form of a single batch or can be fed in during the culture in a suitable manner basic compounds such as sodium hydroxide potassium hydroxide ammonia or acid compounds such as phosphoric acid or sulfuric acid can be employed in a suitable manner to control the ph antifoams such as fatty acid polyglycol esters can be employed to control the development of foam suitable substances having a selective action e g antibiotics can be added to the medium to maintain the stability of plasmids to maintain aerobic conditions oxygen or oxygen containing gas mixtures such as e g air are introduced into the culture the temperature of the culture is usually 20 u00b0 c to 45 u00b0 c and preferably 25 u00b0 c to 40 u00b0 c culturing is continued until a maximum of l amino acid has formed this target is usually reached within 10 hours to 160 hours the analysis of l amino acids can be carried out by anion exchange chromatography with subsequent ninhydrin derivation as described by spackman et al analytical chemistry 30 1958 1190 or it can take place by reversed phase hplc as described by lindroth et al analytical chemistry 1979 51 1167 1174 the following microorganism has been deposited at the deutsche sammlung fu ar mikroorganismen und zellkulturen dsmz german collection of microorganisms and cell cultures braunschweig germany in accordance with the budapest treaty escherichia coli k 12 dh5 u03b1 pec t18mob2 as dsm 13244 in the accompanying figures the base pair numbers stated are approx values obtained in the.