0000000000066889
AUTHOR
Federico Uruburu
Characterisation of four species of the genus Kluyveromyces by mitochondrial DNA restriction analysis
Summary In the present work, we determine the relationships at the within-species level among strains of Kluyveromyces dobzhanskii, K. lactis, K. marxianus, and K. thermotolerans, through the restriction analysis of their mtDNAs. The three first species showed a high level of intraspecific mtDNA divergence, this polymorphism is correlated to the varieties or species defined according to the original taxonomy of the genus, which is in concordance with that shown by other phenotypic or genotypic markers codified for by the nuclear genome. In these species, the analysis of the relationships among strains based on mtDNA restriction data agrees with previous classifications based on morphologica…
Growth and macromolecular content of the dimorphic fungus Aureobasidium pullulans and the effect of hydroxyurea and other inhibitors
The growth kinetics and the macromolecular content of the yeast and ethanol-induced hyphal forms of Aureobasidium pullulans were studied. During the morphological transition from yeasts to hyphae, both the protein and RNA content decreased significantly, the mycelial form containing only 76% of the amount of protein in the yeasts, and 38% of the RNA. The DNA was the only component tested whose level increased during the transition. Among several compounds inhibiting macromolecular synthesis, only hydroxyurea showed a remarkable effect on the morphology of A. pullulans, inducing the mycelial morphology. The macromolecular composition of hydroxyurea-treated cultures changed with time in a way…
Yeast Population Dynamics during the Fermentation and Biological Aging of Sherry Wines
ABSTRACTMolecular and physiological analyses were used to study the evolution of the yeast population, from alcoholic fermentation to biological aging in the process of “fino” sherry wine making. The four races of “flor”Saccharomyces cerevisiae (beticus, cheresiensis, montuliensis, androuxii) exhibited identical restriction patterns for the region spanning the internal transcribed spacers 1 and 2 (ITS-1 and ITS-2) and the 5.8S rRNA gene, but this pattern was different, from those exhibited by non-florS. cerevisiaestrains. This flor-specific pattern was detected only after wines were fortified, never during alcoholic fermentation, and all the strains isolated from the velum exhibited the typ…
Selection and molecular characterization of wine yeasts isolated from the ‘El Penedès’ area (Spain)
Abstract A study of the microbiota present during the wine fermentation of five grape varieties from the ‘El Penedes’ area (Spain) was carried out to select autochthonous yeast strains for industrial wine production. In this study we identified members of the genera Candida, Dekkera, Hanseniaspora, Kluyveromyces, Torulaspora, Zygosaccharomyces and Saccharomyces in wine fermentation microbiota. Strains of Saccharomyces cerevisiae, as responsible agents of the alcoholic fermentation, were considered for a selection protocol. In this work we applied different enological criteria for selection, but previously we have characterized and differentiated Saccharomyces isolates by molecular methods t…
Aurintricarboxylic acid as a nuclease inhibitor in fungal protoplasts
Aurintricarboxylic acid (ATA), a potent nuclease inhibitor, has been shown to prevent foreign DNA degradation in transformation of Penicillium chrysogenum and Saccharomyces cerevisiae. ATA may be useful not only in vitro but also in vivo.
Penicillium auxotrophic mutants can be detected by suing xanthene dyes
Auxotrophic mutants ofPenicillium spp. have been directly isolated after mutagenic treatment from agar plates containing Xanthene dyes. They grow as characteristic small colored colonies. Some strains were tested and they showed a differential response depending on the Xanthene dye used.
