bluuebunny/crossref_metadata_2025 huggingface dataset:
Model connective tissue system: The effect of proteoglycans on the distribution of small non‐electrolytes and micro‐ions
Authors: Preston B. N. , McK. Snowden J. , Houghton K. T.
Published: December 2004

Donnan equilibria between solutions of various carbohydrates polyins and Na⊕ have been measured by equilibrium dialysis. From the results, estimates have been made of the degree of Na⊕ fixation by the polyions. Comparison is made between the behavior of the complex proteoglycan macromolecules and their constituent glycosaminoglycans. Attempts to interpret these results and the Na⊕ activity in saltfree solutions on the parameter of the intercharge distance has been made. By use of studies on carboxymethylcellulose, the relative importance of the carboxyl and of the sulphate ester groups in the Na⊕ fixation is assessed. The relevance of the measurements to the previously described diffusional effects found in real and model connective tissues is discussed.
The kinetics of the renaturation of deoxyribonucleic acid denatured in the presence of copper (II) ions
Authors: Holman Lynette R. , Jordan D. O.
Published: December 2004

DNA which has been heat denatured in the presence of Cu++ ions can be completely and rapidly renatured by increasing the ionic strength of the solution above a critical value. A kinetic study of this renaturation recation was carried out by following the associated UV absorbance change and also by following the change in free Cu++ ion concentration by means of a specific Cu++ ion activity electrode. The data obtained could be fitted to first‐order kinetics for a considerable extent of the reaction and the rate constant was found to increase with temperature and ionic strength, but to decrease markedly as the bulk viscosity of the solution was increased. At temperatures greater than 5°C the reaction rate depended on the time elapsing between denaturation and the commencement of the renaturation reaction. As there was good agreement between the rate constants obtained by following the decrease in hyperchromism and by following the increase in free Cu++ ion concentration, it is concluded that under the conditions employed, the rate of renaturation is determined by the rate of release of Cu++ ions from the denatured DNA‐Cu++ complex.
The conformation of histone f2a1 (histone IV) in solution at low inoic strength
Authors: Ziccardi Robert , Schumaker Verne
Published: December 2004

Hydrodynamic studies of histone f2a1 are performed in dilute salt solution. Protein sedimentation is shown to be dependent upon the partial specific volume and molarity of the supporting electrolyte. To compensate for the secondary chage effect, a solvent of dilute tetramethylammonium chloride, for which (1 − V̄saltρ) ≅ 0, is used. To correct for the primary charge effect in sedimentation, a special linear extrapolation to infinte dilution of the protein is employed. Measurements of intrinsic viscosity are interpreted in terms of an increase in molecular dimension with a decrease in ionic strength. The conformation of histone f2a1 in dilute salt solution is interpreted from sedimentation and viscosity data to be that of a highly charged random coil possessing 20–30% of nuclear globular structure.
Normal vibrations of polyglycine II
Authors: Abe Yasuaki , Krimm S.
Published: December 2004

A valence force field has been refined for single‐chain polyglycine II using the known structure and four isotopic derivatives. The calculated frequencies are in good agreement with the observed. The force field is compared with that derived from polyglycine I and for the nylons.
Raman studies of the helix‐to‐coil transition in poly‐L‐glutamic acid and poly‐L‐ornithine
Authors: Koenig J. L. , Frushour Bruce
Published: December 2004

The conformational transitions in water and in the solid state of poly‐L‐glutamic acid (PGA) and poly‐L‐ornithine (PO) have been studied by Raman spectroscopy. The Raman spectra of PGA, PO, and the monomer, dimer, and trimer of PGA in aqueous solutions and solid state are presented. The Raman spectral changes of PGA and PO were followed through the helix‐to‐coil transition induced by pH, temperature, and solvent composition. A hyperchromic shift in the intensity of the amide III line accompanying the helix‐to‐coil transition was observed. This hyperchromic intensity shift occurs abruptly as a function of pH but more slowly with heat denaturation of the alpha helix indicating that the Raman spectrum is sensitive to the transition mechanism. The high‐temperature coil and the charged coil may have different conformations as evidenced by different amide III frequencies but similar intensities in these two conformations.
Sedimentation equilibrium of DNA samples heterogeneous in density
Authors: Schmid Carl W. , Hearst John E.
Published: December 2004

The problem of determining the molecular weight of DNA samples by sedimentation equilibrium in a buoyant‐density gradient is considered for the case of DNA samples with density heterogeneity. By determining apparent molecular weights in two or more buoyant mediums, quantitative measure of the amount of density heterogeneity can be determined. This method may be employed to determine both the true molecular weight and the extent of base composition heterogeneity.
The linear dichroism of oriented helical and superhelical polymers
Authors: Rill Randolph L.
Published: December 2004

