CONSTRUCTION OF INDIVIDUAL BIOREACTORS. HOW TO USE THEM THROUGH PROJECT-BASED LEARNING FOR COMPETENCIES IN DESIGNING, ANALYZING AND INTERPRETING EXPERIMENTS IN LARGE GROUPS OF STUDENTS
The process of cellular respiration and fermentation is one of the essential contents of the study in the programs of cellular biology, which has direct applicability in biotechnology in the field of fermentative processes. Several textbook references tell us extensively with this subject, but only at a theoretical level. Although bioreactor practices are relatively common in the curriculum of faculties, due to the excessive price and fragility of available commercial appliances, a single bioreactor it is usually used for all students, and is have used only at a demonstrative level. In a different way, certain simple assemblies based glass instruments are much more economical and allow for a greater number of devices, but even these systems are not feasible to provide one apparatus pupil ratio, when teaching to large groups. In the present paper, we present the made of a simple 50 ml bioreactor easy to assemble with common laboratory materials (centrifuge tubes). This assembly is inexpensive, resistant and affordable to provide an apparatus to each student, allowing massive experiments in the big groups. Several students’ tests in experimental conditions in his own bioreactor. The students’ works in the following context: they are a part of an R & D team that must optimize the fermentation process of an alcoholic beverage at an industrial level. It is a matter of obtaining a final product with certain parameters required of alcoholic content, residual sugars and time of fermentation. To do this deal, they provided with several industrial strains of yeast, with very different fermentative properties, and a raw material (grape juice, honey, and barley or fruit juices). This project consists the industrial process optimization; therefore, the most important thing is carrying out the pilot tests in a small-scale research laboratory, in its individual 50ml bioreactors. For the first decision-making, which is consider by all members of the group, the whole class decides which conditions will be tested (yeast strains, starting sugars concentration, etc.) and which experimental variables will measure (alcohol content, Rate of CO2 production, pH, etc.). The common work plan is defined, consisting of the conditions that individual students will test in their fermenter, and once collected the data are analyzed and interpreted and decide which are the ideal conditions for the fermentation. Once the procedure is decided, it has recalculated for an industrial and scaled process. To do this, they will use a larger container (10 liter drum) in which they will prepare the alcoholic beverage chosen again. If the optimized conditions from the mass experiment with the individual bioreactors are correct, a product of the required characteristics must be achieve. We believe that the use of our individual bioreactor system greatly increases the motivation and effectiveness of learning, and allows activities within the methodology of Project-Based learning to be very useful for learning outcomes in the design, analysis and interpretation of Experiments in the field of biotechnology and related fields.