Freeze-Drying of Wine Yeasts and Oenococcus oeni and Selection of the Inoculation Conditions after Storage

Modern winemaking industry has new challenges focused on the application of preserved starter’s microbial cultures for the optimization of the fermentation process that ensuring flavor characteristics and the reproducibility of the final products obtained. Thus, the aim of the present work was to select the inoculation conditions for preselected Saccharomyces cerevisiae mc2 (SC), Kloeckera apiculata mF (KA) and Oenococcus oeni X2L (OO) after freeze-drying and storage in both pure and mixed cultures. The strains were grown in 17% Natural Grape Juice (NGJ) and then lyophilized in 10% individual sugars (glucose, fructose, sucrose, maltose and trehalose), 2.4% sodium glutamate, 4% yeast extract and NGJ by using different culture combinations: 1)- pure cultures (KA1, SC1, OO1), 2)- mixed yeast cultures (KA2, SC2), 3)- mixed microbial cultures (KA3, SC3, OO3). After lyophilization, the strains were stored for 12 months at 4 and 25°C. Viability post-lyophilization was culture/lyoprotectant-dependent while survival to storage depended on time and temperature being O. oeni the more resistant strain to the all process, then K. apiculata and S. cerevisiae, respectively. Freeze-drying of mixed KA-SC in 10% fructose and OO in 17% NGJ up to 6 months of storage at 4°C were the best conditions for the maintenance of the fermentative properties of the strains and for glycerol production. The inoculation of grape musts with KA-SC and OO lyophilized individually with low-cost lyoprotectants would ensure the proper development of the fermentation processes and glycerol synthesis, thus increasing the organoleptic characteristics of wines by a non-Saccharomyces strain. Therefore, the starter culture should include K. apiculata, S. cerevisiae and O. oeni strains.Fil: Ale, Cesar Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Otero, María Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Pasteris, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

Characterization of a bacteriocin produced by enterococcus gallinarum CRL 1826 Isolated from captive bullfrog: evaluation of its mode of action against Listeria monocytogenes and gram-negatives

Enterococcus gallinarum CRL 1826 isolated from an American bullfrog (Lithobates catesbeianus) skin inhibits the growth of Citrobacter freundii, Pseudomonas aeruginosa (bullfrog pathogens) and Listeria monocytogenes by a synergistic effect between organic acids and a bacteriocin-like molecule. This bacteriocin, named enterocin CRL 1826, showed a proteinaceous nature, heat stability and polar characteristics. Its production followed kinetics of primary metabolites synthesis reaching a maximum of 61,400 AU/mL. The minimum inhibitory and minimumbactericidal concentrations were 2,640 and 5,280 AU/mL, respectively, against L. monocytogenes. The addition of 120,000 AU/mL of enterocin to growing L. monocytogenes and Gram-negative (P. aeruginosa and C. freundii) bacteria showed bactericidal and bacteriostatic effects, respectively. However, enterocin derived-peptides had bactericidal effect only against Gram-negatives.Enterocin produced cell envelope damages and efflux of citosolic content on L. monocytogenes, while enterocin derived-peptides showed granulation and contraction of cytoplasm material on P. aeruginosa and increase in theperiplasmic space and empty cells appearance on C. freundii.Enterocin CRL 1826 is the first bacteriocin described for E. gallinarum from raniculture. It could be used as a biopreservative while the derived-peptides represent an alternative to control multi-drug resistant Gram-negatives.The antimicrobial spectrum and the stability of enterocin and its derived-peptides indicate that they could be applied in different biotechnological areas.Fil: Montel Mendoza, María Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; ArgentinaFil: Ale, Cesar Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; ArgentinaFil: Nader, Maria Elena Fatima. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Pasteris, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; Argentin

Isolation and Selection of Potentially Beneficial Autochthonous Bacteria for Piaractus mesopotamicus Aquaculture Activities