Expressions are derived to relate the linear dichroism of oriented helical and super‐helical polymers to the vector equation describing a transition moment in a reference frame based on the position of a single monomer unit in a simple helix and the super‐helix tilt angle β. The reduced dichroism of a perfectly oriented superhelical polymer, (Δε/ε)0, is related to the reduced dichroism of a perfectly oriented helical polymer, (Δε/ε)1, by the expression (Δε/ε)0 = ½ (Δε/ε)1(3 cos2 β − 1). Hence the linear dichroism of a helical polymer can be significantly altered by supercoiling. The application of the general expressions is illustrated by the derivation of specific equations which relate the dichroism of helical and superhelical DNA to the tilt and twist of the DNA bases, the directions of the transition moments within the base planes, and the superhelix tilt angle. Calculations of the reduced dichroism of perfectly oriented, non‐super‐helical DNA in the A and B configurations suggest that it will be difficult to distinguish between these two forms on the basis of dichroism measurements.
Poly(L‐alanine): Investigation of alpha‐helix and betal‐sheet forms by low‐temperature specific heat measurements (1.5–20°K)
Authors: Finegold Leonard , Cude Jesse L.
Published: December 2004

For an ideal one‐dimensional solid, the low‐temperature specific heat, C, is proportional to temperature T1, for an ideal two‐dimensional solid C is proportional to T2. We have observed such one‐ and two‐dimensional behavior in alpha‐ and beta‐poly(L‐alanine) in the temperature range 1.5–20°K (also intermixed with a three‐dimensional behavior). A specific heat anomaly has also been observed. These measurements are important in evaluating the effective elastic constants, including hydrogen bonding, of the biopolymers. They also provide essential information for vibrational theories of poly(L‐alanine), which up until now have been based on high‐energy data.
On the application of polyelectrolyte limiting laws to the helix–coil transition of DNA. V. Ionic effects on renaturation kinetics
Authors: Manning Gerald S.
Published: December 2004

The bimolecular rate constant k2 for the association of complementary polynucleotide strands has been observed to increase strongly with increasing ionic strength—in fact, proportional to its third or fourth power. This effect is here interpreted quantitatively by means of polyelectrolyte theory starting with the Wetmur–Davidson postulate of a pre‐equilibrium between separated strands and aligned segments close to one another but unbonded. The correct form, a power dependence of k2 on ionic strength, is predicted. Comparison of the theoretical exponent with data allows the conclusion that each of the two single‐stranded segments in the aligned but unbonded configuration consists of about 13–16 nucletides (not to be confused with the much smaller number of bonded base pairs in the nucleus), and that this number, denoted by Q, is possibly correlated either with a minimum length for duplex stability or with the persistence length of a single polynucleotide strand. It is suggested that experimental determination of the dependence of Q on (G+C)‐content may distinguish between these possibilities. It is also suggested that addition of sufficient amounts of divalent metal ions such as Mg2+, Ca2+, or Co2+ may reverse the dependence of k2 on ionic strength; under these conditions, k2 is predicted to decrease with about the first power of ionic strength. At fixed ionic strength, k2 should increase with increasing concentration of divalent metal ion, and, in fact, the published observation that the formation of poly(A)·2 poly(U) from poly(A)·poly(U) and poly(U) is second order in Mg2+ concentration is here correctly predicted from a priori molecular considerations. Finally, published association rate data for oligonucleotides are discussed in the present theoretical context.
Interaction of aminoacridines with deoxyribonucleic acid: Effects of ionic strength, denaturation, and structure
Authors: Drummond D. S. , Simpson‐Gildemeister V. F. W. , Peacocke A. R.
Published: December 2004

The binding curves of various aminoacridines on calf thymus DNA have been determined by a spectrophotometric method. The dominant role of electrostatic forces in the interaction has been confirmed by the effect of ionic strength. Side chain and ring substituents in the aminoacridines do not inhibit binding, since this decreases in the order: acranil > neomonacrin > atebrin > 9‐aminoacridine ∼ proflavine > 9‐amino‐1,2,3,4‐tetrahydroacridine (THA). The last named shows the effect of diminishing the flat area of the rings in the aminoacridines. The shape of the binding curves of proflavine, 9‐aminoacridine, and THA on thermally denatured DNA show that about 30–50% more binding sites are available to these cations on denatured DNA than on native DNA, but that the binding constants are the same. These observations are discussed in relation to the intercalation and other models for the interaction. It is concluded that exact and complete intercalation is not a necessary condition of strong binding and that other, less regular, models, in which the positive ring nitrogens of the acridines are close to the DNA phosphates and the acridine rings partially interact with the DNA base rings, are probably more consistent with the effect of denaturation of DNA on the binding curves which are characteristic of the interaction in solution.
Statistical mechanics of noncovalent bonds in polyamino acids. I. Hydrogen bonding of solutes in water, and the binding of water to polypeptides
Authors: Poland Douglas C. , Scheraga Harold A.
Published: December 2004

By using the Nemethy‐Scheraga theory of water structure, a calculation was made of the energy changes for the rupture of a DH…︁A solute–solute hydrogen bond in water. A partition function was also obtained for the binding of water and other solutes to the DH and A groups in the special case where these are the NH and CO groups of a random coil polypeptide chain. In subsequent papers of this series, these calculated quantities will be used in a statistical mechanical treatment of the helix–coil transition for polypeptides in water.
Statistical mechanics of noncovalent bonds in polyamino acids. V. Treatment of long chains by the method of sequence‐generating functions: Hydrophobic bonding in random coil, and interactions between helical segments
Authors: Poland Douglas C. , Scheraga Harold A.
Published: December 2004

