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Abstracts / Journal of Biotec

ai, F.W., Anderson, W.A., Moo-Young, M., 2008. Ethanol fermentation technologiesfrom sugar and starch feedstocks. Biotechnology Advances 26, 89–105.

ayrock, D.P., Ingledew, W.M., 2001. Application of multistage continuous fermenta-tion for production of fuel alcohol by very-high-gravity fermentation technology.Journal of Industrial Microbiology and Technology 27, 87–93.

ones, A.M., Ingledew, W.M., 1994. Fuel alcohol production—assessment of selectedcommercial proteases for very high gravity wheat mash fermentation. Enzymeand Microbial Technology 16, 683–687.

oi:10.1016/j.jbiotec.2008.07.1150

5-YP-004

inetic model for substrate utilization and antibiotic produc-ion using immobilized penicillin G acylase

. RadhaK ∗, R. Lavanya

Anna University, Chennai, India

-mail address: radhavel@yahoo.com (V. RadhaK).

enicilin G acylase is an important enzyme for the industrial pro-uction of 6-aminopenicillanic acid from penicillin G. Studies wereade to predict kinetic behavior of immobilized penicillin G acy-

ase (Luedeking and Piret, 1959), their optimal temperature, pH andeactivation kinetics on polyacrylic beads by using Ludeking piretodel parameter. It was found that the substrate utilization grad-

ally decreases with time as the enzyme activity increases whichesults in the product formation and the substrate concentrationCardoso et al., 1993) was obtained from the Ludeking piret param-ter as 0.266 g cells/g substrate. From the biomass growth curve,he maximum specific growth rate was obtained as 0.588 h−1.Theptimal conditions for the penicillin G acylase activity were foundo be higher at an operating temperature of 45 ◦C and at pH 6.5.herefore, this period was chosen as being suitable for investigat-ng the effects of process conditions on the kinetics of hydrolysisf cephalosporin G by penicillin G acylase rate (Duan and Chen,996). The kinetic parameters were determined as Km = 300 mM,m = 2.5 mM. Activity in the temperature range of 25–45 ◦C washaracterized by an activation energy of 994.9 kJ mol−1 (Erarslannd Kocer, 1991). Beyond this temperature, deactivation is anotherignificant effect and it was characterized by deactivation energyf 1191.4 kJ/mol.

eferences

ardoso, J.P., Cabral, J.M., Fonseca, L.P., 1993. Immobilization studies of an industrialpenicillin acylase preparation on a silica carrier. J. Chem. Technol. Biotechnol. 58(1), 27–37.

uan, G., Chen, J.Y., 1996. Kinetic analysis of the effects of products removal on thehydrolysis of penicillin G by immobilized penicillin acylase. Process Biochem.31, 27–30.

rarslan, A., Kocer, H., 1991. Thermal inactivation kinetics of penicillin G acylaseobtained from a mutant strain of Escherichia coli. Chem. Technol. Biotechnol. 55,79–84.

uedeking, E., Piret, L., 1959. A kinetic study of the lactic acid fermentation batchprocess at controlled pH. J. Biochem. Microbiol. Technol. Eng. 4, 231–241.

oi:10.1016/j.jbiotec.2008.07.1151

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y 136S (2008) S460–S495 S493

5-YP-008

hree-dimensional model of biofilm growth in porous media

.A. Graf von der Schulenburg a,∗, L.F. Gladden a, M.L. Johns a, C.icioreanu b, M.C.M. van Loosdrecht b

Department of Chemical Engineering, University of Cambridge, Pem-roke Street, Cambridge CB2 3RA, UKDepartment of Biotechnology, Delft University of Technology,

ulianalaan 67, 2628 BC, Delft, The Netherlands

-mail address: dawg2@cam.ac.uk (D.A. Graf von der Schulenburg).

variety of one and two-dimensional models of biofilm growthave been developed and reported in the literature. To simulatehe entire complexity of biofilm growth and its spatial hetero-eneity three-dimensional models are necessary. These models areighly complex and so far only three-dimensional models withwo main simplifications have been published. One is the reduc-ion of the interaction between bulk liquid and biofilm to a simplenfinite constant concentration source boundary condition, whichoes not include the coupling of hydrodynamics and mass trans-ort and is only valid in very specific systems, with an unlimitedutrient and oxygen source and no gradients within the bulk liquid.nother simplification often made is the consideration of simpleeometries such as a flat surface. This might be of interests for thetudy of for example biofilm pattern formation, but is often notufficient to model a variety of complex and relevant biofilm sys-ems and applications: e.g. biofilm mediate soil filtration, biofilmmpact on oil recovery, paper manufacturing and food processingperations, membrane biofouling, bioremediation processes andiofilm growth on medical devices. All these systems and appli-ations involve complex geometries such as porous media andonsequently demand the computation of the physics of hydro-ynamics and mass transport for the entire system including theulk liquid. In this study we present the first three-dimensionaliofilm model of biofilm growth in porous media. The lattice Boltz-ann (LB) method is known for its high performance in simulating

ydrodynamics and mass transport in any arbitrary complex geom-try (LIT). The LB model was coupled with an individual basediofilm growth model (IbM) and follows an algorithm similar tohe one shown in the literature by van Loosdrecht et al. (2002).he LB method is used to simulate the flow filed through a porousedia which provides the pressure, shear and velocity field. The

B method further uses the velocity field to simulate the massransport where different chemical species (e.g. nutrient, oxygenr products) are consumed or produced by different bacteria basedn a biofilm concentration map. The resulting species concentra-ion maps are then used by the IbM to simulate the growth, division,eath, detachment (based on shear rate) and shoving of the bacte-ial cells. This provides new resulting biomass concentration mapsnd a new input geometry for the LB simulation. The decoupling ofiofilm growth and mass and momentum transport is possible dueo the different time scales of the two processes being more thanix orders of magnitude apart.

During this study the model is presented and the cases of 2Dnd 3D simulations of biofilm growth in porous media will be com-ared and discussed. A case study will be the clogging of a sand-like

orous media due to biofilm growth and its impact on the velocitynd pressure field.

oi:10.1016/j.jbiotec.2008.07.1152