Abstract Background: This work aimed to explore the action of natural prodigiosin on both bacterial organisms and Trypanosoma cruzi cells. Methods: Natural prodigiosin pigment was extracted and purified from cultures of Serratia marcescens. Two media, peanut broth and peptone glycerol broth, both recommended in the literature for prodigiosin production, were compared. The prodigiosin obtained was employed to explore its antimicrobial properties against both bacteria and Trypanosoma cruzi cells. Results: Peanut broth yielded four times more prodigiosin. The prodigiosin showed remarkable activity (minimal inhibitory concentrations in the range of 2-8 µM for bacteria and half maximal inhibitory concentration of 0.6 µM for Trypanosoma cruzi). In fact, the prodigiosin concentration required to inhibit parasite growth was as low as 0.25 mg/l versus 4.9 mg/l of benznidazole required. Furthermore, atomic force microscopy revealed marked morphological alterations in treated epimastigote forms, although no pore-formation activity was detected in protein-free environments. Conclusions: This work demonstrates the potential usefulness of prodigiosin against some gram-positive and gram-negative bacteria and Trypanosoma cruzi although further studies must be done in order to assess its value as a candidate molecule.

In this article the authors deal with the problem of the didactic restructuring of the university teachers and its specific features, and more particularly in the domains of Mathematics and Experimental Sciences. The REUBE strategy is based on the gathering of precise evidences about the dysfunction that can be observed in a specific teachers or a group of teachers' teaching-learning process. Simultaneously with the gathering of evidences, and together with the teacher, the gathered data during a six-month course are to be analyzed and evaluated and then a specifc plan of intervention can be proposed so it can be put into practice and evaluated during the following courses. After laying the foundations for the need of new strategies, the authors describe the REUBE proposal and give examples of its frst application in four domains of university action.

Se aborda la problemática de la renovación didáctica de los docentes universitarios y las características específicas que comporta, en particular en las áreas de matemáticas y ciencias experimentales. La estrategia REUBE (Renovación de la Enseñanza Universitaria Basada en Evidencias) se basa en la recolección de evidencias puntuales sobre disfunciones observadas en el proceso de enseñanza-aprendizaje de un profesor o grupo de profesores concretos. Simultáneamente a la recolección de evidencias, y conjuntamente con el docente, se analizan y evalúan los datos recopilados a lo largo de un semestre y se propone un plan de intervención específico que se implementará y evaluará en semestres sucesivos. Tras sentar las bases para la necesidad de nuevas estrategias, se describe la propuesta REUBE y se ejemplifica su aplicación inicial en cuatro ámbitos de actuación universitarios.