The method of sequence‐generating functions is applied to long polypeptide chains to describe various types of hydrophobic bonding in the random coil. These results are then combined with a similar treatment of the α‐helix in order to discuss the helix–coil transition in single helices and in molecules whose helical segments interact by side‐chain hydrophobic bonding. Numerical calculations, based on the equations derived in this and preceding papers, are presented to show the relative probabilities of occurrence in the random coil of neighbor–neighbor hydrophobic bonds and pockets of hydrophobic bonding, and the relative probabilities of occurrence of the various states in a system of interacting helices. A discussion is also presented of the dependence of the helix–coil nucleation and growth parameters on solvent and side chain.
NMR study of the secondary structure of s‐RNA
Authors: McDonald C. C. , Phillips W. D. , Penswick John
Published: December 2004

The melting characteristics of unfractionated yeast s‐RNA in neutral aqueous solution have been examined by high‐resolution proton magnetic resonance spectroscopy. These studies indicate that the bases of s‐RNA become rotationally activated at lower temperatures than their associated ribose units. These observations, as well as the recently determined base sequence of an alanine‐specific s‐RNA, suggest that base complementarity may not be the primary determinant in the stabilization of the secondary structure of s‐RNA. In addition, evidence for exchange of C8‐protons of purine bases of s‐RNA with D2O was obtained at temperatures above 70°C.
Precision space‐filling atomic models
Authors: Koltun Walter L.
Published: December 2004

Shortly, lightweight, inexpensive, precision, space‐filling atomic models particularly suitable for constructing macromolecules of biological interest will reach the scientific community. The availability of the models, the Corey‐Pauling‐Koltun, or C‐P‐K Models, will conclude a five‐year program which has involved the cooperative efforts of Federal agencies, scientific societies, and selected scientists. This paper describes the development of the program, details the contributions of the various groups and persons who have been involved, and discusses the technical characteristics of the models.
Impact of external calcium and calcium sensors on ginsenoside Rb1 biosynthesis by Panax notoginseng cells
Authors: Yue Cai‐Jun , Zhong Jian‐Jiang
Published: December 2004

The effects of external calcium concentrations on biosynthesis of ginsenoside Rb1 and several calcium signal sensors were quantitatively investigated in suspension cultures of Panax notoginseng cells. It was observed that the synthesis of intracellular ginsenoside Rb1 in 3‐day incubation was dependent on the medium Ca2+ concentration (0–13 mM). At an optimal Ca2+ concentration of 8 mM, a maximal ginsenoside Rb1 content of 1.88 ± 0.03 mg g−1 dry weight was reached, which was about 60% and 25% higher than that at Ca2+ concentrations of 0 and 3 mM, respectively. Ca2+ feeding experiments confirmed the Ca2+ concentration‐dependent Rb1 biosynthesis. In order to understand the mechanism of the signal transduction from external Ca2+ to ginsenoside biosynthesis, the intracellular content of calcium and calmodulin (CaM), activities of calcium/calmodulin‐dependent NAD kinase (CCDNK) and calcium‐dependent protein kinase (CDPK), and activity of a new biosynthetic enzyme of ginsenoside Rb1, i.e., UDPG:ginsenoside Rd glucosyltransferase (UGRdGT), in the cultured cells were all analyzed. The intracellular calcium content and CCDNK activity were increased with an increase of external Ca2+ concentration within 0–13 mM. In contrast, the CaM content and activities of CDPK and UGRdGT reached their highest levels at 8 mM of initial Ca2+ concentration, which was also optimal to the ginsenoside Rb1 synthesis. A similar Ca2+ concentration‐dependency of the intracellular contents of calcium and CaM and activities of CCDNK, CDPK, and UGRdGT was confirmed in Ca2+ feeding experiments. Finally, a possible model on the effect of external calcium on ginsenoside Rb1 biosynthesis via the signal transduction pathway of CaM, CDPK, and UGRdGT is proposed. Regulation of external Ca2+ concentration is considered a useful strategy for manipulating ginsenoside Rb1 biosynthesis by P. notoginseng cells. © 2004 Wiley Periodicals, Inc.
Fermentation mixing scale‐up techniques
Authors: Oldshue J. Y.
Published: December 2004

Scale‐up of a mixing process in fermentation involves breaking the process down into individual but interrelated steps. The effect of mixing on gas‐liquid absorption, fluid shear rates, blending, and heat transfer allows each to be considered separately. A method of estimating the mixer size required in a full‐scale system from pilot studies illustrates the application of a particular technique.
Kinetics of polysaccharide B‐1459 fermentation
Authors: Moraine R. A. , Rogovin P.
Published: December 2004

Polysaccharide gum was made by fermentation with Xanthomonas campestris NRRL B‐1459 in a medium of glucose, minerals, and distillers' solubles. The effect of distillers' solubles on growth rate can be described by the familiar saturation equation. Although a quasistoichiometric relationship was observed between nitrogen utilization and growth, total nitrogen supply was not growth limiting, nor was polymer formation growth associated. Cell growth primarily took place in the early part of the fermentation; polysaccharide biosynthesis occurred throughout the fermentation. Glucose was converted to polysaccharide at a fairly constant yield, which was 70–80% of glucose consumed, under optimum conditions. The kinetic patterns observed indicate that multistage continuous fermentation will be suitable for polysaccharide production.
Utilization of gas oil by a yeast culture
Authors: Miller Thomas L. , Johnson Marvin J.
Published: December 2004

