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Durante la fermentación malolática (FML) las bacterias del ácido láctico (BAL) decarboxilan el ácido L-málico transformándolo en ácido L-láctico y contribuyen a la calidad del vino al reducir su acidez y aportar a su aroma y sabor. De este modo, las BAL aportan al terroir característico de cada vino, y su diversidad en el viñedo dependerá de factores como clima, suelo, varietal vínico y prácticas culturales y de vinificación. En la región vitícola bonaerense (Argentina) no existen aún estudios sobre la diversidad microbiológica asociada a suelos, vides, mostos y vinos, conocimiento crucial para seleccionar cepas indígenas con fines enológicos. Para iniciar este análisis se realizó la secuenciación masiva del gen 16S rRNA de muestras de suelo, rizósfera, mosto y vinos de dos bodegas del SO bonaerense (Saldungaray y Al Este, Buenos Aires, Argentina), obteniéndose 123.379 secuencias y 5.323 OTUs. Se observaron índices de diversidad elevados, con diferencias significativas entre muestras de suelo y rizósfera respecto de mosto y vino. Los análisis taxonómicos mostraron como filo mayoritario en suelo y rizósfera a Proteobacteria (especialmente Alphaproteobacteria, con predominancia de Rhizobiales), y en mosto y vino a Proteobacteria, con predominancia de las Alphaproteobacteria Rhodospirillales y Sphingomonadales. Estos hallazgos, constituyen un primer aporte al conocimiento de las comunidades bacterianas de una región vitivinícola en desarrollo y contribuirán a optimizar procesos productivos y prácticas agrícolas sustentables. Trabajo en relación con PIT AP-BA Número 173/16, presentado en Jornadas de Jóvenes Investigadores en la Universidad Federal de San Carlos (UFSCAR), Brasil.

© 2019 Elsevier B.V. All rights reserved., In the search for new antimicrobial molecules, antimicrobial peptides (AMPs) offer a viable alternative to conventional antibiotics, as they physically disrupt the bacterial membranes, leading to membrane disruption and eventually cell death. In particular, the group of linear α-helical cationic peptides has attracted increasing research and clinical interest. The AMP P5 has been previously designed as a cationic linear α-helical sequence, being its antimicrobial and hemolytic properties also evaluated. In this work, we analyzed the feasibility of using P5 against a carbapenem-resistant clinical isolate of Pseudomonas aeruginosa, one of the most common and risky pathogens in clinical practice. After antimicrobial activity confirmation in in vitro studies, synergistic activity of P5 with meropenem was evaluated, showing that P5 displayed significant synergistic activity in a time kill curve assay. The ability of P5 to permeabilize the outer membrane of P. aeruginosa can explain the obtained results. Finally, the antibiofilm activity was investigated by viability analysis (MTT assay), crystal violet and confocal imaging, with P5 displaying mild biofilm inhibition in the range of concentrations tested. Regarding biofilm disruption activity, P5 showed a higher efficacy, interfering with biofilm structure and promoting bacterial cell death. Atomic force microscope images further demonstrated the peptide potential in P. aeruginosa biofilm eradication, confirming the promising application of P5 in multi-resistant infections therapeutics., This work was supported by grants from Agencia Nacional de Promoción Científica y Tecnológica, Ministerio de Ciencia y Tecnología, Argentina (PICT 2016-0478 and PICT 2017-2349), CONICET (PIP-2014-11220130100383CO), Universidad Nacional de Quilmes (Programa Microbiología Molecular Básica y Aplicada) and Fundação para a Ciência e a Tecnologia – Ministério da Ciência, Tecnologia e Ensino Superior (FCT-MCTES, Portugal). LS is a member of the Research Career of CIC-BA. AH and PCM are members of the Carrera del Investigador Cientıfico y Tecnologico (CONICET, Argentina). MM. and PM acknowledge fellowships from CONICET.

Trabajo presentado al XVII Congreso Argentino de Ciencia y Tecnología de los Alimentos y al XXI Congreso Latinoamericano y del Caribe de Ciencia y Tecnología de Alimentos (CyTAL-ALACCTA), celebrados en Buenos Aires del 20 al 22 de noviembre de 2019.

