Ultrasound-assisted enzymatic synthesis of galacto-oligosaccharides using native whey with two commercial ß-galactosidases: Aspergillus oryzae and Kluyveromyces var lactis.

Native whey obtained during casein micelle microfiltration was used as a novel source to produce galacto-oligosaccharides (GOS). Since the presence of macromolecules and other interferers reduces biocatalyst performance, this work evaluated the effect of different ultrasound processing conditions on GOS synthesis using concentrated native whey. Ultrasonic intensities (UI) below 11 W/cm2 tended to increase the activity in the enzyme from Aspergillus oryzae for several minutes but accelerated the inactivation in that from Kluyveromyces lactis. At 40 °C, 40 % w/w native whey, 70 % wave amplitude, and 0.6 s/s duty-cycle, a UI of 30 W/cm2 was achieved, and the increased specific enzyme productivity was similar to the values obtained with pure lactose (∼0.136 g GOS/h/mgE). This strategy allows for obtaining a product containing prebiotics with the healthy and functional properties of whey proteins, avoiding the required purification steps used in the production of food-grade lactose.

Creación del primer biorrepositorio nacional de bacterias multirresistentes disponible para el estudio de la resistencia bacteriana en Chile / Creation of the first national biorepository of multi-resistant bacteria available for the study of bacterial resistance in Chile

La disponibilidad de cepas bacteriana para el estudio de la resistencia bacteriana es clave para los avances en la investigación básica y clínica respecto del tema. Existen pocos biorrepositorios o bancos de bacterias con mecanismos de resistencia conocidos, aisladas de infecciones clínicamente significativas. Una revisión de la literatura revela que sólo en los Estados Unidos de América existe un biobanco de aislados resistentes disponibles para estudios. En esta publicación se cuenta cómo se creó el primer biorrepositorio de bacterias resistentes en Chile asociados a la Red de Laboratorios MICROB-R, con la participación de 11 centros distribuidos a lo largo del país, que a la fecha cuenta con más de 3.500 aislados bacterianos estudiados fenotípica y genotípicamente, disponibles para la comunidad científica chilena.

The availability of bacterial strains for the study of bacterial resistance is key to advances in basic and clinical research. There are few biobanks of bacteria with known resistance mechanisms, isolated from clinically significant infections. A review of the literature reveals that only in the United States of America is there a biobank of resistant isolates. This publication shows the creation of the first biorepository of resistant bacteria Chile associated with the MICROB-R Laboratory Network, with the participation of 11 centers distributed throughout the country, which to date has more than 3,500 bacterial isolates studied phenotypically and genotypically, available to the Chilean scientific community.

Prediction of the Limiting Flux and Its Correlation with the Reynolds Number during the Microfiltration of Skim Milk Using an Improved Model.

Limiting flux (JL) determination is a critical issue for membrane processing. This work presents a modified exponential model for JL calculation, based on a previously published version. Our research focused on skim milk microfiltrations. The processing variables studied were the crossflow velocity (CFV), membrane hydraulic diameter (dh), temperature, and concentration factor, totaling 62 experimental runs. Results showed that, by adding a new parameter called minimum transmembrane pressure, the modified model not only improved the fit of the experimental data compared to the former version (R2 > 97.00%), but also revealed the existence of a minimum transmembrane pressure required to obtain flux (J). This result is observed as a small shift to the right on J versus transmembrane pressure curves, and this shift increases with the flow velocity. This fact was reported in other investigations, but so far has gone uninvestigated. The JL predicted values were correlated with the Reynolds number (Re) for each dh tested. Results showed that for a same Re; JL increased as dh decreased; in a wide range of Re within the turbulent regime. Finally, from dimensionless correlations; a unique expression JL = f (Re, dh) was obtained; predicting satisfactorily JL (R2 = 84.11%) for the whole set of experiments.

Seroprevalencia de Toxoplasma gondii en gatos (Felis catus, Linnaeus 1758) residentes en San Carlos, Chile / Seroprevalence of Toxoplasma gondii in Cats (Felis catus, Linnaeus 1758) Living in San Carlos (Chile) / Soroprevalência de Toxoplasma gondii em gatos (Felis catus, Linnaeus 1758) residentes em Sam Carlos, Chile

