Survival of Weissella confusa and Lactobacillus paracasei strains in fermented milks under cold storage and after freeze-drying

The technological properties of two Lactobacillus paracasei (UI014 and UI022) and two Weissella confusa (UI006 and UI007) strains were studied in order to ascertain their suitability to be used in the formulation of probiotic fermented milks. All strains were able to grow in milk increasing their counts for more than 2 logarithmic units. Additionally, L. paracasei strains were able to acidify and coagulate the milk which indicates that they can be employed as starter cultures. However, W. confusa strains can only be used as adjunct cultures since their acidification rate was very low. The viability of most strains declined slowly during the cold storage of the dairy product and after 4 weeks, their counts remained approximately 107 cfu/ml. Thus, the shelf life of these dairy products is long enough to ensure the intake of viable cells that could promote health benefits. Finally, the four strains studied presented high survival after the freeze-drying process using skim milk as cryo-protectant. Thus this technology can be employed to supply these strains to the dairy industries to be used as starter or adjunct cultures for the formulation of probiotic foods.This work was financed by FEDER funds (European Union) and the Spanish Plan Nacional de I+D+i through the project AGL2006-03336 and AGL2007-62736.Peer Reviewe

Optimization of Probiotic Lactobacilli Production for In-Feed Supplementation to Feedlot Cattle

The selection of probiotic bacteria based on their beneficial characteristics does not necessarily mean they can be later scaled up and used for technological applications and formula design. Three probiotic strains—Lactobacillus acidophilus CRL2074, Limosilactobacillus fermentum CRL2085, and Limosolactobacillus mucosae CRL2069, originally isolated from feedlot cattle feces—have demonstrated beneficial characteristics when used as in-feed probiotics. Therefore, the current study was conducted to develop a low-cost culture medium to optimize growth conditions to enhance biomass production. The study also sought to identify appropriate cryoprotective agents to sustain high functional cell numbers after freeze drying. A central composite design was applied to determine the optimal medium composition. This yielded a simplified, low-cost effective medium containing 3% molasses and industrial yeast extracts (0.5 to 2.5%) as carbon and nitrogen sources, which were added to a basal medium for each strain. Established production conditions at 37 °C, without agitation, and pH-controlled for the CRL2085 and CRL2069 strains, and free pH for the CRL2074 strain, allowed us to obtain biomass yields of 12.95, 18.20, and 12.25 g, respectively, at 24-h incubation, compared with the MRS medium. In addition, the cryoprotective effect of the selected agents was demonstrated to be strain-dependent. Thus, the highest viability (109–1010 CFU/g), stability during 30-d storage, and survival rate (88–99%) were achieved when 10% MSG (monosodium glutamate), sucrose + fructose + trehalose + WPC (whey protein concentrate) + 10% MSG, and 1.2% WPC + 10% trehalose, were used for freeze drying CRL2074, CRL2085, and CRL2069, respectively. Moreover, the probiotic strains retained their probiotic functionality when hydrophobic characteristics were evaluated. These results highlight the need to perform strain-specific evaluation of the critical factors involved in the large-scale production of probiotic lactobacilli to sustain viability and stability after the freeze drying and storage processes

Identification, characterization and selection of autochthonous lactic acid bacteria as probiotic for feedlot cattle

Livestock microbiota is becoming a focus of interest for veterinaries, animal nutritionists and microbiologists in view to select beneficial bacteria with impact in health and animal productivity. As resident adapted microorganisms, lactic acid bacteria (LAB) were isolated, identified and characterized from the homologous host to promote their permanence/efficiency acting as additives in feedlot cattle feeding. Cultivable LAB numbers from cattle feces (CF), pens soil (PS) and feed rations (FR) ranged from 5 to 6 log CFU/g during feedlot permanence. Isolates (500) were identified by (GTG)5-PCR and sequence analysis of 16S rRNA, being represented by Enterococcus, Lactobacillus, Leuconostoc, Pediococcus and Weissella genera and 20 different species. Genetic mapping showed that predominant LAB species in CF and PS samples were Lactobacillus (Lb) mucosae (34%), Enterococcus (E) hirae (26%) and E. faecium-durans (20%), while in FR E. faecium-durans (46%), Pediococcus (P). pentosaceous, P. acidilactici (17%) and Lb. acidophilus (11%) were mainly isolated. Surface characterization showed most of LAB as high hydrophilic, however several strains from CF and PS revealed strong hydrophobic and auto-aggregative character with a positive correlation between both superficial properties. Adhesion to polystyrene displayed variable biofilm formation patterns for Enterococcus and Lactobacillus strains depending on the presence of Tween in MRS medium. When antagonistic activity of isolated LAB against bovine relevant pathogens was evaluated, organic acids and hydrogen peroxide production were mostly responsible for inhibition; bacteriocin production was shown only by a Lb. mucosae strain. In addition, tolerance to acid and bile salts showed lactobacilli to withstand GIT conditions, while enterococci were more sensitive to low acid environment. On these bases, several Lactobacillus strains may be selected to explore their potential use as direct fed bacteria in feedlot cattle.Fil: Maldonado, Natalia Cecilia. 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: Mansilla, Flavia Ivana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Melian, Constanza Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Hebert, Elvira Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Vignolo, Graciela Margarita. 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