Mitsuo Okazaki

Model system of bulking and flocculation in mixed culture of Sphaerotilus sp. and Pseudomonas sp. for dissolved oxygen deficiency and high loading

Abstract A mixed continuous culture system was made up as a model for bulking and flocculation phenomena of the activated sludge to study the effect of dissolved oxygen (DO) deficiency and the effect of high organic loading. The system consisted of a floc forming bacterium and a filamentous bacterium which were isolated from the activated sludge and were identified as Pseudomonas sp. and Sphaerotilus sp., respectively. Sphaerotilus sp. had potential to cause a filamentous bulking phenomenon on the activated sludge. It was observed that the filamentous microorganism showed three kinds of growth form, filamentous form, pellet form and dispersed form, and that the floc former showed two kinds of growth form, good floc form and dispersed form. In the model system, these changes of growth form of two microorganisms, which could be thought as the cause of settling characteristics changes, depended on the DO level and the dilution rate (as a substitution for organic loading). The DO level also influence the aggregative ability of each microorganism and the maximum oxygen uptake rate, QO2max, of filamentous microorganism. The proportions of both microorganisms in model system were inverted reversibly by the DO level or the dilution rate changes.

HORMONAL REGULATION OF SCOPOLETIN AND SCOPOLIN PRODUCTIONS IN TOBACCO TISSUE CULTURE

ABSTRACT The additions of L-phenylalanine and kinetin increased the productions of scopoletin and scopolin in tobacco tissue culture. The effect of kinetin was attributable to the increase of the metabolism of phenylalanine to scopoletin and scopolin. Furthermore, kinetin stimulated the activity of L-phenylalanine ammonia-lyase (PAL). These results suggested that the increase of the metabolism of phenylalanine to scopoletin and scopolin was caused by the increment of PAL activity. On the other hand, 2,4-dichlorophenoxyacetic acid (2,4-D) increased the content of scopolin, which was mono-glucoside of scopoletin. The effect of 2,4-D was caused by the increment of the activity of UDP-glucose:scopoletin glucosyltransferase (SGTase), which catalized the conversion of scopoletin to scopolin. The increment of PAL activity was inhibited by actinomycin-D or cycloheximide, but the increment of SGTase activity was observed even if RNA and protein syntheses were inhibited by them. These results suggested that the increment of PAL activity occurred as a result of the de novo synthesis of the enzyme, while that of SGTase activity occurred as a result of the activation of the already present enzyme.

Detoxification of ammonia by immobilized urea cycle enzymes.

Detoxication of ammonia was performed by dialysis of ammonia through a hollow fiber unit and by conversion to urea in a column reactor packed with immobilized urea cycle enzymes. Enzymes in the urea cycle could be immobilized by covalently binding on CNBr-activated Sepharose 4B. Ammonia was sequentially converted to urea by immobilized urea cycle enzymes with an ATP-regenerating system. Optimum conditions for the cyclic reaction were obtained theoretically and experimentally for performing continuous urea synthesis in a packed column reactor. Detoxication of ammonia of similar concentration to that in the blood in hepatic insufficiency was analyzed and performed experimentally in an extracorporeal model.

Activity of Enzyme Immobilized by Microencapsulation

It is well known that the immobilization may alter both the chemical and physical properties of an’enzyme, such as its pH-activity behavior, apparent saturation constant, Km, substrate specificity and stability toward conformational inactivation, in addition to simply restricting its gross physical movement. The enzyme activity is generally decreased through immobilization. It is necessary for obtaining an immobilized enzyme preparation of high activity to discuss the processes of enzyme immobilization and investigated the factors affecting the activity and yield of immobilized enzyme. In the present work, we discussed the processes of enzyme immobilization by microencapsulation and clarified the factors affecting the activity and yield of enzyme immobilized.