Influence of Culture and Nutritional Conditions on Self-Flocculation of a Kloeckera apiculata Wine Strain

U radu je ispitan utjecaj uvjeta okoline na kontrolu spontane flokulacije kvasca Kloeckera apiculata mc1, izoliranog iz argentinskoga grožđa, koji dokazano poboljšava aromu vina. Povećanje temperature izravno je utjecalo na flokulaciju, omogućavajući veće povezivanje zimolektina, određenih pomoću fluorescentne probe BSA-Gal-FITC i kvantificiranih Scatchardovim modelom. Miješanje je pozitivno utjecalo na flokulaciju kvasca, a nije povećalo indeks hidrofobnosti. Flokulaciju je ubrzao dodatak glukoze, fruktoze i etanola podlozi od kvasca i dušičnih baza, bez naknadnog dodavanja aminokiselina ili amonijeva sulfata. Dodatak asimilativnog dušika bez izvora energije negativno je utjecao na flokulaciju. Tijekom proizvodnje vina flokulacija se može kontrolirati podešavanjem uvjeta okoline, kao što su temperatura i hranjive tvari, radi optimiranja procesa i kakvoće gotovog proizvoda. Pomoću parametara flokulacije može se predvidjeti ponašanje vinskoga kvasca Kloeckera apiculata mc1 tijekom fermentacije.The current work examines the environmental conditions to control the expression of self-flocculation of Kloeckera apiculata mc1 isolated from Argentinian grapes with proven beneficial effect on wine aroma. Temperature had a direct effect on the expression of flocculation resulting in an increase in the number of zymolectin sites determined with a BSA-Gal-FITC probe and quantified with the Scatchard plot. Agitation had a positive effect on yeast flocculation and the effect did not correlate with an increase in the hydrophobic index. The addition of glucose, fructose or ethanol to yeast nitrogen base medium without amino acids or ammonium sulphate stimulated flocculation. Assimilative nitrogen sources had a negative impact on flocculation in the absence of an energy source. During winemaking, control of flocculation by environmental factors such as temperature and the presence of nutrients could be applied in order to optimize the fermentation process and hence the quality of the final product. Knowledge of the effect of different parameters on flocculation of the wine yeast K. apiculata mc1 allows prediction of the behaviour of this yeast during fermentation

Phylodynamics of Hepatitis C Virus Subtype 2c in the Province of Córdoba, Argentina

The Hepatitis C Virus Genotype 2 subtype 2c (HCV-2c) is detected as a low prevalence subtype in many countries, except in Southern Europe and Western Africa. The current epidemiology of HCV in Argentina, a low-prevalence country, shows the expected low prevalence for this subtype. However, this subtype is the most prevalent in the central province of Córdoba. Cruz del Eje (CdE), a small rural city of this province, shows a prevalence for HCV infections of 5%, being 90% of the samples classified as HCV-2c. In other locations of Córdoba Province (OLC) with lower prevalence for HCV, HCV-2c was recorded in about 50% of the samples. The phylogenetic analysis of samples from Córdoba Province consistently conformed a monophyletic group with HCV-2c sequences from all the countries where HCV-2c has been sequenced. The phylogeographic analysis showed an overall association between geographical traits and phylogeny, being these associations significant (α = 0.05) for Italy, France, Argentina (places other than Córdoba), Martinique, CdE and OLC. The coalescence analysis for samples from CdE, OLC and France yielded a Time for the Most Common Recent Ancestor of about 140 years, whereas its demographic reconstruction showed a “lag” phase in the viral population until 1880 and then an exponential growth until 1940. These results were also obtained when each geographical area was analyzed separately, suggesting that HCV-2c came into Córdoba province during the migration process, mainly from Europe, which is compatible with the history of Argentina of the early 20th century. This also suggests that the spread of HCV-2c occurred in Europe and South America almost simultaneously, possibly as a result of the advances in medicine technology of the first half of the 20th century

La renovación de la palabra en el bicentenario de la Argentina : los colores de la mirada lingüística

El libro reúne trabajos en los que se exponen resultados de investigaciones presentadas por investigadores de Argentina, Chile, Brasil, España, Italia y Alemania en el XII Congreso de la Sociedad Argentina de Lingüística (SAL), Bicentenario: la renovación de la palabra, realizado en Mendoza, Argentina, entre el 6 y el 9 de abril de 2010. Las temáticas abordadas en los 167 capítulos muestran las grandes líneas de investigación que se desarrollan fundamentalmente en nuestro país, pero también en los otros países mencionados arriba, y señalan además las áreas que recién se inician, con poca tradición en nuestro país y que deberían fomentarse. Los trabajos aquí publicados se enmarcan dentro de las siguientes disciplinas y/o campos de investigación: Fonología, Sintaxis, Semántica y Pragmática, Lingüística Cognitiva, Análisis del Discurso, Psicolingüística, Adquisición de la Lengua, Sociolingüística y Dialectología, Didáctica de la lengua, Lingüística Aplicada, Lingüística Computacional, Historia de la Lengua y la Lingüística, Lenguas Aborígenes, Filosofía del Lenguaje, Lexicología y Terminología

Behaviour of Kloeckera apiculata Flocculent Strain in Coculture with Saccharomyces cerevisiae