A mixed yeast culture (Culture 4) was grown on representative gas oil samples as well as paraffin wax. Culture 4 was found to utilize n‐paraffinic hydrocarbons almost quantitatively from most gas oil fractions; significant alteration of other hydrocarbon components was not detected. Generation times of 4.0–9.0hr. were typical during the exponential growth phase in fermentations with various gas oil fractions. Cell yields were 70–90% based on n‐paraffin utilization. The culture appeared to exhibit maximum efficiency of n‐alkane removal in the C19 to C24 range. The cells recovered from the fermentations contained 8.8–9.3% nitrogen. Paraffin wax also served as a suitable carbon source when dissolved in 2,6,10,14‐tertramethylpentadecane (pristane). However, substrate utilization appeared to be incomplete.
Utilization of mixed sugars in continuous fermentation. II.
Authors: Harte M. J. , Webb F. C.
Published: December 2004

Batch growth characteristics of various organisms were determined on a number of pairs of sugars to find a stable system showing clear‐cut classical diauxie. The system selected for further study was a strain of Klebsiella (Acrobacter) aerogenes, NCIB 8021 growing on a mixture of glucose and maltose in minimal salts medium at 30°C. This showed a specific growth rate (μ) of 1.19 ± 0.03 hr.−1 on 0.01% (w/v) glucose, followed by a diauxie lag of 0.73 ± 0.04 hr and then further growth on 0.01% (w/v) maltose at μ = 0.60 ± 0.03 hr−1. This system was applied to a two‐stage continuous, stirred, aerated fermentor system, with working volumes of 1.85 and 2.77 liters, respectively, and growth was followed (mainly by optical density, referred to dry weights and viable counts) and also the concentrations of the sugars were measured. Except at the very highest flow rates, glucose was immediately and virtually completely consumed, but the utilization of maltose showed interesting variations: (a) At low feed rates between 0.09 and 0.4 vol./hr. exactly the same response was found with mixed sugars as with double concentration glucose, showing that the organism was able to metabolize maltose as well and as quickly as glucose. (b) At medium feed rates of 0.46 to 1.03 vol./hr. two deviations were observed, both of which increased as the dilution rate increased: the system showed a time lag on maltose before the cell population began to rise and the volume of medium used before the steady state was established was greater than predicted, (c) At fast feed rates, approaching “washout” condition of 1.055 to 1.135 vol./hr. the first culture vessel showed no reaction to a step change which included maltose, although, of course, with doubled glucose it responded immediately. The second vessel, however, quickly metabolized the overflow maltose, and showed a steady increase of cell population to the theoretical steady state. These results may have significance for industrial systems using complex commercial substrates.
Geosmin, an earthy‐smelling substance isolated from actinomycetes
Authors: Gerber Nancy N.
Published: December 2004

Geosmin, an earthy smelling substance, has been obtained from several actinomycetes in addition to those previously reported. On the basis of the NMR and mass spectra of geosmin and its acid transformation product, argosmin, tentative partial structures have been proposed for both.
A method for the control of the dissolved oxygen tension in microbial cultures
Authors: Flynn D. S. , Lilly M. D.
Published: December 2004

A method for the control of dissolved oxygen tension in growing microbial cultures is described. The apparatus consists of a motor‐driven air sparge pipe which may be lowered or raised to give a variable point of entry of the air stream into the culture liquid and hence a variable gas dispersion and gas–liquid contact time. Control of the sparge pipe position is by means of a feedback control loop consisting of a dissolved oxygen probe, an on/off controller, and a reversing electric motor which drives the sparge pipe. The difficulty presented by the relatively slow response of the oxygen probe has been overcome by incorporating an adjustable rate of control action.
A mathematical model for the batch reactor kinetics of algae growth
Authors: Ragonese Francis P. , Williams John A.
Published: December 2004

A mathematical model based on the Einstein law of photochemical equivalence is proposed to describe the batch growth of unicellular algae. The model was applied in an integrated form to cell concentration versus growth time data taken over an extended range of cell concentrations which include both the regions of “exponential” and “linear” growth. It is shown that a certain function of cell concentration contained in the integrated form of the model is linearly dependent on the growth time over both the “exponential” and “linear” growth regions.
A mathematical model for the continuous culture of microorganisms utilizing inhibitory substrates
Authors: Andrews John F.
Published: December 2004

A mathematical model is presented for both batch and continuous cultures of microorganisms utilizing inhibitory substrates. The key feature of the model is the use of a inhibition function to relate substrate concentration and specific growth rate. Simulation studies show that the primary result of inhibition by substrate in a batch culture is an increase in the lag time whereas in continuous culture inhibition by substrate may result in process instability. The model should be of value in investigations of the stability of biological processes used for the treatment of certain industrial wastes such as those containing phenols, thiocyanates, nitrates, ammonia, volatile acids, etc., which are known to be inhibitory to many of the organisms metabolizing them.
Kinetics of product inhibition in alcohol fermentation
Authors: Aiba S. , Shoda M. , Nagatani M.
Published: December 2004

