Production and properties of a bioemulsifier obtained from a lactic acid bacterium.

In the present work, the production of bioemulsifier (BE) by a lactic acid bacterium (LAB) grown at 25 °C in lactic whey-based media for 24 h was evaluated. Maximum production was detected in a medium containing yeast extract, peptone and lactic whey (LAPLW medium), with a yield of 270 mg L-1. The BE proved to be more innocuous for Caco-2 cells, used as a toxicological indicator, than the non-ionic surfactant Triton X-100. In addition, the microbial product presented higher stability to changes in temperature (37 °C to 100 °C), pH (2-10), and salt concentration (5% and 20%, w/v) than the synthetic surfactant. Regarding emulsifying capacity tested against different hydrophobic substrates (kerosene, motor oil, diesel, sunflower oil, and grape oil), the BE displayed E24 values similar to or even better than those of Triton X-100. Finally, Triton X-100 caused irreversible modifications on the giant unilamellar vesicles (used as model membrane system), promoting the solubilization of the lipid bilayers. Nevertheless, BE induced temporary modifications of the membrane, which is associated with incorporation of the bioproduct in the outer layer. These results demonstrate the role of BE in biological processes, including reversible changes in microbial membranes to enhance the access to hydrophobic substrates.

Deteccion de portadores asintomaticos de quistes hidatidicos: aumento de la especificidad del ensayo immunoenzimatico

Una de las actividades que realizan los programas de control de hidatidosis causada por Echinococcus granulosus en la Republica Argentina es la busqueda de portadores asintomaticos de quistes hidatidicos entre la poblacion general que habita las areas de risco, mediante un ensayo inmunoenzimatico (EIE) con antigeno de liquido hidatidico total (EIE-ALHT) que selecciona los posibles portadores. En base a la experiencia recogida se ha observado que dependiendo de la prevalencia del area, entre el 10 por cento y el 30 por cento de las personas seleccionadas por el EIE con valores de densidad optica (DO * DO + 4S no presentan imagens compatibles con quistes hidatidicos. El proposito del estudio fue mejorar la especificidad de la prueba. Con ese fin, se evaluo la influencia de la modificacion de la oferta antigenica y el efecto de la absorcion de los anticuerpos anti-componentes sericos ovinos y anti-fosforilcolina de los sueros en estudios, 114 sueros no hidatidicos seleccionados por su alto nivel de reacciones cruzadas en EIE-ALHTy 118 sueros hidatidicos se estudiaron frente a 4 fracciones antigenicas de liquido hidatidico ovino. El EIE que empleo la fraccion antigenica S2B conjuntamente con la absorcion previa de los sueros (EIE-S2B/A) fue el sistema que mejor discrimino los sueros hidatidicos de los no hidatidicos

[Detection of asymptomatic carriers of hydatid cysts: specificity increase of the immunoenzyme assay]. / Detección de portadores asintomáticos de quistes hidatídicos: aumento de la especificidad del ensayo inmunoenzimático.

An enzymoimmunoassay (EIE) as a screening test to select potential asymptomatic cyst carriers among the general population of areas under risk is being used in programs for the control of hydatic diseases caused by Echinococcus granulosus in Argentina. The experience obtained up to date, applying this assay in population surveys, indicates that depending on the prevalence in the area 10% to 30% of the individuals selected did not show images compatible with hydatic cysts. The purpose of the present study was to improve the specificity of the test. To this purpose, the influence of the modification of the antigenic availability and the effect of the absorption from the serum samples of antibodies anti-normal ovine sera and anti-phosphorylcholine was evaluated. One hundred and fourteen non hydatic sera selected because of their high cross reactivity in EIE using the whole hydatid antigen (WHA) and 118 hydatid sera, were studied with four fractions of ovine hydatid cyst fluid. The EIE employing the S2B antigenic fraction with previous absorption of the sera (EIE-S2B/A) was the system that discriminated better hydatid sera from non hydatid sera with high levels of cross reactivity. The replacement of the EIE employing WHA by the EIE-S2B/A system, for the active search of asymptomatic cyst carriers in field conditions, is proposed. The four antigenic fractions were analyzed by double diffusion and SDS-PAGE. The S2B fraction revealed a high content of parasitic components of less than 30 Kd which probably includes antigen B and subunits or fragments of antigen 5.