Calidad microbiológica del chorizo crudo expendido en el Gran Área Metropolitana de Costa Rica

Introducción. En Latinoamérica, los reportes sobre la calidad microbiológica del chorizo crudo son limitados, sin embargo, es un producto de amplio consumo y de tradición. Objetivo. Conocer la estabilidad microbiológica del chorizo crudo en el Gran Área Metropolitana (GAM) de Costa Rica. Materiales y métodos. Entre enero y agosto de 2019, se realizaron recuentos de indicadores de vida útil y de contaminación, así como la detección de tres patógenos (Salmonella spp., Listeria monocytogenes y Clostridium perfringens) en cincuenta muestras de chorizo crudo obtenidas de carnicerías del Gran Área Metropolitana de Costa Rica. Resultados. De las cincuenta muestras analizadas se encontró que solo una era consumible, según los parámetros generales de recuento bacteriano (recuento total aerobio mesófilo [TAM], hongos y levaduras [HYL] y bacterias ácido-lácticas [BAL]) y que la principal causa de deterioro del producto incluye una combinación de BAL y HYL. Además, los recuentos de coliformes totales variaron entre 105 y 106 UFC/g. Desde el punto de vista de inocuidad, se aisló Salmonella spp. en el 16 % de las muestras, Listeria monocytogenes en el 10 % y Clostridium perfringens se encontró en una única muestra con un recuento de 5,00x101 UFC/g. Conclusión. Productos sin procesamiento térmico como el chorizo crudo expendido en el GAM de Costa Rica, son productos muy susceptibles al deterioro, que presentan altos niveles de contaminación y que podrían comportarse como vehículo de patógenos; por ello, se recomienda mejorar las prácticas de manufactura para prolongar la vida útil y garantizar la seguridad del consumidor

First isolation report of Arcobacter cryaerophilus from a human diarrhea sample in Costa Rica

Arcobacter cryaerophilus is an emerging enteropathogen and potential zoonotic agent transmitted by food and water. In Costa Rica, this bacterium has not been associated with cases of human gastroenteritis, even though it has been isolated from farm animals, especially poultry. This paper reports the first isolation of A. cryaerophilus from a human case of bloody watery diarrhea and the virulence genes associated with this isolate

Potential of New Bacterial Strains for a Multiproduct Bioprocess Application: A Case Study Using Isolates of Lactic Acid Bacteria from Pineapple Silage of Costa Rican Agro-Industrial Residues

Lactic acid bacteria (LAB) with potential for the development of multi-product processes are necessary for the valorization of side streams obtained during the biotechnological production of lactic acid (LA). In this study, 14 LAB strains isolated from pineapple agro-industrial residues in Costa Rica were cultivated in microplates, and the six strains with the highest growth were selected for fermentation in microbioreactors to evaluate the production of LA and acetic acid, and the consumption of glucose. Lacticaseibacillus paracasei 6710 and L. paracasei 6714 presented the highest OD600 values (1.600 and 1.602, respectively); however, the highest LA (in g/L) production was observed in L. paracasei 6714 (14.50 ± 0.20) and 6712 (14.67 ± 0.42). L. paracasei 6714 was selected for bioreactor fermentation and reached a maximum OD600 of 6.3062 ± 0.141, with a LA yield of 84.9% and a productivity of 1.06 g L−1 h−1 after 21 h of fermentation. Finally, lipoteichoic acid (LTA) detection from biomass was performed and the antimicrobial activity of the compounds present in the supernatant was studied. LTA was detected from L. paracasei 6714 biomass, and its supernatant caused significant inhibition of foodborne surrogate microorganisms. LAB isolated from pineapple silage have biotechnological potential for multiproduct processes

Assessment of Different Lactic Acid Bacteria Isolated from Agro-Industrial Residues: First Report of the Potential Role of Weissella soli for Lactic Acid Production from Milk Whey

Abstract: The production of lactic acid (LA) through the microbial conversion of agro-industrial residuals is an important process in the biotechnology industry. The growth kinetics of 30 strains of lactic acid bacteria (LAB) isolated from agro-industrial residues were determined and nine strains were selected for microbioreactor fermentation. Lactiplantibacillus pentosus_70-1 (1.662) and L. pentosus_ 19-2 (1.563) showed the highest OD600 values, whereas the highest growth rates were observed for L. pentosus_19-2 (0.267 h−1) and Weissella soli_31 (0.256 h−1). The production of LA and acetic acid (AA), glucose consumption, and metabolic profiles were determined, without finding significant differences in the production of LA; however, W. soli_29 produced the highest amount of LA (20.833 gL−1) and was able to metabolize most of the studied carbohydrates. Based on these results, W. soli_29 was chosen for a 20 h fermentation in a 7 L bioreactor using both standard medium and milk whey supplemented medium. W. soli_29 produced 16.27 gL−1 and 7.21 gL−1 of LA in each of these mediums, respectively. These results show the underlying potential of Weissella strains for biotechnological applications. Additional analysis which should contemplate different agro-industrial residues and other conditions in bioreactors must be carried out.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Centro de Investigación en Enfermedades Tropicales (CIET)UCR::Vicerrectoría de Docencia::Salud::Facultad de MicrobiologíaUCR::Vicerrectoría de Docencia::Ingeniería::Facultad de Ingeniería::Escuela de Ingeniería de BiosistemasUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro Nacional de Ciencia y Tecnología de Alimentos (CITA

