Search

Myotis is the most diverse genus of bats in the world, with more than 30 species recognized in the Neotropics. However, many of these species represent cryptic complexes and are evidence of the existence of hidden diversity in several regions. Using an integrative approach based on molecular, morphological, and bioacoustic data, we performed a systematic review of Myotis species from Chile. Phylogenetic inference using cytochrome-b indicated the existence of three monophyletic lineages, and qualitative and quantitative morphological analyses supported these lineages as distinct and morphologically diagnosable taxa. Analysis of discriminant functions using parameters of echolocation calls also indicates the existence of three distinct bioacoustic clusters. Thus, all lines of evidence congruently indicate the existence of three distinct taxa. As a result, we recognize Myotis arescens as a valid and distinct species and define its taxonomic limits from the other species from Chile, Myotis atacamensis and Myotis chiloensis.

The yeast Saccharomyces cerevisiae is the main species responsible for the process that involves the transformation of grape must into wine, with the initial nitrogen in the grape must being vital for it. One of the main problems in the wine industry is the deficiency of nitrogen sources in the grape must, leading to stuck or sluggish fermentations, and generating economic losses. In this scenario, an alternative is the isolation or generation of yeast strains with low nitrogen requirements for fermentation. In the present study, we carry out a genetic improvement program using as a base population a group of 70 strains isolated from winemaking environments mainly in Chile and Argentina (F0), making from it a first and second filial generation (F1 and F2, respectively) based in different families and hybrids. It was found that the trait under study has a high heritability, obtaining in the F2 population strains that consume a minor proportion of the nitrogen sources present in the must. Among these improved strains, strain “686” specially showed a marked drop in the nitrogen consumption, without losing fermentative performance, in synthetic grape must at laboratory level. When using this improved strain to produce wine from a natural grape must (supplemented and non-supplemented with ammonium) at pilot scale under wine cellar conditions, a similar fermentative capacity was obtained between this strain and a widely used commercial strain (EC1118). However, when fermented in a non-supplemented must, improved strain “686” showed the presence of a marked floral aroma absent for EC1118 strain, this difference being probably a direct consequence of its different pattern in amino acid consumption. The combination of the capacity of improved strain “686” to ferment without nitrogen addition and produce floral aromas may be of commercial interest for the wine industry. EEA Mendoza Fil: Kessi Pérez, Eduardo Ignacio. Universidad de Santiago de Chile. Departamento de Ciencia y Tecnología de los Alimentos; Chile Fil: Kessi Pérez, Eduardo Ignacio. Universidad de Santiago de Chile. Centro de Estudios en Ciencia y Tecnología de Alimentos (CECTA); Chile Fil: Molinet, Jennifer. Universidad de Santiago de Chile. Departamento de Ciencia y Tecnología de los Alimentos; Chile Fil: García, Verónica. Universidad de Santiago de Chile. Centro de Estudios en Ciencia y Tecnología de Alimentos (CECTA); Chile Fil: Aguilera, Omayra. Universidad de Santiago de Chile. Centro de Estudios en Ciencia y Tecnología de Alimentos (CECTA); Chile Fil: Cepeda, Fernanda. Universidad de Chile. Facultad de Ciencias Agronómicas. Laboratorio de Genética y Biotecnología en Acuicultura, Departamento de Producción Animal; Chile Fil: López, María Eugenia. Universidad de Chile. Facultad de Ciencias Agronómicas. Laboratorio de Genética y Biotecnología en Acuicultura, Departamento de Producción Animal; Chile Fil: Sari, Santiago Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Cuello, Raúl Andrés. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Cuello, Raúl Andrés. Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET); Argentina Fil: Ciklic, Ivan Francisco. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Rojo, Maria Cecilia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Rojo, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina Fil: Combina, Mariana. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Combina, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina Fil: Araneda, Cristián. Universidad de Chile. Facultad de Ciencias Agronómicas. Laboratorio de Genética y Biotecnología en Acuicultura, Departamento de Producción Animal; Chile Fil: Martínez, Claudio. Universidad de Santiago de Chile. Departamento de Ciencia y Tecnología de los Alimentos; Chile Fil: Martínez, Claudio. Universidad de Santiago de Chile. Centro de Estudios en Ciencia y Tecnología de Alimentos (CECTA); Chile

BackgroundSaccharomyces cerevisiae is the main microorganism responsible for alcoholic fermentation. In this process, the consumption of nitrogen is of great importance since it is found in limiting quantities and its deficiency produces sluggish and/or stuck fermentations generating large economic losses in the wine-making industry. In a previous work we compared the transcriptional profiles between genetically related strains with differences in nitrogen consumption, detecting genes with differential expression that could be associated to the differences in the levels of nitrogen consumed. One of the genes identified was ICY1. With the aim of confirming this observation, in the present work we evaluated the consumption of ammonium during the fermentation of strains that have deleted or overexpressed this gene.ResultsOur results confirm the effect of ICY1 on nitrogen uptake by evaluating its expression in wine yeasts during the first stages of fermentation under low (MS60) and normal (MS300) assimilable nitrogen. Our results show that the mRNA levels of ICY1 diminish when the amount of assimilable nitrogen is low. Furthermore, we constructed strains derived from the industrial strain EC1118 as a null mutant in this gene as well as one that overexpressed it.ConclusionsOur results suggest that the expression of ICY1 is regulated by the amount of nitrogen available in the must and it is involved in the consumption of ammonium, given the increase in the consumption of this nitrogen source observed in the null mutant strain.

Different populations within a species represent a rich reservoir of allelic variants, corresponding to an evolutionary signature of withstood environmental constraints. Saccharomyces cerevisiae strains are widely utilised in the fermentation of different kinds of alcoholic beverages, such as, wine and sake, each of them derived from must with distinct nutrient composition. Importantly, adequate nitrogen levels in the medium are essential for the fermentation process, however, a comprehensive understanding of the genetic variants determining variation in nitrogen consumption is lacking. Here, we assessed the genetic factors underlying variation in nitrogen consumption in a segregating population derived from a cross between two main fermenter yeasts, a Wine/European and a Sake isolate. By linkage analysis we identified 18 main effect QTLs for ammonium and amino acids sources. Interestingly, majority of QTLs were involved in more than a single trait, grouped based on amino acid structure and indicating high levels of pleiotropy across nitrogen sources, in agreement with the observed patterns of phenotypic co-variation. Accordingly, we performed reciprocal hemizygosity analysis validating an effect for three genes, GLT1, ASI1 and AGP1. Furthermore, we detected a widespread pleiotropic effect on these genes, with AGP1 affecting seven amino acids and nine in the case of GLT1 and ASI1. Based on sequence and comparative analysis, candidate causative mutations within these genes were also predicted. Altogether, the identification of these variants demonstrate how Sake and Wine/European genetic backgrounds differentially consume nitrogen sources, in part explaining independently evolved preferences for nitrogen assimilation and representing a niche of genetic diversity for the implementation of practical approaches towards more efficient strains for nitrogen metabolism.