Construction and Experimental Validation of a Homemade Stirred Tank Bioreactor for Lab-scale Submerged Fermentations

Abstract

Small-scale bioreactors are widely used for experimentation in microbiological laboratories. Currently, the price of these systems is in the order of € 20 000, which obstructs its acquisition. A homemade stirred tank system, with easily available and inexpensive resources, was designed and assembled so that meets the essential requirements  for the establishment of microbial fermentation processes on a small-scale.  In this regard, the sterility of the system was checked by applying sterility controls during 24 h of continuous operation under real conditions of handling, including three samplings.  The oxygen transfer coefficient (kla) was determined  by the sulfite method, under different aeration-agitation conditions, yielding  values of 0, 058 s-1 and 0, 033 s-1  under 0, 67 L·min-1 of air flow rate and stirring rates of 850 min-1 and 650 min-1, respectively, which result usually sufficient for optimal microbial growth. The bioreactor exhibited a satisfactory mixing performance, which is expressed by its ability to maintain the temporal stability of the concentration of an insoluble, high density and finely divided solid  (BaSO4).  These results show the practical potentialities of this homemade bioreactor to the study of microbial fermentation at lab -scale level.