KINETIC STUDY AND MATHEMATICAL MODELLING OF GROWTH OF ARTHROBACTER OXYDANS CELLS COVALENTLY IMMOBILIZED ON CELLULOSE GRANULES

Abstract

The kinetics of covalently immobilized cells' growth in comparison with that of free cells was studied experimentally and numerically. Cells of Arthrobacter Oxydans were covalently immobilized to regenerated and partially deacetylated acetylcellulose granules consecutively activated with sodium periodate, urea and formaldehyde. The comparison of the data obtained showed that free and immobilized cells have the typical three phases of growth. The initial phase of free cells lasted about 10 hours and for immobilized ones - not more then 5 hours. The second exponential phase showed much more significant difference for both types of cells. The curve for immobilized cells is steeper than that of free ones and attains twice faster the third phase. The glucose utilization by immobilized cells was completed about the 15th hour, for the free cells - about 25th hour. The reproducibility of the data was quite satisfactory (mean error 7.42%). A mathematical model was used to describe and analyse the effect of the different mass transfer and reaction kinetic parameters. It shows that replication of immobilized cells is a complex process including mother cells and the new born ones. The application of the results of this study could be concerned with the use of the immobilized cells as a permanent source of free ones. They are viable and possess a long lasting capacity for urea transformation.