Brizuela, Natalia S. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Instituto de Microbiología Básica y Aplicada. Laboratorio de Microbiología Molecular y CONICET; Argentina Bravo-Ferrada, Bárbara M. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Instituto de Microbiología Básica y Aplicada. Laboratorio de Microbiología Molecular y CONICET; Argentina Curilén, Yolanda. Universidad Nacional del Comahue. Facultad de Ciencia y Tecnología de los Alimentos y PROBIEN, CONICET-UNCo; Argentina Delfederico, Lucrecia. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Instituto de Microbiología Básica y Aplicada. Laboratorio de Microbiología Molecular; Argentina Caballero, Adriana. Universidad Nacional del Comahue. Facultad de Ciencia y Tecnología de los Alimentos y PROBIEN, CONICET-UNCo; Argentina Semorile, Liliana. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Instituto de Microbiología Básica y Aplicada. Laboratorio de Microbiología Molecular y CIC-BA; Argentina Pozo-Bayón, M. Ángeles. Universidad Autónoma de Madrid. Instituto de Investigación en Ciencias de la Alimentación, Cons. Sup. de Investigaciones Científicas; Spain Tymczyszyn, E. Elizabeth. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Instituto de Microbiología Básica y Aplicada. Laboratorio de Microbiología Molecular y CONICET; Argentina Brizuela NS, Bravo-Ferrada BM, Curilén Y, Delfederico L, Caballero A, Semorile L, Pozo-Bayón MÁ y Tymczyszyn EE (2018). Advantages of Using Blend Cultures of Native L. plantarum and O. oeni Strains to Induce Malolactic Fermentation of Patagonian Malbec Wine. Front. Microbiol. 9:2109. doi: 10.3389/fmicb.2018.02109 The malolactic fermentation (MLF) of Patagonian Malbec wine inoculated with blend cultures of selected native strains of Lactobacillus plantarum and Oenococcus oeni was monitored during 14 days, analyzing the strains ability to modify the content of some organic acids and to change the volatile compounds profile. The performance of the LAB strains was tested as single and blends cultures of both species. An implantation control by RAPD PCR was also carried out to differentiate among indigenous and inoculatedstrains. The L. plantarum strains UNQLp11 and UNQLp155 and the O. oeni strain UNQOe73.2 were able to remain viable during the monitoring time of MLF, whereas the O. oeni strain UNQOe31b showed a decrease of five log CFU at day 14. The four strains assayed showed a similar behavior in wine whether they were inoculated individually or as blend cultures. All strains were able to consume L-malic acid, particularly the L. plantarum strains, which showed the highest consumption values at day 14, both as single or blend cultures. The changes in the volatile compounds profile of Malbec wine samples, before and after MLF, were determined by HS-SPME and GC-MS technique. Wines inoculated with blend cultures containing strain UNQLp155 showed a decrease in the total alcohols content and an increase in the total esters content. On the other hand, wines inoculated with single cultures of strains UNQLp155, UNQOe31b or UNQOe73.2 showed no significant decrease in the total alcohols concentration but a significant increase in the total esters content. When strain UNQLp11 was inoculated as single or as blend culture with strain UNQOe31b, wines exhibited an increase in the total alcohols content, and a decrease in the total esters content. The content of diethyl succinate showed the greatest increase at final of MLF, and a particular synergistic effect in its synthesis was observed with a blend culture of strains UNQLp155 and UNQOe73.2. These results suggest that the use of blend cultures formulated with strains belonging to L. plantarum and O. oeni species could offer an interesting advantage to induce MLF in Malbec wines, contributing to diversify their aromatic profiles. Con referato

In previous works, it was shown that S-layer proteins from Lactobacillus kefir were able to recrystallize and stabilize liposomes, this feature reveling a great potential for developing liposomal-based carriers. Despite previous studies on this subject are important milestones, a number of questions remain unanswered. In this context, the feasibility of S-layer proteins as a biomaterial for drug delivery was evaluated in this work. First, S-layer proteins were fully characterized by electron microscopy, 2D-electrophoresis, and anionic exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). Afterward, interactions of S-layer proteins with model lipid membranes were evaluated, showing that proteins adsorb to the lipid surface following a non-fickean or anomalous diffusion, when positively charged lipid were employed, suggesting that electrostatic interaction is a key factor in the recrystallization process on these proteins. Finally, the interaction of S-layer coated liposomes with Caco-2 cell line was assessed: First, cytotoxicity of formulations was tested showing no cytotoxic effects in S-layer coated vesicles. Second, by flow cytometry, it was observed an increased ability to transfer cargo molecules into Caco-2 cells from S-layer coated liposomes in comparison to control ones. All data put together, supports the idea that a combination of adhesive properties of S-layer proteins concomitant with higher stability of S-layer coated liposomes represents an exciting starting point in the development of new drug carriers.

