Molecular-genetic analysis of the structural determinants and primary functions of eukaryotic ribosomal proteins L16 y L19 in Saccharomyces cerevisiae

Resumen del póster presentado al "XXXV Congreso de la SEB-BM/37th FEBS/22nd IUBMB" celebrados en Sevilla del 4 al 9 de septiembre de 2012.Peer Reviewe

Biotechnological Potential and Safety Evaluation of Dextran- and Riboflavin-Producing Weisella cibaria Strains for Gluten-Free Baking

Gluten consumption causes several immunological and non-immunological intolerances in susceptible individuals. In this study, the dextran-producing Weissella cibaria BAL3C-5 and its derivative, the riboflavin-overproducing strain BAL3C-5 C120T, together with a commercial bakery yeast, were used to ferment gluten-free (GF)-doughs obtained from corn and rice flours at two different concentrations and supplemented with either quinoa, buckwheat, or chickpea to obtain laboratory-scale GF bread. The levels of dextran, riboflavin, and total flavins were determined in the fermented and breads. Both strains grew in fermented doughs and contributed dextran, especially to those made with corn plus quinoa (~1 g/100 g). The highest riboflavin (350–150 µg/100 g) and total flavin (2.3–1.75 mg/100 g) levels were observed with BAL3C-5 C120T, though some differences were detected between the various doughs or breads, suggesting an impact of the type of flour used. The safety assessment confirmed the lack of pathogenic factors in the bacterial strains, such as hemolysin and gelatinase activity, as well as the genetic determinants for biogenic amine production. Some intrinsic resistance to antibiotics, including vancomycin and kanamycin, was found. These results indicated the microbiological safety of both W. cibaria strains and indicated their potential application in baking to produce GF bread.This research was funded in Spain by the Spanish Ministry of Science and Innovation (grant RTI2018-097114-B-I00), by the Basque Government (grants IT1662-22 and PIBA_2020_1_0032) and by CSIC (grant 2022AEP028). This research was funded in Italy by the Italian Ministry of University and Research Project PE0000003 P.R. is the beneficiary of a grant by the University of Milan in the framework of “Linea 2—A. 2022”

Diversity of microorganisms and their metabolites in food

Throughout history as well as the present, food microorganisms have been proven to play a significant role in human life. Some of them appear to contaminate food during storage and cause spoilage. Foodborne microorganisms that do not cause any bad smell and have no taste or surface appearance on food, such as Salmonella spp., Escherichia spp., and Listeria spp., are of particular concern. Because of these characteristics, these microorganisms are the most troublesome, and their presence in food often leads to foodborne outbreaks. To prevent their multiplication, chemical preservatives are usually included as an ingredient in food. Nonetheless, consumers’ demand for more natural and minimally processed food promotes the use of other, more naturally occurring, alternatives. Microorganisms whose metabolites possess antimicrobial properties have been utilized in natural food preservation and introduced to the food industry

Yeast biodiversity in fermented doughs and raw cereal matrices and the study of technological traits of selected strains isolated in spain

43 páginas, 12 tablas, 8 figurasBakers use pure microorganisms and/or traditional sourdoughs as the leavening agent for making bread. The performance of each starter and the substances produced by the microorganisms greatly affect the dough rheology and features of breads. Modern sourdoughs inoculated with selected lactic acid bacteria and yeasts are microbiologically stable, safer than traditional sourdoughs, and easy to use. However, the commercial repertoire of baker’s yeasts is still limited. Therefore, there is a demand for new strains of yeast species, capable of conferring distinctive traits to breads made from a variety of agri-food matrices, in the design of innovative starters. In this context, we report the first comprehensive study on yeasts isolated from a wide range of fermented doughs, cereal flours, and grains of Spain. Nine yeast species were identified from 433 isolates, which were distributed among separate clades. Moreover, phenotypic traits of potential technological relevance were identified in selected yeast strains. Mother doughs (MDs) showed the greatest yeast biodiversity, whereas commercial Saccharomyces starters or related and wild strains often dominated the bakery doughs. A metataxonomic analysis of wheat and tritordeum MDs revealed a greater richness of yeast species and percentage variations related to the consistency, flour type, and fermentation time of MDs.This work was supported by Projects PROPAN (IPT-2012-1321-06000) and InnoStarPan (RTC-2015-4391), funded by the Spanish Ministry of Science and Innovation (MICINN) and FEDERPeer reviewe

Lactic Acid Bacteria Isolated from Fermented Doughs in Spain Produce Dextrans and Riboflavin

Many lactic acid bacteria (LAB) produce metabolites with applications in the food industry, such as dextran-type exopolysaccharides (EPS) and riboflavin (vitamin B2). Here, 72 bacteria were isolated from sourdoughs made by Spanish bread-makers. In the presence of sucrose, colonies of 22 isolates showed a ropy phenotype, and NMR analysis of their EPS supported that 21 of them were dextran producers. These isolates were identified by their random amplified polymorphic DNA (RAPD) patterns and their rrs and pheS gene sequences as LAB belonging to four species (Weissella cibaria, Leuconostoc citreum, Leuconostoc falkenbergense and Leuconostoc mesenteroides). Six selected strains from the Leuconostoc (3) and Weissella (3) genera grew in the absence of riboflavin and synthesized vitamin B2. The EPS produced by these strains were characterized as dextrans by physicochemical analysis, and the L. citreum polymer showed an unusually high degree of branching. Quantification of the riboflavin and the EPS productions showed that the W. cibaria strains produce the highest levels (585–685 μg/and 6.5–7.4 g/L, respectively). Therefore, these new LAB strains would be good candidates for the development of fermented foods bio-fortified with both dextrans and riboflavin. Moreover, this is the first report of riboflavin and dextran production by L. falkenbergense.This research was funded by the Spanish Ministry of Science, Innovation and Universities, (grants RTI2018-097114-B-I00 and PCIN-2017-075), by the Basque Government Industry and Education Department (grant PIBA_2020_1_0032) and by the University of the Basque Country (General Grant to Research Groups (GIU 19/014))

