3 AUTOMATED FEEDING STRATEGIES OF NATURAL COMPLEX NUTRIENTS UTILIZINGONLINE TURBIDITY VALUES IN FED-BATCH CULTURE - A CASE-STUDY ON THE CULTIVATION OF A MARINE MICROORGANISM

A comparison of three automated feeding strategies was made utilizing on-line turbidity values in fed-batch cultures. Control indices in the se feeding strategies were (i) total cell mass (VX), (ii) total cell m ass (VX) and estimated cell yield on the basis of the total amount of the substrate supplied (Y(x/ins)), and (iii) growth rate (d(VX)/dt). A marine microorganism, Alteromonas putrefaciens, was cultivated by fee ding a solution composed of peptone (220 g/l) and yeast extract (110 g /l). When the automatic feeding strategy (i) was applied, a considerab le amount of peptide accumulated in the later phase, indicating 'overf eeding' of the natural complex nutrients. The improved feeding strateg ies (ii) and (iii) enabled the overfeeding to be avoided, resulting in more effective utilization of the nutrients fed. Overall, the maximum cell concentrations were increased more than 1.5 times, while the tot al amounts of nutrients fed were reduced by a half.