En Chile existen pocos trabajos referidos a seroprevalencia de toxoplasmosis; por eso, el objetivo del artículo fue determinar su seroprevalencia en felinos de la comuna de San Carlos, mediante la técnica serológica Elisa ImmunoComb® y, al mismo tiempo, ver la asociación con las variables sexo, edad, alimentación y hábitat. Para esto se muestrearon aleatoriamente 60 felinos mayores de dos meses de edad. Los sueros fueron analizados con el kit de Elisa ImmunoComb® Biogal Toxo & Chlamydia, que detecta anticuerpos tipo inmunoglobulina G específicos contra Toxoplasma gondii con una sensibilidad del 92,3 % y una especificidad del 100 %. Con ello se evidenció que 29 individuos fueron positivos (48,3 % de seroprevalencia), que al desglosar según sexo correspondieron a 9 machos y 20 hembras (39,1 y 54 %, respectivamente). Mientras que, según la edad, la seropositividad fue mayor en el grupo adult (76,7 %), seguido de los rangos de mayores de 7 años (50 %) y young (25 %). Con respecto a la alimentación, la seropositividad más alta se obtuvo en aquellos alimentados con dieta mixta por sobre la comercial (60 % vs. 47,2 %). Según la variable hábitat, fueron positivos 16 gatos indoor y 13 outdoor (45,7 y 52%), lo que muestra diferencia estadísticamente significativa solo para la variable edad (p < 0,05). Por último, al relacionar la edad con la seropositividad, se evidenció una correlación negativa (r = -0,3), lo cual indica que a mayor edad de los individuos existió una menor seroprevalencia. Los resultados obtenidos demuestran la presencia de anticuerpos contra Toxoplasma gondii en felinos domésticos.

There are few studies about seroprevalence of toxoplasmosis in Chile; therefore, this article aims to determine seroprevalence in cats in the district of San Carlos, by ELISA Immuno-Comb® serological technique, and, at the same time, to examine association with variables of sex, age, diet, and habitat. To the effect, 60 cats over 2 months old were randomly sampled. Sera were analyzed using the ELISA ImmunoComb® Biogal Toxo & Chlamydia test kit, which detects specific immunoglobulin G-type antibodies against Toxoplasma gondii with a sensitivity of 92.3% and a specificity of 100%. The study evidenced that 29 individuals were positive (48.3% seroprevalence); when broken down by gender this corresponded to 9 males and 20 females (39.1% and 54%, respectively). By age, seropositivity was higher in the "Adult" group (76.7%), followed by groups "Over 7 years" (50%) and "Young" (25%). With respect to diet, higher seropositivity was obtained in animals fed on mixed diet, as opposed to commercial diet (60% vs. 47.2%). By variable habitat, 16 indoor and 13 outdoor cats were positive (45.7% and 52%), showing statistically significant difference only for the variable age (p <0.05). Finally, through relating age with seropositivity, a negative correlation was evidenced (r = -0.3), indicating that older individuals had lower seroprevalence. The results show the presence of antibodies against Toxoplasma gondii in domestic cats.

No Chile existem poucos trabalhos referidos a soroprevalência de toxoplasmose; por isso, o objetivo do artigo foi determinar a sua soroprevalência em felinos da comuna de Sam Carlos, mediante a técnica sorológica ELISA ImmunoComb® e, ao mesmo tempo, ver a associação com as variáveis sexo, idade, alimentação e hábitat. Para isto se amostraram aleatoriamente 60 felinos maiores de 2 meses de idade. Os soros foram analisados com o kit de ELISA ImmunoComb* Biogal Toxo & Chlamydia, que detecta anticorpos tipo imunoglobulina G específicos contra Toxoplasma gondii com uma sensibilidade de 92,3 % e uma especificidade de 100 %. Com isso observou-se que 29 indivíduos foram positivos (48,3 % de soroprevalência), e que ao separar de acordo com sexo corresponderam a 9 machos e 20 fêmeas (39,1 e 54 %, respectivamente). Enquanto que, de acordo à idade, a soro positividade foi maior no grupo Adult (76,7 %), seguido dos rangos de maiores de 7 anos (50 %) e Young (25 %). Em quanto à alimentação, a soro positividade mais alta se obteve naqueles alimentados com dieta mista sobre a comercial (60 % vs. 47,2 %). De acordo com o variável hábitat, foram positivos 16 gatos indoor e 13 outdoor (45,7 e 52%), o que a mostra diferença estatisticamente significativa só para a variável idade (p < 0,05). Por último, ao relacionar a idade com a soro positividade, se evidenciou uma correlação negativa (r = -0,3), o que indica que à maior idade dos indivíduos existiu uma menor soroprevalência. Os resultados obtidos demonstram a presença de anticorpos contra Toxoplasma gondii em felinos domésticos.