The yield of fibrinolytic and other proteolytic enzymes by Ca-alginate immobilized cells of Penicillium chrysogenum H9 was compared to that of free cells. The gel matrix protected the immobilized cells from lysis providing higher stability to the biocatalyst. The highest fibrinolytic activity/caseinase activity ratio was obtained in immobilized cell cultures. The composition of culture medium influenced enzyme production, showing different patterns in free and immobilized cultures. An alginate concentration of 3% and 10 ml alginate beads/50 ml medium were optimum for fibrinolytic enzyme biosynthesis. Semicontinuous production of the enzyme indicated the superiority of immobilized cells. The beads were affected by repeated exposure to phosphate ions after 12 cycles.

The production of an antibiotic by free and immobilized cells of Streptomyces violatus through entrapment or adsorption on different materials was investigated. S. violatus entrapped in Ca-alginate beads gave low antibiotic activity compared to the free cell or adsorbed cell, while the adsorption of S. violatus on sponge cubes yielded the highest antibiotic concentration after 4 days of incubation in static cultures. A starch concentration of 10 g/L was optimum for the production of the antibiotic by adsorbed cells. The weight and size of the sponge cubes used for immobilization influenced production of the antibiotic and the optimum weight and size of the sponge were 0.8 g and 1.0 cm(3), respectively, yielding a maximum antibiotic production of 280 mg/ml. Maximum antibiotic production was obtained at an initial pH value of 7.5 and in an inoculum size of 3 ml (spore suspension) per 50 ml. The production of the antibiotic in a fixed-bed bioreactor reached a maximum value after 2 days of incubation at a circulation rate of 30 ml/h. The immobilized cells in the bioreactor were reused seven successive times over a period of 14 days.

Acetone fractionation o f Bacillus lentus culture filtrate yielded the highest a-amylase activity and the 66.6% fraction reached 13-fold that o f the crude enzyme preparation. Gel filtration and ion exchange chrom a t o g r a p h y afforded a pure a-amylase (relative molecular mass, 42000). The pure enzyme was highly active on starch and dextrin~ It produced a mixture o f oligosaccharides as major products o f starch hydrolysis. Maximal activity was reached at 70°C and p H 6.1. Ca 2÷, N a +, K + and Sr 2+ ions stabilized or slightly stimulated the enzyme whereas A g +, Co 2+, H g z+, Zn 2+, Cd z+ and Fe 3÷ ions strongly inhibited the activity. The enzyme contained 16 amino acids, o f which aspartic and glutamic acids were present in the highest proportions.

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Reichstein's compound S was transformed into prednisolone in a single‐step fermentation using immobilized mixed cultures, entrapped in different gels or adsorbed on clay particles. Calcium alginate at a gel concentration of 2% gave the highest transformation activities and prednisolone yields. The entrapped mixed cultures could be repeatedly used in batch‐wise transformation for at least six times when suspended in diluted nutrient medium and for three times when suspended in distilled water; in the latter case the entrapped cultures required to be reactivated in nutrient medium for further reuse. Mixed cultures adsorbed on clay particles were successfully reused 18 times, with reactivation after the 9th and 15th uses. Continuous transformation of substance S into prednisolone by mixed cultures adsorbed on clay particles was more efficient than batch‐wise reused adsorbed cultures and was dependent on the daily working medium volume.

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