The inhibitory effect of ethanol concentration p in a medium on the specific rates of growth μ and ethanol production ν of a specific strain of baker's yeast was studied in a chemostat, where except for ethanol as the product, only the concentration of glucose S was controlled to limit the metabolic activity of the yeast. This was designed to supplement the previous findings from the batch experiment, in which ethanol was added artificially and no substrate components were limiting the metabolism of the same yeast, that μ = μ0e and ν = ν0e, where k1 and k2 are empirical constants and subscript the 0 denotes respective values at p = 0. The effects of p on the values of μ and ν were confirmed by the Lineweaver‐Burk plot to belong to noncompetitive inhibition. The formulas here for μ and ν as affected by p, if extrapolated to the case of no limiting substrates, were in good agreement in respective forms with those derived previously from the batch experiment, though the values of corresponding coefficients in these formulas were different. The differential equations for μ and ν as functions of both p and S and, in addition for the rate of glucose consumption as correlated by the yield factors either with the cell growth rate or the rate of ethanol production, were solved properly with a digital computer. A kinetic, pattern calculated so far was discussed with reference to the data obtained in the batch experiment and those relevant to actual “sake” brewing.
Investigation of some methods for increasing the digestibility in vitro of microalgae
Authors: Hedenskog Gudmund , Enebo Lennart , Vendlová Jitka , Prokeš Bohumír
Published: December 2004

In order to increase the availability of the cell bound protein in Scenedesmus algae, mechanical, enzymatic, and chemical methods of degrading the cell wall structure were investigated.

Mechanical treatment involved the use of a ball‐mill. The algae suspension together with glass beads was milled in a water‐cooled chamber equipped with rotating disks. The enzyme tested was a cellulolytic enzyme (Meicelase) and the chemical employed was hydrogen peroxide.

In the ball‐mill experiments a complete disintegration was achieved ina disintegrator, working with batches. Trails wwere also performed with a continuous disintegrator and the depedence of disintegration on bead size and flow rate was studied. The disintegration determined by microscropic cell count was compared to the increase of the pepsin digestibility.

The meicelase treatment caused a slight increase of the pepsin digestibility, as measured after 3 hr pepsin incubation. No increase of the pepsin disgestibility could be detected with hydrogen peroxide treatment.

After the ball‐mill disintegration 95% of contaminating bacteria were killed and yields of extractable proteins were higher. The capacity of availble continuous ball‐mills is such that they could be used on a pilot‐plant scale and the energy cost of disintegration would be of the same magnitude as that of separation.
Studies on the relationship between specific growth rate and concentration of nitrogen source for heterogeneous microbial populations of sewage origin
Authors: Goel K. C. , Gaudy A. F.
Published: December 2004

Batch experiments were run using heterogeneous populations to determine whether a hyperbolic equation of the type suggested by Monod could be used to depict the relation between specific growth rate, μ, and NH3‐N concentration when ammonia N was the growth‐limiting nutrient. The heterogeneous populations employed were developed from sewage seed grown on glucose at various levels of nitrogen and various dilution rates in completely mixed continuous flow reactors. It was found that the hyperbolic function could be used. Values of μm in the range of 0.4–0.7 hr−1 were observed, and values of Ks, in general, ranged from 1.5 to 4.0 mg/l. Variation in the values of these growth “constants” did not follow any discernible pattern related to past growth history (i.e., COD:N ratio or dilution rate at which the cells were previously grown).
Regulation of nitrogen levels for heterogeneous populations of sewage origin grown in completely mixed reactors
Authors: Goel K. C. , Gaudy A. F.
Published: December 2004

Heterogeneous populations of sewage origin were grown continuously at, dilution rates from 1/12 hr−1 to dilute‐out (1/1 hr−1) using glucose (1000 mg/l) as carbon source and three concentrations of NH3‐N as the nitrogen source (COD:N = 70:1, 40:1, and 25:1). The effects of nitrogen level and growth rate (dilution rate) on substrate removal, biological solids production, cellular carbohydrate and protein, and NH‐N in the effluent were examined. It was found that the optimum level of nitrogen supplementation for the synthetic nitrogen‐deficient waste employed should not be based solely on the desired effluent quality with respect to COD removal but should include due consideration of reactor detention time (or dilution rate) and the allowable (or desirable) level of nitrogen leakage in the effluent.
Methylcellulose effect on cell proliferation and glucose utilization in chemically defined medium in large stationary cultures
Authors: Bryant Jay C.
Published: December 2004

Three different established strains of mammalian cells were grown in chemically defined medium in large cultures. The degree of proliferation of cells of an established strain from human skin in large stationary cultures was significantly greater in the presence of methylcellulose (medium NCTC 135M) than in its absence (medium NCTC 135). The relatively fragile cells of a derivative of monkey kidney LLCMK2 strain were carried in large stationary cultures through 11 transfer generations during 152 days. The presence of methylcellulose was associated with higher cell population levels, proliferation rates, and cell viability. Cells of this strain utilized glucose at an extremely high rate; during two representative periods the rate averaged 1.2 mg/106 cells/day in cultures on medium 135M and 1.9 mg in medium 135.