Protoplasts fromPodospora anserina: Isolation, purification, and transformation
Protoplasts fromPodospora anserina mycelium were produced using the commercially available enzyme Novozym 234. Different parameters involved in protoplast isolation were analyzed in order to establish optimal conditions, and protoplast production was notably increased. For the purification of protoplasts, several techniques based on both centrifugation and filtration were assayed, with filtration yielding the best results. Regeneration of protoplasts was studied on different media and osmostic stabilizers, and about 80% regeneration was obtained. The good physiological condition of the protoplasts produced with this method is demonstrated by the lack of cell wall and high regeneration rate …
Virulence and Molecular Typing of Vibrio harveyi Strains Isolated from Cultured Dentex, Gilthead Sea Bream and European Sea Bass
Vibrio harveyi was isolated from internal organs or ulcers of diseased and apparently healthy gilthead sea bream (Sparus aurata) and European sea bass (Dicentrarchus labrax) cultured in several fish farms located on the Spanish Mediterranean coast. The prevalence of the bacterium was significantly higher in European sea bass than in gilthead sea bream, and was closely related to the season in both fish species, occurring almost exclusively on warm months (June to November). After phenotypic characterization, a selection of forty five isolates from gilthead sea bream, sea bass, and several isolates previously obtained from common dentex (Dentex dentex) of the same area, were molecularly type…
Dynamics of Microbial Populations during Fermentation of Wines from the Utiel-Requena Region of Spain
The dynamics of fungi, yeasts, and lactic acid bacteria during fermentation of four musts were studied. Fungi disappeared quickly in the fermenting must. The lactic acid bacteria population diminished during alcoholic fermentation, then they increased and performed malolactic fermentation. Yeasts grew quickly, reaching maximum populations at different times depending on the vinification treatment.
Polyphasic identification of yeasts isolated from bark of cork oak during the manufacturing process of cork stoppers.
A two-step protocol was used for the identification of 52 yeasts isolated from bark of cork oak at initial stages of the manufacturing process of cork stoppers. The first step in the identification was the separation of the isolates into groups by their physiological properties and RFLPs of the ITS-5.8S rRNA gene. The second step was the sequencing of the D1/D2 domains of the 26S rRNA gene of selected isolates representing the different groups. The results revealed a predominance of basidiomycetous yeasts (11 species), while only two species represented the ascomycetous yeasts. Among the basidiomycetous yeasts, members representing the species Rhodosporidium kratochvilovae and Rhodotorula n…
Identification of yeasts by RFLP analysis of the 5.8S rRNA gene and the two ribosomal internal transcribed spacers
The identification and classification of yeasts have traditionally been based on morphological, physiological and biochemical traits. Various kits have been developed as rapid systems for yeast identification, but mostly for clinical diagnosis. In recent years, different molecular biology techniques have been developed for yeast identification, but there is no available database to identify a large number of species. In the present study, the restriction patterns generated from the region spanning the internal transcribed spacers (ITS1 and ITS2) and the 5.8S rRNA gene were used to identify a total of 132 yeast species belonging to 25 different genera, including teleomorphic and anamorphic a…
Degradation of vanillic acid and production of guaiacol by microorganisms isolated from cork samples
The presence of guaiacol in cork stoppers is responsible for some cases of cork taint causing unpleasant alterations to wine. We have performed a characterization of the cork-associated microbiota by isolating 55 different microorganisms: eight yeast, 14 filamentous fungi or molds, 13 actinomycetes and 20 non-filamentous bacteria. A screening for degradation of vanillic acid and guaiacol production showed that none of the filamentous fungi could achieve any of these processes. By contrast, five of the eight yeast strains isolated were able to degrade vanillic acid, although it was not converted to guaiacol. Guaiacol production was only detected in four bacterial strains: one isolate of Baci…
History and services of culture collections.
Microbial culture collections aim at collecting, maintaining and distributing microbial strains among microbiologists, and are considered to be a means to preserve microbial diversity ex situ. This article reviews the early history of culture collections, which were first set up in the late nineteenth century, with the introduction of pure culture techniques. It also describes the international connections between culture collections, which led to the foundation of the World Federation for Culture Collections (WFCC) and the International Congress of Culture Collections (ICCC). An overview of the Spanish Type Culture Collection (CECT) is included, as well as a description of the services tha…