Towards the continuous production of bacterial metabolites in microfluidic environment

In the present work, a continuous microreactor was designed to study the effect of miniaturization on bioreactors for the production of invertase from S. cerevisiae MM01 in a microfluidic environment. In order to simplify the analysis and considering typical production strategies at laboratory scale, 250 ml baffled flasks and a 2.5 l batch bioreactor were used as bench-scale models for the perfusion microreactor. In order to improve invertase production, the effect of different compounds in the culture media such as carbon source, nitrogen source (organic and inorganic), metal ion, polyether, amino acid and buffer on invertase production and cell growth were screened at bench-scale before scaling-down the process. Maximum invertase activity for baffled flask reactor was registered after 32 hours of process time (1.40 U/ml), immediately before stationary phase, in the non-buffered optimized medium (20 g/l sucrose, 20 g/l yeast extract and 7.5 g/l bacto peptone) at 30 0C, 200 rpm and with an initial pH of 6.0. After microfabrication the optimized medium was tested for dilution factors of 1, 10, 100 and 1000. Maximum invertase activity was registered after perfusion of the most diluted medium for 54 hours (7.94 U/ml) at pH 6.0 and 30 0C.