Potential of New Bacterial Strains for a Multiproduct Bioprocess Application: A Case Study Using Isolates of Lactic Acid Bacteria from Pineapple Silage of Costa Rican Agro-Industrial Residues

Lactic acid bacteria (LAB) with potential for the development of multi-product processes are necessary for the valorization of side streams obtained during the biotechnological production of lactic acid (LA). In this study, 14 LAB strains isolated from pineapple agro-industrial residues in Costa Rica were cultivated in microplates, and the six strains with the highest growth were selected for fermentation in microbioreactors to evaluate the production of LA and acetic acid, and the consumption of glucose. Lacticaseibacillus paracasei 6710 and L. paracasei 6714 presented the highest OD600 values (1.600 and 1.602, respectively); however, the highest LA (in g/L) production was observed in L. paracasei 6714 (14.50 ± 0.20) and 6712 (14.67 ± 0.42). L. paracasei 6714 was selected for bioreactor fermentation and reached a maximum OD600 of 6.3062 ± 0.141, with a LA yield of 84.9% and a productivity of 1.06 g L−1 h −1 after 21 h of fermentation. Finally, lipoteichoic acid (LTA) detection from biomass was performed and the antimicrobial activity of the compounds present in the supernatant was studied. LTA was detected from L. paracasei 6714 biomass, and its supernatant caused significant inhibition of foodborne surrogate microorganisms. LAB isolated from pineapple silage have biotechnological potential for multiproduct processes.Universidad de Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Centro de Investigación en Enfermedades Tropicales (CIET)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro Nacional de Ciencia y Tecnología de Alimentos (CITA)UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Tecnología de AlimentosUCR::Vicerrectoría de Docencia::Salud::Facultad de Microbiologí

Peptaibol Production and Characterization from Trichoderma asperellum and Their Action as Biofungicide

Peptaibols (Paib), are a class of biologically active peptides isolated from soil, fungi and molds, which have interesting properties as antimicrobial agents. Paib production was optimized in flasks by adding sucrose as a carbon source, 2-aminoisobutyric acid (Aib) as an additive amino acid, and F. oxysporum cell debris as an elicitor. Paib were purified, sequenced and identified by High-performance liquid chromatography (HPLC)coupled to mass spectrometry. Afterward, a Paib extract was obtained from the optimized fermentations. The biological activity of these extracts was evaluated using in vitro and in vivo methods. The extract inhibited the growth of specific plant pathogens, and it showed inhibition rates similar to those from commercially available fungicides. Growth inhibition rates were 92.2, 74.2, 58.4 and 36.2% against Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria alternata and Fusarium oxysporum, respectively. Furthermore, the antifungal activity was tested in tomatoes inoculated with A. alternata, the incidence of the disease in tomatoes treated with the extract was 0%, while the untreated fruit showed a 92.5% incidence of infection Scanning electron microscopy images showed structural differences between the fungi treated with or without Paib. The most visual alterations were sunk and shriveled morphology in spores, while the hyphae appeared to be fractured, rough and dehydrated

Multilocus typing sequences in Lactobacillus casei isolates from pineapple peels silages