Shiga toxin (Stx) is the principal virulence factor during Shiga toxin-producing Escherichia coli (STEC) infections. We have previously reported the inactivation of bacteriophage encoding Stx after treatment with chitosan, a linear polysaccharide polymer with cationic properties. Cationic antimicrobial peptides (cAMPs) are short linear aminoacidic sequences, with a positive net charge, which display bactericidal or bacteriostatic activity against a wide range of bacterial species. They are promising novel antibiotics since they have shown bactericidal effects against multiresistant bacteria. To evaluate whether cationic properties are responsible for bacteriophage inactivation, we tested seven cationic peptides with proven antimicrobial activity as anti-bacteriophage agents, and one random sequence cationic peptide with no antimicrobial activity as a control. We observed bacteriophage inactivation after incubation with five cAMPs, but no inactivating activity was observed with the random sequence cationic peptide or with the non-alpha helical cAMP Omiganan. Finally, to confirm peptide-bacteriophage interaction, zeta potential was analyzed by following changes on bacteriophage surface charges after peptide incubation. According to our results we could propose that: (1) direct interaction of peptides with phage is a necessary step for bacteriophage inactivation, (2) cationic properties are necessary but not sufficient for bacteriophage inactivation, and (3) inactivation by cationic peptides could be sequence (or structure) specific. Overall our data suggest that these peptides could be considered a new family of molecules potentially useful to decrease bacteriophage replication and Stx expression. Fil: del Cogliano, Manuel Eugenio. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Ingeniería Genética y Biología Molecular y Celular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Hollmann, Axel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; Argentina. Universidad Nacional de Quilmes; Argentina Fil: Martínez, Melina María Belén. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnologia. Instituto de Microbiologia Basica y Aplicada. Laboratorio de Micologia Molecular.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Semorile, Liliana Carmen. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnologia. Instituto de Microbiologia Basica y Aplicada. Laboratorio de Micologia Molecular.; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Ingeniería Genética y Biología Molecular y Celular; Argentina Fil: Ghiringhelli, Pablo Daniel. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Ingeniería Genética y Biología Molecular y Celular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Maffia, Paulo Cesar. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnologia. Instituto de Microbiologia Basica y Aplicada. Laboratorio de Micologia Molecular.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Bentancor, Leticia Verónica. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Ingeniería Genética y Biología Molecular y Celular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Background and Aims:Information regarding the composition and dynamics of microbial communities through-out winemaking is always valuable to control the process and contributes to improving the quality of wine. The aimsof this work were to analyse the diversity of lactic acid bacteria (LAB) species present during the spontaneousmalolactic fermentation (MLF) of Patagonian red wines, and to isolate and identify native LAB species.Methods and Results:Samples of Merlot and Pinot Noir wines were collected during three vintages at onecommercial cellar. Through polymerase chain reaction (PCR)-rpoB/denaturing gradient gel electrophoresis (DGGE),it was possible to identify 15 LAB species and through PCR-16S rRNAV3 region/DGGE, 11 LAB species, duringspontaneous MLF of these wines, mostly,Oenococcus oeniandLactobacillus plantarum. These two species were alsolargely recovered by culture and analysed by the random amplified polymorphic DNA–PCR technique. Isolates ofthese two LAB species exhibited considerable genotypic heterogeneity.Conclusions:The prevalence ofO. oeniandLb. plantarumin all samples suggests that both species are involved inleading the spontaneous MLF of these Patagonian wines. The analysis of the LAB microbiota in wine by PCR-DGGEusing two gene regions enabled addition to the number of species that can usually be detected during MLF.Significance of the Study:The study offered a more complete knowledge of the LAB community present in winesin a cellar in the Argentine Patagonia during the spontaneous MLF. Our findings are particularly relevant, becausethey contribute to the possibility of designing an MLF starter composed of native strains ofLb. plantarumandO. oeni Fil: Valdes la Hens, Danay. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Microbiología Molecular; Argentina Fil: Bravo Ferrada, Barbara Mercedes. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Microbiología Molecular; Argentina Fil: Delfederico, Lucrecia. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Microbiología Molecular; Argentina Fil: Caballero, Adriana Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. IDEPA - Subsede San Antonio Oeste; Argentina. Universidad Nacional del Comahue; Argentina Fil: Semorile, Liliana Carmen. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Microbiología Molecular; Argentina

Temas del informe: Línea de Investigación “Estudio de bacterias del ácido láctico de origen enológico indígenas de la Patagonia”. Línea de Investigación “Modulación de superficies de nanopartículas por efecto transmembrana en bicapas lipídicas soportadas en estructuras poliméricas”. Línea de Investigación “Liposomas estabilizados con proteínas de capa S de lactobacilos”. Línea de Investigación “Estudio de la diversidad de bacterias de interés tecnológico en alimentos fermentados artesanales”. Línea de Investigación “Desarrollo de biomoléculas anti-infecciosas”.