bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on cyclic peptides. IV. Conformation of cyclo(Sar‐Sar‐Gly)2, cyclo(Sar)6 and cyclo(Sar‐Gly‐Gly)2 and their conformational change induced by alkali thiocyanates
Authors: Sugihara Toshiharu , Imanishi Yukio , Higashimura Toshinobu
Published: December 2004

Conformation of cyclo (Sar‐Sar‐Gly)2, cyclo(Sar)6, and cyclo(Sar‐Gly‐Gly)2 was investigated by nmr spectroscopy. cyclo(Sar‐Sar‐Gly)2, were shown to assume various conformations in dimethysulfoxide. It was attributed to the distribution of cis as well as trans Gly‐Sar or Sar‐Sar amide links along the peptide backbone. In particular, cyclo(Sar‐Sar‐Gly)2 took five or six different conformations: one or three C2‐symmetric conformations and four or three asymmetric conformations, respectively. Three of nine NH resonance signals were ascribed to the internally hydrogen‐bonded glycine residues. cyclo(Sar‐Sar‐Gly)2 and cyclo(Sar)6 showed a spectral change on the addition of alkali thiocyanates, indicating a conformational change induced by a complex formation with the alkali cations. The complex nmr spectrum due to a hybridization of different conformations changed with the salt addition into a simple nmr spectrum, suggesting a preponderence of a new, single conformation. On the basis of the spectral change, the strength for the cations binding the cyclic peptides was found to be in the order of K+ > Na+ > Rb+ > Cs+ for cyclo(Sar‐Gly‐Gly)2 and K+ > Rb+ > Cs+ for cyclo(Sar)6. On the other hand, cyclo(Sar‐Gly‐Gly)2 in dimethylsulfoxide assumed a single C2 conformation having two glycyl peptide protons shielded from solvent and the other two exposed to solvent. This conformation did not change with the salt addition. Finally, the conformations of several cyclic peptides containing the sarcosine residue such as cyclo(Sar)6 cyclo(Sar‐Sar‐Gly)2 cyclo(Pro‐Sar‐Gly)2, and cyclo (Sar‐Gly‐Gly)2 were compared. It appeared that proline and glycine residues reduced the conformational multiplicity of the cyclic peptide backbone, and the ability to bind alkali metal cations decreased in the above order.
Binding of water and electrolytes to proteins. An equilibrium dialysis study
Authors: Bull Henry B. , Breese Keith
Published: December 2004

The technique of equilibrium dialysis has been used to study water and salt binding to egg albumin, to human carbon monoxide hemoglobin, and to bovine serum albumin. The salts used were CsCl, KCl, NaCl, LiCl, Gu·HCl, NaBr, Cs2SO4, K2SO4, Na2SO4, Li2SO4, and Gu2SO4. The amount of water bound by proteins depends on the probe being used. Sulfates tend to bind to proteins and they also increase the water binding. At saturation, about 41 and 140 mol Gu·HCl bind to 1 mol egg albumin and to 1 mol carbon monoxide hemoglobin, respectively. Both proteins are dehydrated by Gu·HCl.

The hydrodynamic hydration of egg albumin as determined by viscosity appers to increase as the relative viscosity of the medium increases.
N‐methylleucine gramicidin‐S and (di‐N‐methylleucine) gramicidin‐S conformations with cisL‐Orn‐L‐N‐MeLeu peptide bonds
Authors: Patel Dinshaw J. , Tonelli Alan E.
Published: December 2004

Conformations containing all trans peptide bonds have previously been proposed for N‐methylleucine gramicidin‐S and (di‐N‐methylleucine) gramicidin‐S based on an evaluation of proton nuclear magnetic resonance parameters in a series of solvents. These gramicidin‐S derivatives exhibit full biological activity despite the fact that the proposed solution conformations differ in backbone topology and relative orientation of the Phe and Orn side chains compared to gramicidin‐S. The present authors discuss conformations for N‐methylleucine gramicidin‐S and (di‐N‐methylleucine) gramicidin‐S which incorporate cis peptide bonds at L‐Orn‐L‐N‐MeLeu, where the gramicidin‐S backbone is essentially retained, and the relative orientation of the Pro, Orn, Val, and Phe side chains correspond to those observed for gramicidin‐S. A novel hydrogen‐bond arrangement involving one carbonyl group interacting with two peptide protons (1 ←4 and 1 ←5 types) is proposed to stabilize the backbone conformation in the gramicidin‐S derivatives. A recent report on the cyclic heptapeptide antibiotic, Ilamycin B1, shows the presence of cis peptide bonds at N‐CH3 amino acids, as well as the novel hydrogen‐bond arrangement presented above.
Synthetic peptides as probes for conformational preferences of domains of membrane receptors
Authors: Naider Fred , Khare Sanjay , Arshava Boris , Severino Beatrice , Russo Joe , Becker Jeffrey M.
Published: December 2004

