangrove forest on the Andaman Sea coastline. They could accumulate lipid when suspended in glucose solution without any supplementation, while the fatty acid composition and oil profile of Rh. sphaerocarpa 11-14.4 and Sait. podzolica 11-11.3.1 were similar to vegetable oil and cocoa butter, respectively.


Assuntos
Filogenia , Áreas Alagadas , Leveduras/classificação , Leveduras/isolamento & purificação , Ascomicetos/química , Ascomicetos/classificação , Ascomicetos/isolamento & purificação , Basidiomycota/química , Basidiomycota/classificação , Basidiomycota/isolamento & purificação , Biodiversidade , Biocombustíveis , DNA Fúngico/análise , DNA Fúngico/isolamento & purificação , Gorduras na Dieta , Ácidos Graxos/análise , Glucose/metabolismo , Metabolismo dos Lipídeos , Lipídeos/análise , Tipagem Molecular , Óleos Vegetais , RNA Ribossômico/genética , Análise de Sequência , Tailândia , Leveduras/química , Leveduras/genética
10.
J Mycol Med ; 29(3): 265-272, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31285126

RESUMO

Onychomycosis or fungal nail infection is one of the most common fungal infections. Nearly 50% of all nail disorders are caused by fungi. This systematic review and meta-analysis was conducted to determine the prevalence of onychomycosis across Iran. We searched English and Persian databases for studies reporting the epidemiologic features of onychomycosis in Iranian people from January 2000 to December 2018. Literature search revealed 307 studies, of which 24 studies met the eligibility criteria. In order to identifying the existence of publication bias among studies, funnel plots were used. The results of the meta-analysis were visualized as a forest plot representing the prevalence estimates of each study. Heterogeneity was also analyzed using the I2, Chi2, and Tau2 statistics. A high level of I2 and Chi2 was obtained among studies, which provides evidence of notable heterogeneity between studies. The results of current study revealed that the highest prevalence of onychomycosis was related to Mazandaran and Tehran provinces, respectively. As in the literature hypothesized shift in etiologic agents from yeasts to dermatophytes or molds could not be confirmed. Females were affected more frequently than males and in both sexes the highest incidence of infection occurrence was at the ages of >50 years. It seems the highest prevalence of onychomycosis in Mazandaran and Tehran provinces is due to the concentration of specialist doctors and research centers in these two provinces compared with others which leads to more detection and more care of the disease. Therefore, further educational strategies in order to accurate diagnosis in other provinces is necessary to reduce the risk of onychomycosis in Iran.


Assuntos
Arthrodermataceae/isolamento & purificação , Dermatomicoses/epidemiologia , Onicomicose/epidemiologia , Leveduras/isolamento & purificação , Fatores Etários , Dermatomicoses/microbiologia , Feminino , Geografia , Humanos , Irã (Geográfico)/epidemiologia , Masculino , Onicomicose/microbiologia , Prevalência , Fatores de Risco , Fatores Sexuais
11.
Food Sci Technol Int ; 25(8): 671-679, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31272221

RESUMO

Spoilage caused by yeasts is a constant, widespread problem in the beverage industry that can result in major economic losses. Fruit juices provide an environment that allows the proliferation of yeast. Some factories in South Africa are not equipped with laboratory facilities to identify spoilage yeasts and outsourcing becomes a prolonged process which obstructs corrective action planning. This study aimed to establish yeast diversity and apply a rapid method for preliminary identification of spoilage yeasts associated with a small-scale fruit juice bottling factory. Yeast population in the factory was determined by isolation from the production environment, process equipment and spoiled products. PCR-RFLP analysis targeting the 5.8S-ITS region and D1/D2 sequencing was used for identification. A total of 207 yeasts belonging to 10 different genera (Candida, Lodderomyces, Wickerhamomyces, Yarrowia, Zygosaccharomyces, Zygoascus, Cryptococcus, Filobasidium, Rhodotorula/Cystobasidium and Trichosporon) were isolated and identified from the production environment and processing equipment. Candida intermedia, C. parapsilosis and Lodderomyces elongisporus were widely distributed in the factory. Zygosaccharomyces bailii, Z. bisporus, Zygoascus hellenicus and Saccharomyces cerevisiae were isolated from the spoiled products. The data provided a yeast control panel that was used successfully to identify unknown yeasts in spoiled products from this factory using polymerase chain reaction-restriction length polymorphism (PCR-RFLP) comparative analysis.