Piaractus mesopotamicus is the most produced specie in Argentinian fish culture with an annual production of 2,017 tons. Thehigh demands of specimens generated a deficit of larvae, juveniles and sexually mature adults. The high stress conditions and theincidence of diseases had intensified this deficit. Probiotics are proven to increase survival and growth rates in aquaculture. Thefirst step in the design of a putative probiotic is the selection of adequate microorganisms to boost fish health. Lactic Acid Bacteriaand Bacillus are generally accepted as probiotics in aquaculture. In this work we obtained 522 isolates from different anatomicalparts of P. mesopotamicus, with a total of 30 lactic acid bacteria (LAB) and 8 Bacillus strains submitted for the evaluation of theirbeneficial properties. Only eight of these strains were selected for further "in vivo" assays based on following criteria: production ofinhibitory metabolites and biosurfactants, screening of antagonistic activity against foodborne and pathogenic microorganisms, abilityto emulsify polar solvents and compatibility between strains. All selected microorganisms were identified by sequencing 16S RNAgene. Pure cultures of all strains herein studied are preserved in Centro de Referencia de Lactobacilos (CERELA-CONICET) andLaboratorio de Sanidad Animal of the Estación Experimental Agropecuaria Rafaela, Instituto Nacional de Tecnología Agropecuaria(INTA) culture collectionsFil: Guidoli, Marcos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Instituto de Ictiología del Nordeste; ArgentinaFil: Santinón, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Instituto de Ictiología del Nordeste; ArgentinaFil: Pasteris, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Sánchez, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Instituto de Ictiología del Nordeste; ArgentinaFil: Nader, Maria Elena Fatima. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Skin-associated lactic acid bacteria from North American bullfrogs as potential control agents of Batrachochytrium dendrobatidis

The fungal pathogen Batrachochytrium dendrobatidis (Bd) is the causative agent of chytridiomycosis and has been a key driver in the catastrophic decline of amphibians globally. While many strategies have been proposed to mitigate Bd outbreaks, few have been successful. In recent years, the use of probiotic formulations that protect an amphibian host by killing or inhibiting Bd have shown promise as an effective chytridiomycosis control strategy. The North American bullfrog (Lithobates catesbeianus) is a common carrier of Bd and harbours a diverse skin microbiota that includes lactic acid bacteria (LAB), a microbial group containing species classified as safe and conferring host benefits. We investigated beneficial/probiotic properties: anti-Bd activity, and adhesion and colonisation characteristics (hydrophobicity, biofilm formation and exopolysaccharide-EPS production) in two confirmed LAB (cLAB-Enterococcus gallinarum CRL 1826, Lactococcus garvieae CRL 1828) and 60 presumptive LAB (pLAB) [together named as LABs] isolated from bullfrog skin.We challenged LABs against eight genetically diverse Bd isolates and found that 32% of the LABs inhibited at least one Bd isolate with varying rates of inhibition. Thus, we established a score of sensitivity from highest (BdGPL AVS7) to lowest (BdGPL C2A) for the studied Bd isolates. We further reveal key factors underlying host adhesion and colonisation of LABs. Specifically, 90.3% of LABs exhibited hydrophilic properties that may promote adhesion to the cutaneous mucus, with the remaining isolates (9.7%) being hydrophobic in nature with a surface polarity compatible with colonisation of acidic, basic or both substrate types. We also found that 59.7% of LABs showed EPS synthesis and 66.1% produced biofilm at different levels: 21% weak, 29% moderate, and 16.1% strong. Together all these properties enhance colonisation of the host surface (mucus or epithelial cells) and may confer protective benefits against Bd through competitive exclusion. Correspondence analysis indicated that biofilm synthesis was LABs specific with high aggregating bacteria correlating with strong biofilm producers, and EPS producers being correlated to negative biofilm producing LABs. We performed Random Amplified Polymorphic DNA (RAPD)-PCR analysis and demonstrated a higher degree of genetic diversity among rod-shaped pLAB than cocci. Based on the LAB genetic analysis and specific probiotic selection criteria that involve beneficial properties, we sequenced 16 pLAB which were identified as Pediococcus pentosaceus, Enterococcus thailandicus, Lactobacillus pentosus/L. plantarum, L. brevis, and L. curvatus. Compatibility assays performed with cLAB and the 16 species described above indicate that all tested LAB can be included in a mixed probiotic formula. Based on our analyses, we suggest that E. gallinarum CRL 1826, L. garvieae CRL 1828, and P. pentosaceus 15 and 18B represent optimal probiotic candidates for Bd control and mitigation.Fil: Niederle, María Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Bosch, Jaime. Consejo Superior de Investigaciones Científicas; España. Universidad de Oviedo; EspañaFil: Ale, Cesar Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Nader, Maria Elena Fatima. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Aristimuño Ficoseco, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Toledo, Luis Felipe. Universidade Estadual de Campinas; BrasilFil: Valenzuela-Sánchez, Andrés. Universidad Andrés Bello; Chile. Universidad Austral de Chile; ChileFil: Soto-azat, Claudio. Universidad Andrés Bello; ChileFil: Pasteris, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentin

