Performance of a perforated plate column as a multistage continuous fermentor

Microorganisms were continuously cultivated in multistage column consisting of ten perforated plate sections to which medium and air were supplied concurrently from the bottom. At steady state the cell concentration in the various stages was gradationally differentiated from the bottom to the top in the direction of medium flow. RNA content per unit cell concentration at each sage was determined. The cells in the lower stages were higher in RNA content than those from the upper stages. Wash out was observed to occur in the column at dilution rates which do not result in wash out in a single stage chemostat system. A study of the flow characteristics revealed that the overall performance of the plate column was equivalent to that of a multistage system, when hole diameter and hole area to column cross sectional area ratio were properly selected. This was true even in highly aerated conditions. These results indicated that the perforated plates in the column hindred intermixing through the plates, and that each stage functioned as an independent stirred vessel. Industrial and research application of this type fermentor was discussed.     

Solution properties of synthetic polypeptides. V. Helix–coil transition in poly(β-benzyl L-aspartate)

Simple approximate expressions have been derived from the theory of Zimm and Bragg for use in the analysis of experimental data on the helix-coil transition in polypeptide. On the basis of the resulting expressions practical procedures are proposed to determine two basic parameters characterizing a thermally induced transition, i.e., helix initiation parameter σ and enthalpy change for helix formation, ΔH. They have been applied to the data for poly(β-benzyl L -aspartate) (PBLA) with the result: σ = 1.6 × 10^?4 and ΔH = ?450 cal/mole for PBLA in m-cresol; σ = 0.6 × 10^?4 and ΔH = 260 cal/mole for PBLA in chloroform containing 5.7 vol-% of dichloroacetic acid. This result gives evidence that σ may change not only from one polypeptide to another but also for a given polypeptide in different solvents. The change in limiting viscosity number [η] accompanying the transition was measured in the same solvents. The curve of [η] versus helical content had a relatively monotonic shape for the chloroformdichloroacetic acid solutions as compared with that for the m-cresol solutions, indicating that [η] depended largely on σ. Provided that [η] is a direct measure of the mean-square radius of gyration, 〈S²〉, the results are consistent with the theoretical predictions of Nagai and of Miller and Flory for 〈S²〉.     

Use of the Stereoisomers of Isoleucine by Lactobacillus fermenti

The use of four stereoisomers of isoleucine by Lactobacillus fermenti strain 36 was studied in detail. All four isoleucine isomers were used for growth in the presence of vitamin B(6) compounds, but only l-isoleucine was active in the absence of these vitamins. Of the vitamin B(6) compounds, pyridoxal and pyridoxamine were equally more effective than pyridoxine for the utilization of these isomers. Lowering the initial pH, decreasing the amounts of leucine and valine, and adapting the organism to d-alloisoleucine medium accelerated the use of isoleucine isomers. Thus, the conditions were established under which respective isomers gave the same growth response, and these findings were applied to the separate microbiological assay of l-isoleucine and total isoleucine isomers.     

Fermentation Studies with Streptomyces griseus: II. Synthetic Media for the Production of Streptomycin

Synthetic media for streptomycin fermentation were studied to determine which media gave highest yields of streptomycin. The effect of salts on streptomycin production by Streptomyces griseus was examined, and a suitable combination of salts was established in a glucose-casein medium. This medium yielded 3,000 μg/ml of the antibiotic with an inoculum of 1.6%. Substitution of amino acids for casein was examined. Of 17 amino acids tested, best results were obtaind with sodium aspartate. Substitution of ammonium salts was tried, and an excellent streptomycin yield was obtained with a medium containing ammonium citrate.     

Effects of serine protease inhibitors on oxyradical burst from phagocytizing neutrophils—analysis by chemiluminescence counting and its microscopic imaging

Reaction difference of oxyradical generation and luminol-dependent photoemission of zymosan- and phorbol ester-treated neutrophils were investigated using a conventional photomultiplier and ultrasensitive photonic imaging technique. Zymosan-treated cells released a concentrated photonic burst corresponding to the cellular distribution. In contrast, phorbol ester-treated cells produced a negligible level of photoemission, and the additional application of Ca²⁺ ionophore enhanced the photonic burst, which was gradually spread out into extracellular space. Serine protease inhibitors did not attenuate PMA-induced chemiluminescence but did attenuate zymosan-induced chemiluminescence. This suggests the involvement of serine protease in the respiratory burst of phagocytizing neutrophils.     

Spectral studies of the Ca2+-dependent interaction of trifluoperazine with S100b

S100b is a calcium-binding protein that will bind to many calmodulin target molecules in a Ca²⁺-dependent manner. In order to study the Ca²⁺-dependent binding properties of S100b, its interaction with a calmodulin antagonist, trifluoperazine (TFP), was investigated using [¹⁹F]- and [¹H]-NMR and UV-difference spectroscopy. It was estimated from [¹⁹F]-NMR that in the absence of Ca²⁺, thek _1/2 value of TFP was 130 µM, while itsk _1/2 value decreased to 28 µM in the presence of Ca²⁺. The addition of KCl was not antagonistic to the Ca²⁺-dependent interaction of TFP to S100b. The chemical exchange rate of TFP with Ca²⁺-bound S100b was estimated to be 9×10² sec^?1. By comparison with TFP-calmodulin exchange rates, it is suggested that the TFP-binding site on S100b is structurally different from its binding sites on calmodulin. Proton NMR resonance broadening in the range 6.8–7.2 ppm, corresponding to phenylalanine nuclei of S100b, indicates that these residues may be involved in TFP binding. Addition of Ca²⁺ to a 1:1 mixture of S100b and TFP resulted in a red-shifted UV-difference spectrum, while no significant difference spectrum was detected when Mg²⁺ was added to a S100b-TFP solution. Thus, we suggest that Ca²⁺ induces the exposure of a hydrophobic domain on S100b containing one or more phenylalanine residues that will bind TFP but that this domain is different from the hydrophobic domain on calmodulin.