Product and by-product distributions in glutamic acid fermentation by Brevibacterium flavum: effects of the oxygen tansfer

摘要

Production of L-glutamic acid (GA) was accomplished by using Brevibacterium flavum (DSM 20411) in 3.5 dm~3 laboratory scale bioreactors at 30 deg C, initial pH 7.2, penicillin ratio 10 000 U g~(-1) DW, agitation rate 150-500 min`(-1), and air flow rate 0.1-0.2 vvm. Cell and GA concentrations and concentrations of other amino acids and organic acids were measured throughout batch fermentations. By-products varied in number and concentration depending on the amount of oxygen supplied to the broth. Very low oxyge transfer rate favoured pyruvic acid and lacitic acid production; while at higher oxygen transfer levels #alpha#-ketoglutaric acid and succinic acid were favoured. The 0.1 vvm and 250 min~(-1) conditions were optimum for maximum GA production and selectivity.