A new immobilization of microbial cells

Summary A new immobilization of microbial cells based on the growth of cells in gel is presented. The cells grew very well in carrageenan gel when fed nutrients required for growth. The growing cells immobilized in gel formed a dense layer of cells near the gel surface. Because the cells were near the gel surface, they efficiently catalyzed single enzyme reactions. In addition, the immobilized growing cell system was applied to the complicated multienzyme reactions since large numbers of cells in the gel could constantly be maintained for long periods.     

Automated rapid method for microbioassay of amino acids

An automated rapid method for microbioassay of amino acids was investigated by taking advantages of the rapid manual method. The Pye Unicam automatic analytical apparatus was adopted for the automation of assay culture in the rapid microbioassay. The advantages of the present method are that amino acids can be automatically determined on 3.5-hr assay culture, and that an aseptic technique can be omitted. These advantages were confirmed in several amino acid assays. The assay values were the same as those obtained by the conventional method. Application of the automated rapid method to the serine assay showed a linear standard curve without a lag section, leading to more expanded assay range and smaller drift in values.     

Metabolism of Pyrimidine Nucleotides in a Microorganism: III. Enzymatic Production of Ribose-5-Phosphate from Uridine-5′-Monophosphate by Pseudomonas oleovorans

A study was made to develop a new method for the production of ribose-5-phosphate (R-5-P) from uridine-5'-monophosphate (UMP) by the action of nucleotide-N-ribosidase of Pseudomonas oleovorans, and a suitable medium for the formation of nucleotide-N-ribosidase was established. For the enzymatic conversion of UMP to R-5-P, a cell suspension was employed as the enzyme source. Although degradation of R-5-P, the desired product, occurred during the course of the enzyme reaction, it was prevented by the addition of an appropriate amount of zinc ion and resulted in a stoichiometric conversion of UMP to R-5-P and uracil. Accumulated R-5-P was readily isolated by ion-exchange chromatography of the bacteria-free reaction mixture. Yield of isolated R-5-P was about 60% of the theoretical recovery.     

Stimulation of L-asparate beta-decarboxylase formation by L-glutamate in Pseudomonas dacunhae and Improved production of L-alanine

The formation of L-asparate beta-decarboxylase by Pseudomonas dacunhae was compared on media containing a variety of organic acids and amino acids as a carbon source. Although the enzyme was formed constitutively when the organism was grown on basal medium or on that containing tricarboxylic acid cycle intermediates, it was induced twofold by L-glutamate and repressed one-tenth by L-serine. L-Glutamine, L-proline, L-leucine, glycine, and L-threonine also showed induction effects lower than that of L-glutamate. L-Glutamate derepressed the serine effect. This glutamate effect was observed effect was observed with other microoganisms, e.g., Achromobacter pestifer and Achromobacter liquidum. Since the intermediates from L-glutamate metabolism had no effect, this induction effect was specific to L-glutamate. The formation of some glutamate-related enzymes was measured and is discussed in relation to the formation of L-asparate beta-decarboxylase. L-Asparate beta-decarboxylase was purified to an electrophoretically homogenous state from L-glutamate-grown cells of P. dacunhae, and some properties were compared with those of the enzyme from fumarate-grown cells. The two enzymes were identical in disc electrophoresis, molecular weight, and some enzymatic properties. The industrial production of L-alanine from L-aspartic acid acid was improved by using the culture broth with highly induced L-asparate beta-decarboxylase (9.4 U/ml of broth).     

Continuous production of L-arginine using immobilized growing Serratia marcescens cells: Effectiveness of supply of oxygen gas

Summary The immobilized growing cell system using Serratia marcescens was applied to continuous L-arginine production. From the determination of oxygen uptake rate, it was shown that the cells entrapped in carrageenan gel were in an oxygen-limited state due to the diffusion barrier to oxygen transport created by the gel layer. This limited state in gel was relieved by supply of oxygen-enriched gas instead of air into the medium. The maximum population of immobilized cells increased to five times that of free cells with the supply of pure oxygen gas. The L-arginine-producing activity of the immobilized growing cells was proportional to the concentration of oxygen gas supplied and was 6 mg/h per millilitre in gel supplied with pure oxyges gas. The continuous L-arginine containing production was constantly maintained by controlling the medium penicillin G at pH 6.5 and more than 10 mg/ml of L-arginine were obtained at 10h of residence time for at least 12 days.     

Studies on immobilized enzymes. IX. Preparation and properties of aminoacylase covalently attached to halogenoacetylcelluloses

Immobilization of mold aminoacylase (N-acylamino acid amidohydrolase, EC 3.5.1.14) was investigated by covalently binding the enzyme to halogenoacetylcelluloses. As a result, the iodoacetylcellulose was found to be the best carrier among the halogenoacetylcelluloses. The yield of activity of the insoluble aminoacylase relative to that of the native aminoacylase used was 40–50%, and the specific activities of both enzyme preparations were the same within the limits of error of the estimation.