Assuntos
Contaminação de Alimentos/análise , Sucos de Frutas e Vegetais/microbiologia , Reação em Cadeia da Polimerase/métodos , Polimorfismo de Fragmento de Restrição , Leveduras/classificação , Leveduras/isolamento & purificação , Biodiversidade , DNA Fúngico , Manipulação de Alimentos , Técnicas de Tipagem Micológica , RNA Ribossômico/análise , RNA Ribossômico/genética , RNA Ribossômico 5,8S/análise , RNA Ribossômico 5,8S/genética , Análise de Sequência , Leveduras/genética , Leveduras/crescimento & desenvolvimento
12.
Int J Food Microbiol ; 306: 108263, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31306941

RESUMO

Ishizuchi-kurocha is a Japanese traditional fermented tea that is produced by primary aerobic and secondary fermentation steps. The secondary fermentation step of Ishizuchi-kurocha is mainly mediated through lactic acid bacteria. Here, we performed quantitative analyses of the culturable fungal communities at each step and identified several morphologically representative fungal isolates. While filamentous fungi (median, 3.2 × 107 CFU/g sample) and yeasts (median, 3.7 × 107 CFU/g) were both detected after the primary fermentation step, only yeasts (median, 1.6 × 107 CFU/g) were detected in the end of the secondary fermentation step, suggesting that the fungal community in tea leaves are dramatically changed between the two steps. Pichia kudriavzevii and Pichia manshurica, the prevalent fungal species at the end of the secondary fermentation step, grew well in exudate from the secondary fermentation step. P. kudriavzevii also grew well in media containing d- or l-lactate as the sole carbon source. The growth of the disruptant of cyb2A encoding a cytochrome b2 lactate dehydrogenase in P. kudriavzevii was severely impaired on medium supplemented with l-lactate, but not d-lactate, suggesting that Cyb2Ap plays a crucial role in the use of l-lactate, and P. kudriavzevii efficiently uses both l- and d-lactate as carbon sources. Thus, lactate assimilation seems to be a key phenotype to become a prevalent species in the secondary fermentation step, and Cyb2Ap has a pivotal role in l-lactate metabolism in P. kudriavzevii. Further understanding and engineering of P. kudriavzevii and P. manshurica will contribute to the control of lactic acid bacteria fermentation during the fermented tea production and also to other industrial uses.


Assuntos
/microbiologia , L-Lactato Desidrogenase (Citocromo)/genética , Ácido Láctico/metabolismo , Pichia/genética , Pichia/metabolismo , Reatores Biológicos , Candida/isolamento & purificação , Fermentação , Pichia/isolamento & purificação , Leveduras/isolamento & purificação
13.
PLoS One ; 14(6): e0217385, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31220090