Sugar-glycerol cofermentations by lactobacillus hilgardii isolated from wine

Glycerol catabolism was studied in Lactobacillus hilgardii X1B from wine, growing on glycerol and limiting glucose or fructose concentrations in anaerobiosis and microaerophilia. Glycerol consumption occurred simultaneously with sugar use, and it was higher with fructose as a cofermenting sugar in microaerophilia. Enzymatic activities of the glycerol kinase and glycerol dehydratase pathways were detected in both incubation conditions. In anaerobiosis, the main products were lactate, acetate, ethanol, and the intermediary product of the glycerol dehydratase pathway, 3- hydroxypropionaldehyde. However, in microaerophilia, 1,3-propanediol was also detected. In anaerobic glucose + glycerol and fructose + glycerol cultures as in microaerophilic glucose + glycerol cultures, glycerol was degraded mainly through the reductive pathway. However, when L. hilgardii X1B was grown on fructose + glycerol cultures in microaerophilia, glycerol dissimilation occurred mainly via the glycerol kinase way. According to these results, L. hilgardii X1B can degrade glycerol by producing 3-hydroxypropionaldehyde and acetic acid, both undesirable products for wine sensorial quality. © 2009 American Chemical Society.Fil: Pasteris, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Strasser de Saad, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Microbiological and histological studies of farmed-bullfrog (Rana catesbeiana) tissues displaying red-leg syndrome

Rana catesbeiana is one of the delicacies of international gastronomy. Farming operations often lead to an increased risk of diseases and mortality. The present work addresses microbiological and histological studies in R. catesbeiana with red-leg syndrome (RLS), infection that causes significant economic losses in hatcheries. Partial phenotypical identification demonstrated that the microbial populations isolated from the skin of fattening phase animals and freshwater samples during the autumn (June) are grouped into the following taxa: Lactobacillus spp, Pediococcus spp, Micrococcus spp, Enterococcus faecalis, Ent. faecium and Enterobacteriaceae (Enterobacter spp and Proteus vulgaris). Microbial infection on target organs (liver/spleen) and blood showed the presence of Pr. vulgaris, Staphylococcus aureus and Enterococcus strains. Histological studies of skin ulcerations showed epithelial necrosis, diskeratosis, apoptosis and espongiosis. No sporangia associated with chitridiomycosis were observed. The dermis presented oedema, dilated vascular light, fibrin-leucocytic exudates and distortion of serous and granular glands. The liver showed centrolobullar necrosis and a decrease in melanin containing cells. The spleen presented wide areas of septic infarct. This paper reports the presence of lactic acid bacteria and other genera in the skin and freshwater from farmed R. catesbeiana during the autumn and a correlation between microbial infection and structural changes in tissues of bullfrogs with RLS. The severity of the structural changes is related to the level of microbial infection in the target organs and could be sustained by the isolation of Pr. vulgaris and other pathogens.Fil: Pasteris, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Bühler, M. I.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Nader, Maria Elena Fatima. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; Argentin

Estudio de la microbiota urogenital de cachorras y cerdas preñadas mediante PCR-DGGE

