The shift of a synchronous culture of the fission yeast, Schizosaccharomycespombe, from a poor to a rich medium resulted in division delay. The mean time period from the shift till division was nearly constant, regardless of the time of shift in the cell cycle. The time period from the shift till division of the individual cells was negatively proportional to cell size at the shift. The division size of the shifted cells was larger than that of exponentially proliferating cells. From these results, the dependence of the timing of division on cell size at the shift, not at division, is discussed.
Using a rapid continuous flow system (D=1), growth rates and molar growth yields of free and adsorbed cells of Escherichia coli were determined with glucose as a limiting substrate. In this system, free cells were continuously removed and a steady state in cell or substrate concentration in the liquid phase of culture was realized by the growth of adsorbed cells. Growth constants of free cells, μ and Y, were obtained from a washout curve of free cells and a corresponding curve of increase of a substrate. Growth constants of adsorbed cells, μa and Ya, were obtained from steady state concentrations of cell and substrate in the liquid phase of culture during cultivation of adsorbed cells. The growth rate of adsorbed cells depended both on substrate concentration and the amount of adsorbed cells. Saturation constants for growth, KS, with glucose as a substrate were extremely high and they also depended on the amount of adsorbed cells. The maximal growth rate and the molar growth yield of adsorbed cells were much higher than those of free cells.
Treatment of Bacillus natto (Asahikawa) with acridine orange resulted in the conversion of approximately 64.2% of the population to stringiness negative, which is indicative of the involvement of plasmid deoxyribonucleic acid (DNA). Cleared lysate materials were subjected to agarose gel electrophoresis to determine the plasmid composition of each strain. B. natto (Asahikawa) was found to possess a plasmid of approximately 4.2 megadaltons (Mdal). A 4.2 Mdal plasmid has been found to be missing in the stringiness-negative mutants cured by acridine orange. Gamma-GTP activity was also deficient in the stg- mutants which were missing the 4.2 Mdal plasmid.
The L-α-aminoamidase of Brevibacterium A4 is a particle enzyme with a molecular weight of 135, 000; its optimum pH is 9.5 and its optimum temperature 60°. It is probably a metallo-enzyme with an SH group in the active site, and requiring the presence of Mg2+ or Mn2+. The purification tests showed that it hydrolyses a large number of α-aminoamides. The Michaelis constant Km varies little for the different substrates. On the other hand the Vm varies greatly, in particular according to the hydrocarbon chain length. The use of the α-amidoamidasic activity for the preparation of optically active, natural or non-natural α-aminoacids has been considered.
NADH dehydrogenase (EC 184.108.40.206), which catalyzes the first reaction of the NADH oxidase system known to operate actively at low temperature in Vibrio sp. strain ABE-1, was examined in respect of intracellular distribution, temperature- and salts-dependencies, and so on. Almost the same amount of the enzyme was distributed in the cytoplasmic and membrane fractions, and the enzymes in the two fractions were presumed to be different ones by virtue of their properties such as optimum pH, salts- and temperature-dependencies. Both enzymes were unique in that they were able to function at a remarkably high rate under lower temperatures: the activities at 5° were about 70% of the respective maximum activities.
Invertase is immobilized using an inorganic solid support, Molecular sieve 4A, via the metal link method. Bound enzyme showed maximum activity at pH 4.8 which was similar to that of soluble enzyme. Protein to solid support ratio was very critical for the retention of active invertase as loading beyond 18-20mg protein/g MS significantly decreased bound invertase activity. Km for the soluble and immobilized enzyme were found to be 20mM and 50mM respectively. Bound enzyme retained 90% original activity after 45 days at room temperature. Half-life for the continuous conversion of sucrose using MS-bound invertase was calculated to be 26 days. Used MS could be regenerated using perchloric acid. Regenerated MS did not require titanium activation and could retain 90% of the enzyme activity as compared to the control. Ammonium sulphate treatment was not effective in the regeneration of MS, indicating the enzyme is bound to MS by covalent linkage.