Modeling solid-to-solid biocatalysis: integration of six consecutive steps.
A quantitative model for the conversion of a solid-substrate salt to a solid-product salt in a batch bioreactor seeded with product crystals is presented. The overall process consists of six serial steps (with dissolution and crystallization each in themselves complex multistep processes): solid-salt dissolution, salt dissociation into an ionic substrate and a counter-ion, bioconversion accompanied by biocatalyst inactivation, complexation of the ionic product with the counter-ion, and salt crystal growth. In the model, the consecutive steps are integrated, including biocatalyst inactivation and assuming that salt dissociation and complexation of ions are at equilibrium. Model parameters were determined previously in separate independent experiments. To validate the model, either dissolved or solid Ca-maleate was converted to solid Ca-D-malate by permeabilized Pseudomonas pseudoalcaligenes in a batch bioreactor seeded with Ca-D-malate crystals. The model very well predicted the concentrations of all components in the liquid phase (Ca-maleate, Ca(2+), maleate(2-), D-malate(2-), and Ca-D-malate) and the amounts of the solid phases (Ca-maleate. H(2)O and Ca-D-malate. 3H(2)O), especially when high initial amounts of Ca-maleate. H(2)O and Ca-D-malate. 3H(2)O were present.
Wageningen University, Food and Bioprocess Engineering Group, Department of Food Technology and Nutritional Sciences, Biotechnion/Dreijencomplex, P.O. Box 8129/6700 EV Wageningen, The Netherlands.MARCO.MICHIELSEN@ALGEMEEN.PK.WAU.NL
M J
MJ
Michielsen
C
C
Frielink
R H
RH
Wijffels
J
J
Tramper
H H
HH
Beeftink
D019149:Bioreactors; D001709:Biotechnology / Q000379:methods*; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis; D003198:Computer Simulation; D003460:Crystallization; D007700:Kinetics; D008298:Maleates / Q000737:chemistry / Q000378:metabolism; D010539:Permeability; D011480:Protease Inhibitors / Q000737:chemistry / Q000378:metabolism; D011549:Pseudomonas / Q000378:metabolism; D012492:Salts / Q000737:chemistry / Q000378:metabolism; D014105:Tosyl Compounds / Q000737:chemistry / Q000378:metabolism
D008298:Maleates; D011480:Protease Inhibitors; D012492:Salts; D014105:Tosyl Compounds; C003614:4-toluenesulfonyl fluoride; C030272:maleic acid; D002118:Calcium