Lactic Acid Bacteria Isolated from Fermented Doughs in Spain Produce Dextrans and Riboflavin

Many lactic acid bacteria (LAB) produce metabolites with applications in the food industry, such as dextran-type exopolysaccharides (EPS) and riboflavin (vitamin B2). Here, 72 bacteria were isolated from sourdoughs made by Spanish bread-makers. In the presence of sucrose, colonies of 22 isolates showed a ropy phenotype, and NMR analysis of their EPS supported that 21 of them were dextran producers. These isolates were identified by their random amplified polymorphic DNA (RAPD) patterns and their rrs and pheS gene sequences as LAB belonging to four species (Weissella cibaria, Leuconostoc citreum, Leuconostoc falkenbergense and Leuconostoc mesenteroides). Six selected strains from the Leuconostoc (3) and Weissella (3) genera grew in the absence of riboflavin and synthesized vitamin B2. The EPS produced by these strains were characterized as dextrans by physicochemical analysis, and the L. citreum polymer showed an unusually high degree of branching. Quantification of the riboflavin and the EPS productions showed that the W. cibaria strains produce the highest levels (585–685 μg/and 6.5–7.4 g/L, respectively). Therefore, these new LAB strains would be good candidates for the development of fermented foods bio-fortified with both dextrans and riboflavin. Moreover, this is the first report of riboflavin and dextran production by L. falkenbergense.This research was funded by the Spanish Ministry of Science, Innovation and Universities, (grants RTI2018-097114-B-I00 and PCIN-2017-075), by the Basque Government Industry and Education Department (grant PIBA_2020_1_0032) and by the University of the Basque Country (General Grant to Research Groups (GIU 19/014))

Studies on the Coordination of Ribosomal Protein Assembly Events Involved in Prosessing and Stabiliz

Cellular production of ribosomes involves the formation of highly defined interactions between ribosomal proteins (r-proteins) and ribosomal RNAs (rRNAs). Moreover in eukaryotic cells, efficient ribosome maturation requires the transient association of a large number of ribosome biogenesis factors (RBFs) with newly forming ribosomal subunits. Here, we investigated how r-protein assembly events in the large ribosomal subunit (LSU) rRNA domain II are coordinated with each other and with the association of RBFs in early LSU precursors of the yeast Saccharomyces cerevisiae. Specific effects on the pre-ribosomal association of RBFs could be observed in yeast mutants blocked in LSU rRNA domain II assembly. Moreover, formation of a cluster of r-proteins was identified as a downstream event in LSU rRNA domain II assembly. We analyzed in more detail the functional relevance of eukaryote specific bridges established by this r-protein cluster between LSU rRNA domain II and VI and discuss how they can support the stabilization and efficient processing of yeast early LSU precursor RNAs

Yeast Biodiversity in Fermented Doughs and Raw Cereal Matrices and the Study of Technological Traits of Selected Strains Isolated in Spain

[EN] Bakers use pure microorganisms and/or traditional sourdoughs as the leavening agent for making bread. The performance of each starter and the substances produced by the microorganisms greatly affect the dough rheology and features of breads. Modern sourdoughs inoculated with selected lactic acid bacteria and yeasts are microbiologically stable, safer than traditional sourdoughs, and easy to use. However, the commercial repertoire of baker’s yeasts is still limited. Therefore, there is a demand for new strains of yeast species, capable of conferring distinctive traits to breads made from a variety of agri-food matrices, in the design of innovative starters. In this context, we report the first comprehensive study on yeasts isolated from a wide range of fermented doughs, cereal flours, and grains of Spain. Nine yeast species were identified from 433 isolates, which were distributed among separate clades. Moreover, phenotypic traits of potential technological relevance were identified in selected yeast strains. Mother doughs (MDs) showed the greatest yeast biodiversity, whereas commercial Saccharomyces starters or related and wild strains often dominated the bakery doughs. A metataxonomic analysis of wheat and tritordeum MDs revealed a greater richness of yeast species and percentage variations related to the consistency, flour type, and fermentation time of MDs

Functional analysis of L19: a regulatory role of the 60S ribosomal subunit in translation?

Comunicación presentada a la "8ª Reunión de la Red Española de Levaduras" celebrada en El Escorial del 14 al 16 de diciembre de 2011.-- et al.Peer Reviewe

Colaboración con empresas. Casos de éxito

Trabajo presentado a la Jornada "Colaboración Universidad - Empresa en el Sector Agroalimentario”, celebrada en la Universidad de Salamanca el 7 de marzo de 2017.De la investigación básica y aplicada con levaduras a la colaboración con grandes y medianas empresas del sector de la panificación.Peer reviewe