In a 53‐day experiment with mouse fibroblast 2071‐L cells, the cells in suspension culture during the first 28 days went through the normal lag, logarithmic plateau, and initial decline phases in medium 135M, and then were transferred to large stationary cultures, where they proliferated for 7 days at uniformly high rates in both medium 135 and medium 135M. It appeared that cells of strain 2071‐L in such stationary cultures had no need for Methocel as a protective agent. Glucose utilization rates while these cells were carried in large stationary cultures averaged 2–4 times the rates while they were in suspension cultures: about 0.8 and 0.2 mg/106 cells/day, repectively.
The conversion of benzyl penicillin to 6‐aminopenieillanie acid using an insoluble derivative of penieillin amidase
Authors: Self D. A. , Kay G. , Lilly M. D. , Dunnill P.
Published: December 2004

Penicillin amidase was extracted from Escherichia coli ATCC 9637, grown on phenylacetic, acid and glutamate, and purified by fractional ion with streptomycin sulphate, ammonium sulphate and polyethylene glycol, followed by chromatography on DEAE–cellulose. The purification factor was 100–200 × and the overall yield was about 115%. The enzyme was chemically attached to derivatives of cellulose and the kinetics of these insolubilized penicillin amidase preparations was investigated.
Isolation of a cyclitol antibiotic: 2,3,4,5‐tetrahydroxycyclohexanemethanol
Authors: Miller T. W. , Arison B. H. , Albers‐Schonberg G.
Published: December 2004

The isolation and structure determination of a new microbial product, (+)‐ (123/45)‐2,3,4,5‐tetrahydroxy‐1‐cyclohexanemethanol is described. This product was detected in the fermentation broth of a newly isolated actinomycete by its antibacterial activity. A novel isolation method was developed and crystalline product was obtained in good yield. The structure was determined by spectroscopic examination of the product and its acetyl and trimethylsilyl derivatives. The racemic form of this compound had already been synthezised by G. E. McCasland et. al., as analog of galactose.
Dynamic behavior of a complete‐mixing activated sludge system
Authors: Chu George C. Y. , Erickson L. E. , Fan L. T.
Published: December 2004

The dynamic behavior of a laboratory‐scale activated sludge biological waste treatment process with recycle and wasting of sludge was investigated by subjecting the system to step changes in the influent waste concentration, the recycle flow rate, or the sludge wasting rate. The dynamic behavior of the system was examined by measuring adenosine triphosphate (ATP) in addition to dissolved chemical oxygen demand (COD) and cell dry weight in the aeration tank. Cell dry weight of the recyle flow and effluent COD were also measured.

Analysis of the results and estimation of time constants assuming first order responses showed that the time constants characterizing the dynamic responses of the sludge were directly related to the sludge mean residence time. The time constants estimated from dissolved COD measurements were of the same order of magnitude as the fluid residence time in the aeration tank. The ATP transient response was frequently different from that of the cell dry weight in the aeration tank.
Maintaining perpetual synchrony in HeLa S3 culture
Authors: Thilly W. G. , Nowak T. S. , Wogan G. N.
Published: December 2004

HeLa S3 cells in suspension culture are resynchronized in each successive generation by exposure to 0.25mM thymidine. The resynchronization approach appears to be superior to single‐ and double‐block techniques because the period of effective inhibition of DNA synthesis is significantly shortened. Gram quantities of highly synchronous viable cells have been produced on a daily basis.
The rheology of mycelial broths
Authors: Roels J. A. , Van Den Berg J. , Voncken R. M.
Published: December 2004

An experimental investigation on the rheology of penicillin broths was undertaken in order to obtain more understanding of this important aspect of the fermentation process. The measuring technique consisted in observation of the torque exerted upon a rotating turbine impeller. The experimental data were interpreted in terms of a model which basically is a synthesis of a known relationship for the rheological behavior of printing ink (Casson equation) and some considerations analogous to the rheological description of polymer solutions (excluded volume concept). One of the key variables in the model is a morphology factor, which can be used for a quantitative description of mycelial morphology. The value of the morphology factor can be determined experimentally by a simple viscosity measurement in combination with a mycelial dry weight determination. There are strong indications that the model may be applicable to mycelial broths other than those of penicillin.
Experimental optimization of a step aeration waste treatment process
Authors: Chu George C. Y. , Erickson L. E. , Fan L. T.
Published: December 2004

Evolutionary operation (EVOP) was used to experimentally investigate the optimum steady state operating conditions for a step aeration activated sludge waste treatment process. A laboratory scale two tank step aeration activated sludge unit with fixed total volume, total influent flow rate, recycle flow rate, and sludge wasting rate was employed. The volume ratio and flow rate ratio which minimized effluent chemical oxygen demand were determined. The results indicate that EVOP is a useful technique for improving the performance of biological processes.
Mechanical disintegration of microorganisms in an industrial homogenizer
Authors: Mogren Hårkan , Lindblom Marianne , Hedenskog Gudmund
Published: December 2004

Disintegration of microorganisms in a continuously working industrial homogenizer has been studied. The homogenizer consists of rotating discs in a cylinder filled with glass beads. Different parameters for disintegration of baker's yeast were investigated. The disintegration process is a first‐order reaction and it is influenced by the flow rate of the suspension and by the agitator speed. At a flow rate of 200 liters/hr about 85% of the yeast cells can be disrupted in a single pass through the disintegrator. This type of disintegrator can be used for disruption of cells in order to produce single‐cell protein, active enzymes and other valuable cell components.
Immobilized enzyme reaction stability: Attrition of the support material
Authors: Regan D. L. , Dunnill P. , Lilly M. D.
Published: December 2004

One of the main reasons for immobilizing an enzyme is to enable its reuse, or continuous use, in a reactor. Consequently immobilized enzyme stability is an important factor in enzyme reactor design. The performance of the reactor will decrease if during operation the support material disintegrates into smaller particles that pass out of the reactor system.

