Kinetic and Thermodynamic Characterization of Lysine Production Process in Brevibacterium lactofermentum

Abstract

Detailed kinetic and thermodynamic parameters for lysine production from Brevibacterium lactofermentum are investigated for the first time in this study. Production of the essential amino acid, L-lysine, by B. lactofermentum was assessed in a flask and a continuously stirred tank fermentor (22 L). Maximum lysine production was achieved after 40 h of growth and at 35 °C. The effect of different nitrogen sources such as NH(4)NO(3), (NH(4))(2)SO(4), (NH(4))(2)HPO(4), corn steep liquor, NaNO(3), and urea showed that corn steep liquor gave a better lysine yield. Lysine production was increased when dissolved oxygen was maintained at 50 % saturation. The use of dissolved oxygen was critical for high productivity. This indicates that dissolved oxygen greatly affects L-lysine productivity. Kinetic and thermodynamic parameters during lysine production from molasses and glucose mixture showed that B. lactofermentum efficiently converted the substrate mixture into cell mass and lysine. Kinetic and thermodynamic parameters were significantly higher compared with other microorganisms which may be due to the high metabolic activity of B. lactofermentum. This study will have a significant impact on future strategies for lysine production at industrial scale.