La salud del tracto urogenital (TUG) es requisito para la óptima performance de cerdas y sus camadas para garantizar la rentabilidad en producción porcina. La homeostasis del tracto está condicionada por su microbiota residente que, en su interacción con el hospedador, influye en la fertilidad de las hembras y en la colonización temprana de las mucosas del lechón recién nacido. Objetivo: evaluar la microbiota urogenital en: cachorras (CV) y cerdas preñadas por servicio natural (SN) e inseminación artificial (IA). Metodología: se tomaron muestras por raspado de las mucosas de uretra (U) y vagina (V); las que fueron recibidas en SF estéril y refrigeradas hasta su procesamiento (extracción del ADN total y amplificación de la región V3 del gen 16S ARNr). Los productos amplificados se resolvieron por DGGE (gel de poliacrilamida 8%; gradiente 35-60 de urea?formamida). Los perfiles de banda obtenidos se analizaron (software FINGERPRINTING II) y se generaron clústeres según % de similaridad. En V: la mayor similaridad se observó entre los perfiles de CV y SN (52 y 55%); clústeres con similaridad ≥35% se conformaron con muestras de SN & IA o exclusivamente muestras de CV. En U: 2 clústeres de similaridad >50% agruparon la mayoría de las muestras de SN (50-64%) y de IA (56-92%). Los perfiles de CV no se agruparon entre sí, sino que lo hicieron con muestras de cerdas preñadas por SN (similaridad ≥46%) y por IA (similaridad ≥36%). Bandas representativas se amplificaron, secuenciaron, y compararon con 2 bases de datos (BLAST, RDP); en todos los casos fueron asignadas al phylum Firmicutes. Se identificaron en V de CV: Lactobacillus graminis, Streptococcus suis, S. hyovaginali y Bacillus psychrosaccharolyticus. En SN: éste último, además de S. constellatus, L. fuchuensis y Staphylococcus capitis; en IA: Enterococcus durans/faecium, Anoxybacillus kestanbolensis, Staphylococcus epidermidis/caprae y S. equorum/haemolyticus. En U de CV: L. fuchuensis/sakei/curvatus, S. gallolyticus, y Clostridiales no cultivables; en SN solo se identificó L. fuchuensis; así como Clostridium beijerinckii en el grupo de IA.Conclusión: la microbiota en U de CV y cerdas preñadas (SN e IA) parece ser menos variable que la de V en los mismos grupos de hembras.Diferencias en la estructura poblacional pueden adjudicarse a protocolos del manejo reproductivo, por ejemplo el tipo de servicio utilizado para conseguir la preñez de las cerdas.Fil: Torres Luque, Andrea. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Martín, Alejandro Alberto. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Pasteris, Sergio Enrique. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Otero, María Claudia. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaIV Reunión conjunta de sociedades de biología de la República ArgentinaVirtualArgentinaSociedad Argentina de BiologíaSociedad de Biología de RosarioSociedad Chilena de Reproducción y Desarroll

Fermentation Performance of Selected Microorganisms in Malbec Musts under Two Different Wine Making Conditions

This work evaluates the fermentation performance of simultaneous cultures of selected indigenous Saccharomyces cerevisiae mc2, Kloeckera apiculata mF and Oenococcus oeni X2L in Malbec musts. Fermentations (3 l) were carried out at the pilot plant under two conditions: 1-initial pH 5.5, 60.24 mg/l SO2, 26°C) and 2-initial pH 3.8, 125 mg/l SO2, 28°C), using different culture combinations and S.cerevisiae IOC 18-2007 as control. The final wine densities were 0.992-0.997 g/l (10 days). Microorganisms grew in all conditions. Yeasts prevailed, especially S. cerevisiae (108 CFU/ml) while O. oeni reached 107 CFU/ml. Total reducing sugars consumption was >80% and full malate consumption was observed in all musts inoculated with O. oeni. Ethanol formation corresponded to Malbec variety (310-342 mM), while total acidity did not exceed organoleptic quality limit (4.6-6.49 g/l). Glycerol production was ~84.3-95.1 mM. Among tested esters, ethyl acetate/2-phenyl ethyl acetate showed highest concentration. The sensoryanalysis showed the highest scores for visual descriptors (fluency, color intensity and tonality), olfactory intensity, taste descriptors and general harmony. Thus, we propose an inoculation condition using a mixed yeasts-O.oeni culture and an optimal statistical point to improve microbial performance to obtain quality Malbec wines enhancing body and sensorial properties.Fil: Ale, Cesar Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Morata, Vilma Ines. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Aplicadas a la Industria; ArgentinaFil: Carrión Cervantes, Raúl Orlando. Universidad Nacional de Cuyo. Facultad de Ciencias Aplicadas a la Industria; ArgentinaFil: Pasteris, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

