ONLINE MONITORING OF PENICILLIN-V DURING PENICILLIN FERMENTATIONS - A COMPARISON OF 2 DIFFERENT METHODS BASED ON FLOW-INJECTION ANALYSIS

Two different flow-injection analysis (FIA) methods used for on-line monitoring of penicillin V during fed-batch penicillin fermentations are compared. The fermentations are carried out using a high yielding strain of Penicillium chrysogenum and both analyzers are used continuously for on-line monitoring during 200 h. Both methods are based on a reaction catalyzed by beta-lactamase, which converts penicillin V to penicilloic acid. In analyzer 1 the sample is injected into a buffer stream and carried to a stirred measurement cell containing an enzyme electrode. The enzyme electrode consists of beta-lactamase immobilized onto a sensitive pH glass electrode with a very low response time. No predilution of the sample is required in this analyzer. In analyzer 2 the sample is injected into an enzyme reactor containing immobilized beta-lactamase. The formed penicilloic acid is detected by decolorization of an iodine-starch complex. By means of a second injection valve it is possible to have the sample by-pass the enzyme reactor and instead pass a dummy reactor in which no beta-lactamase is immobilized. Thereby both the concentration of penicillin and penicilloic acid can be measured. On-line dilution of the sample is ensured by a gradient technique. Experimental tal results from on-line monitoring of penicillin V using the two methods are presented. The large amount of precise measurements enables a very good resolution of the penicillin production; something of extreme value for verification of mathematical models describing the fermentation kinetics.