RESUMO

Yeast species that colonize the surface of grape berries at harvest time play an important role during the winemaking process. In this study, the use of culturable microbial techniques permitted a quantitative and qualitative inventory of the different yeast species present on the grape berry surfaces of Montepulciano and Verdicchio varieties when treated with conventional and organic fungicides. The results show that the most widespread yeast species at harvest time were Aureobasidium pullulans and Hanseniaspora uvarum, which are considered normal resident species and independent of the grape varieties and treatments applied. Specific differences when comparing the grape varieties were observed in species and were detected at a lower frequency; Pichia spp. were prevalent in Verdicchio, whereas Lachancea thermotolerans and Zygoascus meyerae were found in Montepulciano. In both vineyards, the farming treatments improved the competitiveness of A. pullulans, which was probably due to its reduced susceptibility to treatments that improved the competition toward other fungi. In contrast, the fermenting yeast H. uvarum was negatively affected by fungicide treatments and showed a reduced presence if compared with untreated grapes. Organic treatments directly impacted the occurrence of Issachenkia terricola in Montepulciano grapes and Debaryomyces hansenii and Pichia membranifaciens in Verdicchio. Conversely, a negative effect of organic treatments was found toward Metschnikowia pulcherrima and Starmerella bacillaris. Overall, the data suggest that the yeast community colonizing the grape berry surface was influenced by both grape variety and farming treatments, which characterized the yeast biota of spontaneous must fermentation.


Assuntos
Microbiota , Vitis/microbiologia , Leveduras , Fazendas , Leveduras/classificação , Leveduras/crescimento & desenvolvimento , Leveduras/isolamento & purificação
14.
J Appl Microbiol ; 127(3): 845-855, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31211890

RESUMO

AIMS: The aim was to isolate, identify and characterize yeasts present in rumen fluid and to select strains showing potential as probiotics. METHODS AND RESULTS: Rumen fluid was sampled from 4 herds of dairy and beef cattle and 77 yeast isolates were identified. Initial screening was based on the capacity to maintain viability in a medium with different ruminal conditions. A second screening in fresh rumen fluid to assess the growth of inoculated yeasts and evaluate in vitro neutral detergent fibre digestibility (NDF-D), pH and acid accumulation was conducted. The yeast population ranged from 3·84 to 6·76 log10 CFU per ml. The main species of yeast found were Pichia kudriavzevii, Candida rugosa, C. pararugosa, C. ethanolica and Magnusiomyces capitatus. Strains CCMA 933 (C. rugosa) and CCMA 970 (C. pararugosa) showed greater ability to survive in ruminal fluid and stimulated the production of acids. Isolate CCMA 967 (C. ethanolica) survived and improved the NDF-D. CONCLUSION: Pichia kudriavzevii was the dominant yeast found in the cattle herds. Strains CCMA 933, CCMA 970 and CCMA 967 showed properties that could be useful as potential probiotics for cattle. SIGNIFICANCE AND IMPACT OF THE STUDY: This study was the first to select yeasts from the rumen fluid, with the potential to be used as probiotic, based on the ruminal conditions.


Assuntos
Probióticos/isolamento & purificação , Rúmen/microbiologia , Leveduras/classificação , Ração Animal , Animais , Bovinos , Feminino , Fermentação , Rúmen/metabolismo , Leveduras/isolamento & purificação , Leveduras/fisiologia
15.
Arch Microbiol ; 201(8): 1147-1149, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31147748

RESUMO

Non-albicans Candida species have acquired relevance in the last decades as a cause of serious disease. The virulence factors and antifungal susceptibility of these rare pathogens remain largely unrecognized. We examined a total of 50 yeast isolates corresponding to 11 different infrequently isolated yeast species for their in vitro enzymatic profile and susceptibility pattern as first-line antifungals. We found aspartyl protease activity for 100% of the isolates tested as well as variable DNAse, hemolysin, phospholipase and esterase activities. All strains had low MICs for amphotericin B and showed a variable response to fluconazole (0.125-32 µg/mL) and the echinocandins tested (0.25-> 8 µg/mL).