Characterization of a bacteriocin produced by Lactococcus lactis subsp. lactis CRL 1584 isolated from a Lithobates catesbeianus hatchery

Lactococcus lactis CRL 1584 isolated from a Lithobates catesbeianus hatchery inhibits the growth of Citrobacter freundii (a bullfrog pathogen) and Listeria monocytogenes by a synergistic effect between lactic acid, hydrogen peroxide and a bacteriocin-like molecule. The chemical characterization of the bacteriocin in cell-free supernatants indicates that it has a proteinaceous nature. Hexadecane and ethyl acetate did not modify the bacteriocin activity, while 10 and 20 % (v/v) chloroform decreased the activity by 29 and 43 %, respectively. The antimicrobial peptide was heat stable since 85 % of residual activity was detected when neutralized supernatants were heated at 80 °C for 30 min. Moreover, no bacteriocin inactivation was observed when supernatants were kept at -20 °C for 3 months. The synthesis of the bacteriocin was associated with bacterial growth, highest production (2,100 AU/ml) being detected at the end of the exponential growth phase. At pH ranges of 5-6.5 and 5.0-5.5 the inhibitory molecule was stable when stored for 2 days at 4 and 25 °C, respectively. Moreover, it had a bactericidal effect on L. monocytogenes and the ultrastructural studies of pathogenic cells revealed clumping of the cytoplasmic material, increased periplasmic space and cell wall modifications. The deduced amino acid sequence of the bacteriocin was identical to nisin Z and the genetic determinants for its production are harbored in the chromosome. These results, described for the first time in L. lactis from a bullfrog hatchery, will increase knowledge of the bacteriocin under study with a view to its potential inclusion in probiotics for raniculture or biopreservatives.Fil: Pasteris, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; ArgentinaFil: Vera Pingitore, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; ArgentinaFil: Ale, Cesar Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; ArgentinaFil: Nader, Maria Elena Fatima. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; Argentin

Survival and beneficial properties of lactic acid bacteria from raniculture subjected to freeze-drying and storage

Aim: To evaluate the effect of freeze-drying and storage conditions on the viability and beneficial properties of lactic acid bacteria (LAB) for raniculture. Methods and Results: Lactococcus lactis CRL 1584, L. lactis CRL 1827, Lactococcus garvieae CRL 1828 and Lactobacillus plantarum CRL 1606 viability under different conditions was studied. 10% lactose and 5% skim milk + 5%lactose were excellent lyoprotectants, but 5% skim milk + 5% lactose and whey protein concentrated (WPC) or WPC + sugars were the lower cost lyoprotective options. The effect of temperature depended on both lyoprotectants and storage time. Thus, for Lactococcus, skim milk, skim milk + sucrose and WPC + sucrose were selected for lyophilization and storage at 4°C and skim milk + lactose for 25°C. For Lact. plantarum CRL 1606, the best lyoprotectants for lyophilization and storage at 4°C were milk + sugars and WPS + sucrose and, at 25°C, skim milk + sucrose. Conclusions: Lactic acid bacteria viability after freeze-drying was strain specific and depended on the lyoprotectant used. Highest viability was obtained when stored at 4°C, and the beneficial properties remained stable for 18 months independently of storage temperature. Significance and Impact of the Study: The studies reported for the first time in this work are of primary interest to obtain dried bacteria to be included in beneficial products for raniculture.Fil: Montel Mendoza, María Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Pasteris, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Otero, María Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Nader, Maria Elena Fatima. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin