Effects of immobilization in Ba-alginate on nitrile-dependent oxygen uptake rates of Candida guilliermondi

Dias, Joäo Carlos TeixeiraRezende, Rachel PassosLinardi, Valter Roberto

Yeast cells immobilized by entrapment in Ba-alginate gel were investigated for growth pattern and respiratory activity. The oxygen uptake rates (OUR) of cells entrapped in gels with 4 per cent alginate were 5.2 and 23 per cent lower than the OUR of 2 per cent alginate and free cells, respectively. The mass-transfer resistance offered by the matrix and growth of the entrapped cells determine a gradient of nutrients throughout the gel which is responsible for both a lower specific growth rate of immobilized cells with respect to that of free ones, and a heterogeneous biomass distribution, with progressively increasing cellular density from the inside to the outside of the matrix. Gel-matrix polymer concentration affected the maximum oxygen uptake of immobilized growing yeast cells.