1,721,039 research outputs found
A genomic approach to analyze the cold adaptation of yeasts isolated from Italian Alps
No full textMicroorganisms including yeasts are responsible for mineralization of organic matter in cold regions, and their characterization is critical to elucidate the ecology of such environments on Earth. Strategies developed by yeasts to survive in cold environments have been increasingly studied in the last years and applied to different biotechnological applications, but their knowledge is still limited. Microbial adaptations to cold include the synthesis of cryoprotective compounds, as well as the presence of a high number of genes encoding the synthesis of proteins/enzymes characterized by a reduced proline content and highly flexible and large catalytic active sites. This study is a comparative genomic study on the adaptations of yeasts isolated from the Italian Alps, considering their growth kinetics. The optimal temperature for growth (OTG), growth rate (Gr), and draft genome sizes considerably varied (OTG, 10°C–20°C; Gr, 0.071–0.0726; genomes, 20.7–21.5 Mpb; %GC, 50.9–61.5). A direct relationship was observed between calculated protein flexibilities and OTG, but not for Gr. Putative genes encoding for cold stress response were found, as well as high numbers of genes encoding for general, oxidative, and osmotic stresses. The cold response genes found in the studied yeasts play roles in cell membrane adaptation, compatible solute accumulation, RNA structure changes, and protein folding, i.e., dihydrolipoamide dehydrogenase, glycogen synthase, omega-6 fatty acid, stearoyl-CoA desaturase, ATP-dependent RNA helicase, and elongation of very-long-chain fatty acids. A redundancy for several putative genes was found, higher for P-loop containing nucleoside triphosphate hydrolase, alpha/beta hydrolase, armadillo repeat-containing proteins, and the major facilitator superfamily protein. Hundreds of thousands of small open reading frames (SmORFs) were found in all studied yeasts, especially in Phenoliferia glacialis. Gene clusters encoding for the synthesis of secondary metabolites such as terpene, non-ribosomal peptide, and type III polyketide were predicted in four, three, and two studied yeasts, respectively
Application of anhydrobiosis and dehydration of yeasts for non-conventional biotechnological goals
No full textDehydration of yeast cells causes them to enter a state of anhydrobiosis in which their metabolism is temporarily and reversibly suspended. This unique state among organisms is currently used in the production of active dry yeasts, mainly used in baking and winemaking. In recent decades non-conventional applications of yeast dehydration have been proposed for various modern biotechnologies. This mini-review briefly summarises current information on the application of dry yeasts in traditional and innovative fields. It has been shown that dry yeast preparations can be used for the efficient protection, purification and bioremediation of the environment from heavy metals. The high sorption activity of dehydrated yeasts can be used as an interesting tool in winemaking due to their effects on quality and taste. Dry yeasts are also used in agricultural animal feed. Another interesting application of yeast dehydration is as an additional stage in new methods for the stable immobilisation of microorganisms, especially in cases when biotechnologically important strains have no affinity with the carrier. Such immobilisation methods also provide a new approach for the successful conservation of yeast strains that are very sensitive to dehydration. In addition, the application of dehydration procedures opens up new possibilities for the use of yeast as a model system. Separate sections of this review also discuss possible uses of dry yeasts in biocontrol, bioprotection and biotransformations, in analytical methods as well as in some other areas
Psychrophilic yeasts from worldwide glacial habitats: diversity, adaptation strategies and biotechnological potential
No full textGlacial habitats (cryosphere) include some of the largest unexplored and
extreme biospheres on Earth. These habitats harbor a wide diversity of psychrophilic
prokaryotic and eukaryotic microorganisms. These highly specialized
microorganisms have developed adaptation strategies to overcome the direct
and indirect life-endangering influence of low temperatures. For many years
Antarctica has been the geographic area preferred by microbiologists for studying
the diversity of psychrophilic microorganisms (including yeasts). However,
there have been an increasing number of studies on psychrophilic yeasts sharing
the non-Antarctic cryosphere. The present paper provides an overview of
the distribution and adaptation strategies of psychrophilic yeasts worldwide.
Attention is also focused on their biotechnological potential, especially on their
exploitation as a source of cold-active enzymes and for bioremediation purposes
Molecular two-step strategy to select inter-species Saccharomyces hybrids
No full textHybridization is a common tool to improve yeast for wine industry. Using non-GE hybridization techniques a lot of attempts lead to failed mating which is mainly caused by low spore viability and haplo-selfing. This work proposed a two-step molecular strategy to validate inter-species Saccharomyces hybrids rapidly
Knufia obscura sp. nov. and Knufia victoriae sp. nov., two new species from extreme environments
No full textSix strains of black meristematic fungi were isolated from Antarctic soils, gasoline car tanks and from the marine alga Flabellia petiolata. These fungi were characterized by morphological, physiological and phylogenetic analyses. According to the maximum-likelihood analysis reconstructed with ITS and LSU sequences, these strains belonged to the genus Knufia. Knufia obscura sp. nov. (holotype CBS 148926) and Knufia victoriae sp. nov. (holotype CBS 149015) are proposed as two novel species and descriptions of their morphological, physiological and phylogenetic features are presented. Based on the maximum-likelihood analyses, K. obscura was closely related to Knufia hypolithi (99 % bootstrap support), while K. victoriae clustered in the clade of Knufia cryptophialidica and Knufia perfecta (93 % bootstrap support). Knufia victoriae, recorded in Antarctic soil samples, had a psychrophilic behaviour, with optimal growth between 10 and 15 °C and no growth recorded at 20 °C. Knufia obscura, from a gasoline car tank and algae, displayed optimal growth between 20 and 25 °C and was more tolerant to salinity than K. victoriae
Screening of new Yeast Strains of Saccharomycodes ludwigii and Zygosaccharomyces rouxii for producing Low-Alcohol Beer.” poster al VII International Technical Symposium on “Advanced food processing and quality management
No full textIn vitro antimycotic activity of galloyl-derivatives extracted from leaves of Camellia sinensis towards yeast and yeast-like strains. XXII Int. Conference on Polyphenols.
No full textDynamics of organic matter and microbial populations in amended soil: a multidisciplinary approach
No full textQuality control of malt: turbidity problems of standard worts given by the presence of microbial cells
No full textSince the main effect on beer colour originates from the chemical composition of malt, the measurement of the colour of won obtained from malt is one of the most important quality parameters to be controlled. Malt colour determination is usually performed spectrophotometrically on EBC Congress worts, which are generally bright. The quality control on the malt harvested in the year 2007 highlighted a problem of turbid Congress wort, for a part of Northern Europe samples analyzed, and therefore the spectrophotometric determination of the colour of wort was not possible. Thus both analytical screening of the quality parameters of malt and the scanning electron microscope (SEM) were used to identify the nature of the turbidity in the worts. The results obtained suggested that the nature of the turbidity of Congress worts could have been due to microbial contamination of the barley, enhanced in particular by the rainy harvest and the consequent formation of exopolysaccharides (EPS) by stressed yeast and bacteria during malting
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