Assuntos
Anfotericina B/farmacologia , Antifúngicos/farmacologia , Candida/efeitos dos fármacos , Candida/genética , Equinocandinas/farmacologia , Fluconazol/farmacologia , Ácido Aspártico Proteases/genética , Candida/classificação , Candida/isolamento & purificação , Desoxirribonucleases/genética , Esterases/genética , Proteínas Hemolisinas/genética , Humanos , Testes de Sensibilidade Microbiana , Fosfolipases/genética , Fatores de Virulência , Leveduras/classificação , Leveduras/efeitos dos fármacos , Leveduras/isolamento & purificação
16.
Int J Food Microbiol ; 304: 75-88, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31174038

RESUMO

Fermented cereal doughs constitute a predominant part of West African diets. The environment of fermented doughs can be hostile for microbial survival due to high levels of microbial metabolites such as weak carboxylic organic acids and ethanol. In order to get a better understanding of the intrinsic factors affecting the microbial successions of yeasts during dough fermentation, survival and physiological responses of the yeasts associated with West African fermented cereal doughs were investigated at exposure to relevant concentrations of microbial inhibitory compounds. Three strains each of the predominant species, i.e. Saccharomyces cerevisiae, Kluyveromyces marxianus, Pichia kudriavzevii as well as the opportunistic pathogen Candida glabrata were studied. The strains were exposed to individual stress factors of cereal doughs, i.e. (i) pH 3.4, (ii) 3% (v/v) ethanol (EtOHpH3.4), (iii) 285 mM lactic acid (LApH3.4) and (iv) 150 mM acetic acid (AApH3.4) as well as to combinations of these stress factors, i.e. (v) (LA + AA)pH 3.4 and (vi) (LA + AA+EtOH)pH 3.4. Growth and single cell viability were studied by flow cytometry using combined SYTO 13 and propidium iodide (PI) staining. Intracellular pH (pHi), plasma membrane integrity and micro-colony development of stressed cells were studied by fluorescence microscopy using PI and carboxyfluorescein diacetate succinimidyl ester (CFDA-se). Viability of the yeast strains was not affected by pH 3.4 and 3% (v/v) ethanol (EtOHpH3.4). 285 mM lactic acid (LApH3.4) reduced the specific growth rate (µmax) from 0.27-0.41 h-1 to 0.11-0.26 h-1 and the viability from 100% to 2.6-41.7% at 72 h of exposure in most yeast strains, except for two strains of C. glabrata. 150 mM acetic acid (AApH3.4) as well as the combinations (LA + AA)pH 3.4 and (LA + AA+EtOH)pH 3.4 reduced µmax to 0.0 h-1 and induced significant cell death for all the yeast strains. Exposed to (LA + AA+EtOH)pH 3.4, the most resistant yeast strains belonged to S. cerevisiae followed by P. kudriavzevii, whereas C. glabrata and K. marxianus were more sensitive. Strain variations were observed within all four species. When transferred to non-stress conditions, i.e. MYGP, pH 5.6, after exposure to (LA + AA+EtOH)pH 3.4 for 6 h, 45% of the single cells of the most resistant S. cerevisiae strain kept their plasma membrane integrity, recovered their pHi to near physiological range (pHi = 6.1-7.4) and resumed proliferation after 3-24 h of lag phase. The results obtained are valuable in order to change processing conditions of the dough to favor the survival of preferable yeast species, i.e. S. cerevisiae and K. marxianus and inhibit opportunistic pathogen yeast species as C. glabrata.


Assuntos
Candida/efeitos dos fármacos , Grão Comestível/microbiologia , Kluyveromyces/efeitos dos fármacos , Viabilidade Microbiana/efeitos dos fármacos , Pichia/efeitos dos fármacos , Saccharomyces cerevisiae/efeitos dos fármacos , Ácido Acético/farmacologia , Reatores Biológicos , Candida/crescimento & desenvolvimento , Candida/isolamento & purificação , Etanol/farmacologia , Fermentação , Kluyveromyces/crescimento & desenvolvimento , Kluyveromyces/isolamento & purificação , Ácido Láctico/farmacologia , Pichia/crescimento & desenvolvimento , Pichia/isolamento & purificação , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/isolamento & purificação , Fermento Seco , Leveduras/isolamento & purificação
17.
World J Microbiol Biotechnol ; 35(7): 100, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31222403

