Development of a Litre-Scale Process for the Production of High-Purity Galactoligosaccharides by Kluyveromyces Lactis
A litre-scale process for the production of high purity GOS by Kluyveromyces lactis(K.lactis)was developed,including catalytic reaction using permeabilized K.lactis cells and purification using non-permeabilized K.lactis cells.In the laboratory reaction stage(25 mL),the specific activity(U/mg)was defined to eliminate the deviation caused by wet cell concentration in different batches.It was found that the con-centration of PBS decreased from 50 to 5 mmol/L,which had no effect on the catalytic production of GOS,but greatly reduced the salt content of GOS product.At the expansion reaction stage(1 L),a new feeding method of substrate was adopted,which shortened the optimum reaction time by 4-fold and eliminated the effect of amplification.The yield of GOS reached 19.15％under the optimum reaction conditions(enzyme dosage 100 U/mL,salt concentration 5 mmol/L,stirring speed 400 r/min)after optimization of stirring speed.At the purification stage,the purity of GOS reached 96.21％under the optimum conditions(carbohydrate concentration 100 g/L,non-permeabilized K.lactis cells concentration 50 g/L)after spray drying.The GOS product is no sugar detected and has the salt content at only 3.79％,which meets the national standard of oligosaccharides.
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