When β‐galactosidase is immobilized by covalent attachment to AE‐cellulose, the smaller particles have a higher activity. After subjection of the immobilized enxyme to a shear stress the average particle size decreases and the total enzymic activity increases. A loss of small particles from the reactor, although constituting a small weight percent loss of support, will result in a disproportionately large loss in activity. The relevance of these observations to reactor performance is discussed.
A generalized mathematical model for the growth kinetics of Saccharomyces cerevisiae with experimental determination of parameters
Authors: Peringer P. , Blachere H. , Corrieu G. , Lane A. G.
Published: December 2004

A general model of the kinetics of microbial growth has been developed involving the kinetics of incorporation of substrate into biomass and the maintenance energy requirements.

Results obtained from batch cultures of the yeast Saccharomyces cerevisiae growing in synthetic media at pH 5.1 and 30°C permitted all biological parameters in the model to be calculated.

Values obtained for these parameters were: maximum specific glucose uptake rate (μSm), 2.08 g/g biomass/hr; apparent Michaelis constant for glucose (KS), 0.1 g/liter (5.5 × 10−4M) apparent Michaelis constant for oxygen (KL), 1.4% O2 (3.2 × 10−6 M) quantitative index of the Pasteur effect (b), 4.9 × 10−4%−1 O2 (207 M −1). Under conditions of strongly substrate‐repressed respiration the values obtained for YATP and P/O were constant over the course of the exponential phase of growth (YATP = 10.4 g biomass/mole ATP; P/O = 3 moles ATP/atom 0). Mass balances for aerobic and anaerobic cultures confirmed the results obtained form the generalized model. Results presented suggested the operation of a mechanism for regulating energy‐yielding metabolism which involved an equilibrium between the systems of oxidative phosphorylation and dephosphorylation and was dependent upon the level of catbolite repression.
Immobilization of enzymes by radiopolymerization of acrylamide
Authors: Kawashima Koji , Umeda Keiji
Published: December 2004

A new and simple method for immobilization of enzymes by the aerobic radio‐polymerization of acrylamide was developed. Irradiation treatment of acrylamide in the frozen state produces a spongy immobilized enzyme membrane without the addition of carriers. Aerobic polymerization yields of acrylamide in the frozen state were increased by the addition of starch and also by lyophilization.

Glucose oxidase (activity recovery was 12.3–33.7%), invertase (69.2%), D‐amono acid oxidase (25.0–70.5%), aminoacylase (39.2–43.7%), mold α‐amylase (18.0%), malt β‐amylase (4.1%), glucoamylase (6.5%), alkaline protease (5.3%), and neutral protease (10.5%) were immobilized by this method. Invertase entrapped by this method had a wider optium pH range and was active at higher temperatures.
Single cell proteins from cellulosic wastes
Authors: Bellamy W. Dexter
Published: December 2004

Conventional sources of protein cannot meet the present or projected needs for human consumption. Single cell proteins from fermentation of petroleum and cellulosic wastes are likely sources of additional protein. The volume of cellulosic wastes is sufficient to supply all additional protein needs on a continuing basis for cellulose is a renewable resource. Both mesophilic and thermophilic microorganisms utilize cellulose at reasonable rates. Biodegradation of lignin and lignin–cellulose complexes constitutes a major obstacle to commercial utilization of cellulosic wastes. Thermophilic actinomyces appear to be the most effective organisms for single cell protein production from cellulosic wastes.
Simultaneously immobilized glucose oxidase and catalase in controlled‐pore titania
Authors: Messing Ralph A.
Published: December 2004

The immobilization of glucose oxidase and catalase by adsorption within the pores of controlled‐pore titania has yielded a remarkably stable enzyme system. Catalase apparently acts as both a stabilizer and an activator for glucose oxidase within the pores of this material. Hydrogen peroxide concentrations and flow rates have a marked effect upon the apparent activity of the immobilized enzyme system. The carrier parameters were varied to obtain optimum loading and stability information.
CO2 mass balance in a suspension of algae cultivated in the neutral pH region of the suspension on an open cultivation surface
Authors: Lívanský K. , Prokeš B.
Published: December 2004

The CO2 mass balance for a suspension of algae cultivated in the region of neutral pH of the suspension on an open cultivation surface with a flowing suspension was assessed. From this balance an analytical expression for the course of free CO2 dissolved in the suspension along the flow of the suspension is obtained. Relations for the rate of CO2 decrease in the suspension and the utilization of CO2 supplied to the cultivation surface are derived.
Pilot scale affinity chromatography: Purification of β‐galactosidase
Authors: Robinson P. J. , Wheatley M. A. , Janson J.‐C. , Dunnill P. , Lilly M. D.
Published: December 2004