RESUMO

The spontaneously fermented curdled milk product from Burkina Faso, lait caillé is prepared by traditional processing from raw unpasteurised milk. The fermentation lasts 1-3 days. This study aims to identify the predominant microbiota involved in lait caillé fermentation from cow milk. A survey on lait caillé end-products from local markets showed pH ranges of 3.5 to 4.2. Counts of total lactic acid bacteria (LAB) were 7.8 ± 0.06 to 10.0 ± 0.03 log CFU/g and yeast counts were 5.3 ± 0.06 to 8.7 ± 0.01 log CFU/g, together with considerate amounts of Enterobacteriaceae < 3.00 to 8.4 ± 0.14 log CFU/g. Sampling throughout the entire fermentation of lait caillé was performed at a traditional house-hold production site. A drop in pH from 6.7 ± 0.01 at 0 h to 4.3 ± 0.08 in the end-product (59 h) was found. Total LAB counts increased to 8.6 ± 0.02 log CFU/g in the end-product, while yeast and Enterobacteriaceae counts reached 6.4 ± 0.11 and 6.7 ± 0.00 log CFU/g, respectively. LAB and yeasts isolated during the fermentation were clustered by (GTG)5 repetitive-PCR fingerprinting followed by 16S and 26S rRNA gene sequencing, respectively. Microbial successions were observed with Leuconostoc mesenteroides being the predominant LAB followed by Pediococcus pentosaceus and Weissella paramesenteroides at the onset, while Lactococcus lactis and Enterococcus spp. where the predominant LAB after 7 h of fermentation. During the first 18 h Candida parapsilosis was the dominant yeast species, while from 35 h to the end-product, Saccharomyces cerevisiae predominated. The microbial safety risk pointed out in this study, showed the need for implementation of good manufacturing practices including pasteurisation and use of well-defined starter cultures.


Assuntos
Produtos Fermentados do Leite/microbiologia , Microbiota/genética , Burkina Faso , Contagem de Colônia Microbiana , Enterobacteriaceae/genética , Enterobacteriaceae/isolamento & purificação , Enterococcus/genética , Enterococcus/isolamento & purificação , Fermentação , Manipulação de Alimentos , Microbiologia de Alimentos , Concentração de Íons de Hidrogênio , Lactobacillales/genética , Lactobacillales/isolamento & purificação , Lactococcus lactis/genética , Lactococcus lactis/isolamento & purificação , RNA Ribossômico/genética , RNA Ribossômico/isolamento & purificação , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/isolamento & purificação , Análise de Sequência de RNA , Leveduras/genética , Leveduras/isolamento & purificação
18.
Curr Microbiol ; 76(7): 909-916, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31119361

RESUMO

The aim of the present study was to assess the transcription of the plnE/F, plnN, plnG, plnD and plnI genes during lactic acid fermentation of radish (Raphanus sativus) roots by Lactobacillus plantarum strain LQC 740 at 20 and 30 °C. At both temperatures, this strain dominated the fermentation process, as indicated by (GTG)5 analysis. A total of five pln genes were detected in the genome of this strain, namely plnE/F, plnN, plnG, plnD and plnI. Regarding plantaricin genes expression, no regulation was observed in the majority of the samples at both temperatures, therefore, the transcription of the pln genes was not affected by the experimental conditions, i.e. radish fermentation vs. growth in MRS broth. Although transcription of the pln genes was similar between the two conditions, bacteriocin activity was different. The maximum plantaricin activity was 87.5 AU/mL during radish fermentation and 700 AU/mL during growth in MRS broth. Thus, no apparent correlation between bacteriocin activity and transcription level of the five pln genes could be established.