Introducción. Lactobacillus casei se caracteriza por adaptarse al medio durante el proceso fermentativo. Objetivo. Caracterizar con tipificación de secuencias multilocus (MTLS), aislamientos de L. casei presentes en ensilados de cáscara de piña con niveles crecientes de urea. Materiales y métodos. Durante 2017 y con un diseño irrestricto al azar se prepararon veinte silos (2 kg). Cada cinco bolsas, se adicionaron 0, 0,5, 1 y 1,5 % de urea (p/p en base fresca). Después de treinta días, se tomó una muestra de cada repetición para realizar análisis bromatológicos. Se analizó materia seca (MS), proteína cruda (PC), carbohidratos no fibrosos, fibra en detergente ácido (FDA), fibra en detergente neutro (FDN), digestibilidad in vitro de la materia seca (DIVMS), hemicelulosa, extracto etéreo (EE), cenizas, nitrógeno amoniacal y pH. Se determinó el recuento de bacterias ácido-lácticas (BAL) para cada uno de los tratamientos. La identificación de las BAL se realizó con la secuencia del ARNr 16S. Los aislamientos de L. casei fueron analizados con MTLS. Resultados. Los cuatro tratamientos evaluados no presentaron diferencias significativas en la MS (12,10 a 12,86%), FDA (31,44 a 32,18 %), FDN (58,46 a 58,56 %), hemicelulosa (26,36 a 27,02 %), EE (2,45 a 2,96 %), cenizas (4,96 a 5,12%), nitrógeno amoniacal (0,45 a 0,49 %) y pH (3,36 a 3,48). No así, en PC (6,94 a 9,12 %) y DIVMS (82,84 a 84,72 %). La adición de urea se asoció a cambios en las poblaciones de BAL (6,56 a 6,90 UFC). Siete aislamientos de L. casei se identificaron y tipificaron con cinco genes distintos. Se encontraron entre dos (polA) y cinco (nrdD, pgm, mutL) alelos; esto permitió identificar un total de seis secuencias tipo (ST) distintas en los aislados de Costa Rica. Conclusión. Los aislamientos de L. casei se encontraron emparentados a bacterias del tracto gastrointestinal en humanos.Introduction. Lactobacillus casei is characterized by adapting to the environment during the fermentation process. Objective. To characterize with multilocus typing sequences (MTLS) isolates of L. casei present in pineapple peel silage with increasing levels of urea. Materials and methods. During 2017 and using an unrestricted random design, twenty silos (2 kg) were prepared. Every five bags, 0, 0.5, 1 and 1.5 % urea (w/w on fresh basis) were added. After thirty days, a sample was taken from each repetition for bromatological analysis. Dry matter (DM), crude protein (PC), non-fibrous carbohydrates, fiber in acid detergent (ADF), fiber in neutral detergent (NDF), in vitro digestibility of dry matter (IVDDM), hemicellulose, ethereal extract (EE), ashes, ammonia nitrogen, and pH. The Lactic Acid Bacteria (LAB) count was determined for each one of the treatments. Identification of LABs was carried out using the 16S rRNA sequence. The isolates of L. casei were analyzed using MTLS. Results. The four evaluated treatments did not present significant differences in DM (12.10 to 12.86 %), ADF (31.44 to 32.18 %), NDF (58.46 to 58.56 %), hemicellulose (26.36 to 27.02 %), EE (2.45 to 2.96 %), ash (4.96 to 5.12 %), ammonia nitrogen (0.45 to 0.49 %) and pH (3.36 at 3.48). Not so, in CP (6.94 to 9.12 %), and IVDDMS (82.84 to 84.72 %). The addition of urea was associated with changes in the BAL populations (6.56 to 6.90 CFU). Seven isolates of L. casei were identified and typed with five different genes. Between two (polA) and five (nrdD, pgm, mutL) alleles were found. This allowed the identification of a total of six different type sequences (ST) in the Costa Rican isolates. Conclusion. The L. casei isolates were found to be related to bacteria from the gastrointestinal tract in humans.Universidad de Costa Rica/[801-B5-505]/UCR/Costa RicaUCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de ZootecniaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro de Investigación en Nutrición Animal (CINA)UCR::Vicerrectoría de Docencia::Salud::Facultad de MicrobiologíaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Centro de Investigación en Enfermedades Tropicales (CIET)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro Nacional de Ciencia y Tecnología de Alimentos (CITA)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro de Investigaciones Agronómicas (CIA)UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Tecnología de AlimentosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biología Celular y Molecular (CIBCM

Multi-Product Lactic Acid Bacteria Fermentations: A Review

Industrial biotechnology is a continuously expanding field focused on the application of microorganisms to produce chemicals using renewable sources as substrates. Currently, an increasing interest in new versatile processes, able to utilize a variety of substrates to obtain diverse products, can be observed. A robust microbial strain is critical in the creation of such processes. Lactic acid bacteria (LAB) are used to produce a wide variety of chemicals with high commercial interest. Lactic acid (LA) is the most predominant industrial product obtained from LAB fermentations, and its production is forecasted to rise as the result of the increasing demand of polylactic acid. Hence, the creation of new ways to revalorize LA production processes is of high interest and could further enhance its economic value. Therefore, this review explores some co-products of LA fermentations, derived from LAB, with special focus on bacteriocins, lipoteichoic acid, and probiotics. Finally, a multi-product process involving LA and the other compounds of interest is proposed

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.