The behaviour of the flocculent Kloeckera apiculata strain in coculture with the nonflocculent Saccharomyces cerevisiae strain, both yeasts isolated from wine, has been analyzed. Pure culture of Kloeckera apiculata (apiculate yeast) exhibits 75 % flocculation in the yeast extract/peptone/glucose (containing 20 g/L of glucose, YPG20) medium after 24-hour incubation at 28 °C. This yeast expresses a weak flocculent phenotype in glucose-poor medium (10 % of flocculated cells). Increasing the glucose concentrations in this medium induces yeast flocculation. When the apiculate yeast was co-inoculated with a nonflocculent strain of Saccharomyces cerevisiae (elliptic yeast), an increase of the number of elliptic cells that settled at the bottom of the culture was observed. Electron microscopy observations of the aggregates formed in the mixed culture confirmed that apiculate and elliptic yeasts can interact and establish a binding between them through homogeneous mucus. However, a lower percentage of Kloeckera apiculata flocculation with respect to the pure cultures was observed, this behaviour being correlated with a higher rate of glucose consumption by Saccharomyces cerevisiae. The prompt coflocculation of Kloeckera apiculata with Saccharomyces strains and the induction of this phenomenon by glucose could be considered an important biotechnological tool for the early decreasing of indigenous saccharomycetic flora from the media, before the inoculation of a selected starter strain to carry out a more controlled alcohol fermentation

Međusobno djelovanje flokulirajućeg soja kvasca Kloeckera apiculata i kvasca Saccharomyces cerevisiae

The behaviour of the flocculent Kloeckera apiculata strain in coculture with the nonflocculent Saccharomyces cerevisiae strain, both yeasts isolated from wine, has been analyzed. Pure culture of Kloeckera apiculata (apiculate yeast) exhibits 75 % flocculation in the yeast extract/peptone/glucose (containing 20 g/L of glucose, YPG20) medium after 24-hour incubation at 28 °C. This yeast expresses a weak flocculent phenotype in glucose-poor medium (10 % of flocculated cells). Increasing the glucose concentrations in this medium induces yeast flocculation. When the apiculate yeast was co-inoculated with a nonflocculent strain of Saccharomyces cerevisiae (elliptic yeast), an increase of the number of elliptic cells that settled at the bottom of the culture was observed. Electron microscopy observations of the aggregates formed in the mixed culture confirmed that apiculate and elliptic yeasts can interact and establish a binding between them through homogeneous mucus. However, a lower percentage of Kloeckera apiculata flocculation with respect to the pure cultures was observed, this behaviour being correlated with a higher rate of glucose consumption by Saccharomyces cerevisiae. The prompt coflocculation of Kloeckera apiculata with Saccharomyces strains and the induction of this phenomenon by glucose could be considered an important biotechnological tool for the early decreasing of indigenous saccharomycetic flora from the media, before the inoculation of a selected starter strain to carry out a more controlled alcohol fermentation.U radu je istraženo međusobno djelovanje flokulirajućeg soja kvasca Kloeckera apiculata u mješovitoj kulturi i neflokulirajućeg soja kvasca Saccharomyces cerevisiae. Oba su kvasca izolirana iz vina. Uzgojena je čista kultura stanica kvasca K. apiculata na podlozi od ekstrakta kvasca, peptona i glukoze, pa je nakon 24-satne inkubacije pri 28 °C utvrđeno da ih je flokulirano 75 %. U podlozi s malom koncentracijom glukoze ovaj se kvasac pojavljuje kao slabo flokulirajući fenotip (s 10 % flokulirajucih stanica). Povećanje koncentracije glukoze dovodi do porasta broja flokuliranih stanica. Pri uzgoju soja K. apiculata u mješovitoj kulturi s eliptičnim stanicama neflokulirajućeg soja S. cerevisiae opaženo je da se veći broj eliptičnih stanica taloži na dno posude. Pregledom agregata nastalih u mješovitoj kulturi elektronskim mikroskopom potvrđeno je da stanice kvasca K. apiculata i eliptične stanice mogu međusobno reagirati i povezati se u homogeni sluzavi talog. Budući da je kvascu S. cerevisiae za rast potrebno više glukoze, u mješovitoj je kulturi utvrđen i manji postotak flokulacije kvasca K. apiculata. Uspješna flokulacija kvasca K. apiculata sa sojem Saccharomyces, ubrzana dodatkom glukoze, može se primijeniti kao biotehnološki postupak za brzo smanjenje autohtone flore saharomiceta u podlozi, prije inokulacije odabranom starter-kulturom, kako bi se postigla veća kontrola alkoholnog vrenja

Perfil epidemiológico molecular de la infección por el virus de la Hepatitis C en la región central de Argentina

La presencia de RNA-HCV y la distribución de genotipos se detectaron mediante técnicas moleculares (RT-nested PCR y RFLP) en 310 muestras de individuos de la región centro de Argentina. Se halló 11,8% de coinfección HCV/HIV, con mayor prevalencia de genotipo 1 (73%). La distribución de los genotipos 1 y 2 entre individuos monoinfectados fue de 49,4% y 43,9%, respectivamente. El análisis de regresión logística multivariado mostró que la edad y el uso de drogas endovenosas (UDEV) condicionó la distribución de genotipos. El genotipo 2 se halló frecuentemente entre adultos mayores y su diseminación no se pudo asociar a ninguna vía de transmisión. El genotipo 1 se lo halló principalmente en adultos jóvenes y asociados al UDEV. El notable incremento de genotipo 1, homogéneamente distribuido en todas las edades posee importantes implicancias en las decisiones terapéuticas, considerando que posee baja respuesta a la terapia antiviral