Assuntos
Bacteriocinas/genética , Regulação da Expressão Gênica , Lactobacillus plantarum/metabolismo , Raphanus/microbiologia , Bactérias/classificação , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Bacteriocinas/metabolismo , Fermentação , Concentração de Íons de Hidrogênio , Lactobacillus plantarum/genética , Lactobacillus plantarum/crescimento & desenvolvimento , Microbiota/genética , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Raphanus/metabolismo , Leveduras/classificação , Leveduras/genética , Leveduras/crescimento & desenvolvimento , Leveduras/isolamento & purificação
19.
mBio ; 10(2)2019 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-31040238

RESUMO

Ancient fermented food has been studied based on recipes, residue analysis, and ancient-DNA techniques and reconstructed using modern domesticated yeast. Here, we present a novel approach based on our hypothesis that enriched yeast populations in fermented beverages could have become the dominant species in storage vessels and their descendants could be isolated and studied today. We developed a pipeline of yeast isolation from clay vessels and screened for yeast cells in beverage-related and non-beverage-related ancient vessels and sediments from several archaeological sites. We found that yeast cells could be successfully isolated specifically from clay containers of fermented beverages. The findings that genotypically the isolated yeasts are similar to those found in traditional African beverages and phenotypically they grow similar to modern beer-producing yeast strongly suggest that they are descendants of the original fermenting yeast. These results demonstrate that modern microorganisms can serve as a new tool in bio-archaeology research.IMPORTANCE So far, most of the study of ancient organisms has been based mainly on the analysis of ancient DNA. Here we show that it is possible to isolate and study microorganisms-yeast in this case-from ancient pottery vessels used for fermentation. We demonstrate that it is highly likely that these cells are descendants of the original yeast strains that participated in the fermentation process and were absorbed into the clay matrix of the pottery vessels. Moreover, we characterized the isolated yeast strains, their genomes, and the beer they produced. These results open new and exciting avenues in the study of domesticated microorganisms and contribute significantly to the fields of bio- and experimental archaeology that aim to reconstruct ancient artifacts and products.


Assuntos
Arqueologia/métodos , Fósseis/microbiologia , Sedimentos Geológicos/microbiologia , Técnicas Microbiológicas/métodos , Leveduras/isolamento & purificação , Genótipo
20.
Lett Appl Microbiol ; 68(6): 580-588, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30929264

RESUMO

The use of commercial yeast strains is a common practice in winemaking leading to a predictable quality in wine production, avoiding stuck or sluggish fermentations. However, the use of commercial yeasts leads to a consequent reduction in autochthonous microbial diversity. In this study, 1047 isolates from three Spanish appellations of origin were checked for fingerprinting on interdelta polymorphisms and the strain composition and diversity analysed using an extensible open-source platform for processing and analysis of an in-house polymorphism database developed for this study. Ancient vineyards managed with organic practices showed intermediate to low levels of strains diversity indicating the existence of stable populations of Saccharomyces cerevisiae strains. A drastic reduction in the number of different S. cerevisiae strains was observed in vineyards with cellars using a selected autochthonous S. cerevisiae strain for winemaking. Contrary, the use of allochthonous commercial strains in wineries did not seem to affect the native S. cerevisiae strain composition and diversity. SIGNIFICANCE AND IMPACT OF THE STUDY: The aim of this study was to compare different viticulture and oenological practices to determine their influence on the composition and diversity of Saccharomyces cerevisiae strains in wine fermentations. The study shows that the use of autochthonous strains of S. cerevisiae as starters for wine fermentation could have an important incidence on S. cerevisiae strains diversity in surrounding vineyards. The use of autochthonous strains of S. cerevisiae reduced the detected number of S. cerevisiae strains, a fact that was not observed when allochthonous commercial strains were used. Furthermore, vineyards managed with organic practices showed intermediate to low levels of S. cerevisiae strain diversity, whereas conventional practices showed higher levels.


Assuntos
Biodiversidade , Saccharomyces cerevisiae/classificação , Saccharomyces cerevisiae/isolamento & purificação , Vitis/microbiologia , Vinho/microbiologia , Reatores Biológicos , Fazendas , Fermentação , Polimorfismo Genético/genética , Saccharomyces cerevisiae/genética , Leveduras/isolamento & purificação
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