Peptide models have been widely used to investigate conformational aspects of domains of proteins since the early 1950s. A pioneer in this field was Dr. Murray Goodman, who applied a battery of methodologies to study the onset of structure in homooligopeptides. This article reviews some of Dr. Goodman's contributions, and reports recent studies using linear and constrained peptides corresponding to the first extracellular loop and linear peptides corresponding to the sixth transmembrane domain of a G‐protein coupled receptor from the yeast Saccharomyces cerevisiae. Peptides containing 30–40 residues were synthesized using solid‐phase methods and purified to near homogeneity by reversed phase high performance liquid chromatography. CD and NMR analyses indicated that the first extracellular loop peptides were mostly flexible in water, and assumed some helical structure near the N‐terminus in trifluoroethanol and in the presence of micelles. Comparison of oligolysines with native loop residues revealed that three lysines at each terminus of a peptide corresponding to the sixth transmembrane domain of the α‐factor receptor resulted in better aqueous solubility and greater helicity than the native loop residues. © 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2005
Conformational aspects of polypeptide structure XVI. Rotatory constants, cotton effects, and ultraviolet absorption data for glutamate oligomers and co‐oligomers
Authors: Goodman Murray , Rosen Ira G.
Published: December 2004

We have reinvestigated the stereochemistry of a series of L‐glutamate oligomers, preparing the peptides mainly via the azide route rather than the p‐nitrophenyl ester method. Our results are in agreement with our previously published studies. Both investigations relied on derived rotatory dispersion constants b0 and λc, ultraviolet spectra in the 190 mμ range, and molar rotation data. Our measurements have now been extended to include the 233 mμ Cotton effect region. This paper also includes a study of the solvents, 2,2,2‐trifluoroethanol and hexafluoroacetone “trihydrate.” Both solvents are transparent in the far ultraviolet region. The former is a solvent supporting helical structures in glutamate oligomers above the heptamer. The latter solvent does not support secondary structure for any of the oligomers studied. We have treated our data for b0 and Cotton effect rotations in terms of molar quantities. We use the additivity principle and plot molar b0 or 233 mμ molar rotations against the number of residues in the oligomer chain. We are able to relate the changes in the slopes of the straight lines to the onset of helicity and the actual magnitudes of the slopes to the high polymer residue values. Co‐oligomers of glutamic‐aspartic acid form secondary structures of the glutamate type while glutamic acid‐glycine co‐oligomers show very little secondary structure. Finally, hexafluoroacetone “trihydrate” supports stable helices for several high polymers but denotes weak helices in polymer systems.
Energy levels of almost‐periodic polymers
Authors: Herzenberg A. , Modinos A.
Published: December 2004

Numerical calculations have been done on the exciton spectrum of a schematic model of a linear polymer. The model consists of a random sequence of two kinds of subunit whose energy levels and transition moments are almost, but not quite, the same. The orders of magnitude of parameters are taken from DNA, but the full helical geometry has not been considered. Results are given for the density of energy levels, the dipole transition strength per unit energy, and the distribution of excitation energy along the polymer in individual states. A number of localized exciton states were found.
Viscosity study of DNA
Authors: Scruggs Robert L. , Ross Philip D.
Published: December 2004

The intrinsic viscosity of DNA (salmon sperm, calf thymus, T4 phage) in the presence of univalent cations decreases in a continuous manner as the ionic strength is increased and then attains a characteristic limiting value for each cation. Between 0.1 and 0.5M the intrinsic viscosity is independent of cation, while at high salt concentration the order of decreasing limiting viscosity is K+, Na+, Li.+ The intrinsic viscosity of T4 bacteriophage DNA decreases with increasing Mg++ concentration and in 0.1M MgCl2 attains a value one‐half of that found in 0.2M NaCl. Slightly beyond 0.1M MgCl2 spontaneous growth of birefringent fibers takes place, and upon further addition of Mg++ these fibers redissolve to form a transparent gel of higher viscosity. The observed Huggins' constants pass through a maximum with increasing salt concentration for all of the ions studied. It is demonstrated that the concentration dependence of the reduced viscosity may be abolished and regenerated by the introduction and removal of trace amounts of basic proteins, polypeptides and polyamines. The viscosity behavior observed with the deliberately contaminated DNA samples resembles most of that reported in earlier viscosity studies, indicating that a large body of previous work on DNA probably was performed on impure material.
Polymerization of N‐carboxyanhydrides of 1‐aminocycloalkanecarboxylic acids
Authors: Frankel Max , Bachi Mario David
Published: December 2004

The polymerizations of the N‐carboxyanhydrides of 1‐aminocyclopropanecarboxylic acid, 1‐aminocyclobutanecarboxylic acid, 1‐aminocyclopentanecarboxylic acid, and 1‐aminocyclohexanecarboxylic acid were investigated. These N‐carboxyanhydrides did not polymerize in bulk when heated to their melting points under reduced pressure. In solution, they polymerized extremely slowly on initiation with n‐hexylamine and relatively slowly when initiated by sodium methoxide–methanol. The polymerization rates of the above NCAs in dimethyl sulfoxide solution, initiated by sodium methoxide–methanol were found to increase in the following order: NCA of 1‐aminocyclohexanecarboxylic acid, NCA of 1‐aminocyclopropanecarboxylic acid, NCA of 1‐aminocyclopentanecarboxylic acid and NCA of 1‐aminocyclobutanecarboxylic acid. The influence of the alicyclic side rings on the relative rates of polymerization of the respective NACs is considered.
Crosslinked synthetic polypeptides. II. Evaluation of the internal structure of intramolecularly crosslinked polymers by polarization of fluorescence measurements
Authors: Gill Thomas J.
Published: December 2004

