초록
<P>This paper hinged on the combination effect of two different neutralizing agents Ca(OH)2 and NH4OH on the production of L-lactic acid by Lactobacillus paracasei. Present study quantitatively indicated that environmental osmotic pressure (844-1,772?mOsm/kg) exerted minor influence on L-lactic acid production, but a critical level fell on approximately 3,000?mOsm/kg which restricted L-lactic acid production significantly. Once osmotic pressure exceeded 3,600?mOsm/kg, L-lactic acid production ran aground. A new and efficient neutralizing agent-adding strategy was established in this study to procure 2.21-fold enhancement (5.94?g/l/h) relative to previous productivity of L-lactic acid with NH4OH as neutralizing agent via batch cultivation. It was, therefore, speculated that inhibition effect in the late phase of the fermentation might be in large part attributed to the dramatic increase of environmental osmotic stress, other than cumulative effect of lactate concentration itself.</P>