SummaryLaboratory and pilot-plant high-speed bead mills of 0.6 and S liter capacity and consisting of four and five impellers in series, respectively, were used to follow the batch and continuous disruption of bakers' yeast (Sac.c.liurom?c.e.t ccwr,i.sicrc~). The mills are not scaled equivalents. Throughputs ranging from I x m3/sec to 12 x mYsec to 100 x 10P m3/sec for the 5 liter mill were used for continuous disruption studies. Variables studied included the effect of impeller tip speed, temperature, and packed yeast concentration (ranging from IS to 7% by weight packed yeast). Disruption kinetics, as measured by the release of soluble protein, followed a first-order rate equation, the rate constant being a function of impeller tip speed and yeast concentration. For continuous disruption studies the bead mills behaved as a series of continuous stirred-tank reactors, each impeller forming a reactor. In the smaller mill a considerable degree of backflow between the reactors was evident. For certain mixing conditions the maximum amount of releasable protein was dependent on the impeller geometry. construction material, and also the concentration of packed yeast. The relative power efficiencies of the two mills are discussed along with possible criteria for scaling of bead mills. m3/sec for the 0.6 liter mill and from 16 x

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SummaryGlucose isomerase (D-XylOSe ketol-isomerase EC 5.3. I . 5 ) from Bacillus coagu~ans was partially purified and immobilized by adsorption to anion exchangers. The highest activities were obtained when the enzyme was adsorbed to DEAE-cellulose. On immobilization to DEAE-cellulose the measured optimum pH value for enzyme activity shifted from 7.2 to 6.8. There was no appreciable difference between the heat stabilities of soluble and immobilized enzyme. The K , Bpp values for the immobilized enzyme were found to be 0.25M in the presence of 0.01M Mg2+ and 0.19M with O.OO5M Mg2+, while those for the soluble enzyme were 0.11 and 0.17M, respectively. Under conditions of continuous isomerization of D-glucose, a decrease of activity with time was observed, but this decrease was less at a low Mg2+ concentration and was affected by column geometry. There were no appreciable diffusional limitation effects in packed-bed columns.