β‐Galactosidase has been purified from an ammonium sulfate precipitate of E. coli strain ML308 by biospecific adsorption on a column of agarose gel substituted with p‐aminophenyl‐β‐D‐thiogalactopyranoside. The system described using a 1.8 liter column has a useful processing capacity of 3.8 × 106 units of β‐galactosidase per 2 hr cycle. This corresponds to about 5 g of pure enzyme. An electromechanical timing device operates a set of six solenoid valves and carries out a preset program consisting of sample application, washing, and elation operations.
Large scale enzymatic synthesis of nucleoside‐5′‐monophosphates using a phosphotransferase from carrots
Authors: Marutzky R. , Peterssen‐Borstel H. , Flossdorf J. , Kula M.‐R.
Published: December 2004

The enzymatic synthesis of nucleoside‐5′‐monophosphates from purineriboside, 6‐mercapto‐purine riboside, 6‐methylmercapto‐purine riboside, 6‐chloro‐purine riboside, tubercidin, 8‐aza‐adenosine, and 3′‐deoxy‐adenosine is described in gram scale. The synthesis is catalyzed by a phosphotransferase from carrots and uses phenylphosphate as phosphate donor. The reaction products are purified on QAE‐Sephadex A25 columns. The large scale preparation of the enzyme is also reported.
Properties of ribulose diphosphate carboxylase immobilized on porous glass
Authors: Shapira Jacob , Hanson Carl L. , Lyding Judith M. , Reilly Peter J.
Published: December 2004

Ribulose‐1,5‐diphosphate carboxylase from spinach has been bound to arylamine porous glass with a diazo linkage and to alklamine porous glass with glutaraldehyde. Stability at elevated temperatures and responses to changes of pH and ribulose‐1,5‐diphosphate, Mg2+, and dithiothreitol concentrations were not significantly different from the soluble enzyme, though stability at 4°C was somewhat improved.
Grazing of ciliates on blue–green algae: Effects of ciliate encystment and related phenomena
Authors: Bader F. G. , Tsuchiya H. M. , Fredrickson A. G.
Published: December 2004

Grazing of the ciliate Colpoda steinii on the blue–green alga Anacystis nidulans has been studied in batch and chemostat type laboratory cultures. Growth of the populations, grazing of the ciliates on the algae, hydrodynamic washout of the populations (in chemostat cultures), encystment of Colpoda, and transfer of cysts from the liquid culture to the vessel wall and their attachment thereto were all found to have significant effects on the dynamics of this system. In addition, reinoculation of the liquid with ciliates excysted from the wall and with algae detached from the wall may be important. The interaction of all of these processes produces quite complex dynamical phenomena which at present cannot be predicted by a model. The results obtained differ from those found earlier for feeding of ciliates or slime mold amoebas on bacteria in that steady states of coexistence, rather than sustained oscillations, were exhibited by the present system.
Grazing of ciliates on blue–green algae: Effects of light shock on the grazing relation and on the algal population
Authors: Bader F. G. , Tsuchiya H. M. , Fredrickson A. G.
Published: December 2004

Experiments on the grazing of the ciliate Colpoda steinii on the blue–green alga Anacystis nidulans showed, among other things, that declines of the algal population initiated by grazing often continued for several days after grazing pressure had been released. In addition, long lags were observed when this alga was inoculated into sterile culture medium. Evidence presented in this study indicates that both phenomena were due to cellular damage caused by exposure of algal cells to a sudden increase of light intensity (“light shock”). The occurrence of light shock appeared to exert a destabilizing influence on the grazing relation between Colpoda and Anacystis.
Dynamics of mixed cultures of Lactobacillus plantarum and Propionibacterium shermanii
Authors: Lee Inn Hee , Fredrickson A. G. , Tsuchiya H. M.
Published: December 2004

The mixed culture of Lactobacillus plantarum and Propionibacterium shermanii grown anaerobically in glucose minimal medium exhibits features typical of a commensal interaction even though a number of complicating factors, such as a large maintenance requirement of L. plantarum and inhibition of growth of P. shermanii at low pH, are present. A simple mathematical model of the system is presented and is shown to reproduce rather well some of the features of the continuous mixed culture system in both steady‐state and transient situations.
Immobilization of tyrosinase within polyacrylamide gels
Authors: Schiller Julian G. , Liu C. C.
Published: December 2004

The enzyme tyrosinase (E.G. 1.14.18.1) has been immobilized in a polyacrylamide gel and intermittently assayed for enzyme activity over a period of 19 days using phenol as the substrate. The results of these studies indicate that the immobilized enzyme could be incorporated into a system to detect phenol and related compounds that are found in industrial effluents and as surface water contaminants.
A simple device for stationary cultivation of microorganisms
Authors: Kybal Jan , Vlček Vladislav
Published: December 2004

A new device is designed that is suitable for both laboratory‐ and industrial‐scale cultivation of microorganisms, particularly filamentous fungi, on the surface of liquid media. The device reliably ensures the sterility of cultivation, regardless of its duration. Its installation costs are relatively low and maximum production is reached per unit of installation space. In comparison with submerged cultures in fermentors, the proposed mode does not use a high consumption of energy for stirring and aeration (consequently, the duration of cultivation is not an economically relevant factor) and does not require maintenance of complicated equipment. Due to the building and construction of the technological equipment, the production plant is capable of very fast expansion and, when the need arises of very fast and economical liquidation.