The introduction of intramolecular amide bonds into synthetic polypeptides produces molecules with organized spatial structure which are good models for the tertiary structure of proteins. Polarization of fluorescence measurements were used to study the internal structure and the overall rigidity of the intramolecularly crosslinked polypeptides. The graph of [(1/p) + (1/3)] against T/η changes from a straight line to a continuous curve: the temperature at which this change occurs and the slope of the straight line segment measure the stability of the internal structure of the molecule. The introduction of one to six crosslinks produces an organized internal structure that becomes more stable as the number of crosslinks increases. In contrast to the fluorescence measurements, the intrinsic viscosities, reflecting the overall hydrodynamic domain of the molecules, change (decrease) to the same extent whether one, four, or six intramolecular crosslinks are present. The overall rigidity of the polymers can be assessed by the rotational relaxation time ρh and the polarization at 10°C. p10. Both of these criteria show that the presence of six crosslinks significantly increases the rigidity, but one or four does not. The various hydrodynamic measurements may be fitted into a hierarchy of discrimination: intrinsic viscosity, sedimentation, and diffusion for size and shape; rotational relaxation time and polarization of fluorescence at a given temperature for overall molecular rigidity; and transition temperature and rate at which it is attained for internal molecular detail.
Determination of the dominant factors which influence the net hydration of native sodium deoxyribonucleate
Authors: Hearst John E.
Published: December 2004

A theory for the dependence of the net thermodynamic solvation of a macroion in an electrolyte solution is presented. The solvation in moles salt/mole macroion is shown to approach – |Zp|/v in the limit of infinite dilution of salt and macroion. The solvation in moles water/mole macroion is shown to approach zero at zero water activity. Isopiestic determinations of the hydration of sodium deoxyribonucleate in NaCl, Na2SO4, and NaClO4 solutions indicate that short‐range interactions of the NaDNA with solvent account for more than half of the observed solvation. The net hydration appears to be predominantly influenced only by water activity.
Interactions of metal ions with polynucleotides and related compounds. III. Degradation of polyribonucleotides by lanthanum ions,
Authors: Eichhorn Gunther L. , Butzow James J.
Published: December 2004

The polyribonucleotides of adenylic, cytidylic, and uridylic acids are degraded in a 2‐hr. period at 64°C. into low molecular weight oligonucleotides and mononucleotides through the action of lanthanum (III) or other trivalent inner transition metal ions. Polyinosinic acid is degraded somewhat more slowly. Cleavage of the polynucleotide chains occurs at the 5′‐phosphate linkages. The 3′‐mononucleotides produced require over 100 hr. of further heating at 64°C. to produce nucleoside and orthophosphate. The reaction between lanthanum (III) and the polynucleoside involves one metal ion for every three nucleotide residues, with each metal ion apparently chelated to a 2′‐hydroxyl and a phosphate group and bound to only one polynucleotide chain.
Interactions of metal ions with polynucleotides and related compounds. IV. Degradation of polyribonucleotides by zinc and other divalent metal ions,
Authors: Butzow James J. , Eichhorn Gunther L.
Published: December 2004

Polyadenylic acid is degraded into mononucleotides and low molecular weight oligonucleotides in a 20 hr. period at 64°C. by the action of Mn (II), Co (II), Ni (II), and Cu (II) ions, and in a 2 hr. period by Zn (II) ions. The latter also degrade poly C, poly U, and RNA at approximately the same rate, but poly I is degraded very much more slowly. No such difference in reaction rates can be observed in the alkaline degradation of polynucleotides. The sluggishness of the reaction with poly I is not due to any highly ordered structure of the zinc–poly I complex, but probably to the weakening of the zinc–phosphate bond through simultaneous binding of the zinc to the inosine base. Evidence for such a hypothesis is derived from the inhibition of the zinc degradation of poly A by inosinic acid or poly I. No drastic difference in the nucleotide composition of the undegraded residue can be observed in the degradation of RNA by zinc and by alkali.
Conformation of polyriboadenylic acid: pH and temperature dependence
Authors: Holcomb D. N. , Tinoco I.
Published: December 2004

Evidence is presented that polyriboadenylic acid (Poly A) is a single‐strand flexible helix of stacked bases at neutral pH and room temperature. As the temperature is raised the stacking decreases, but there is still perceptible order at 80°C. The thermal transition from the double‐strand helix (which exists at low pH) to the single‐strand helix has been followed by optical rotatory dispersion, optical absorption, and viscosity measurements.
Theoretical determination of sterically allowed conformations of a polypeptide chain by a computer method
Authors: Némethy George , Scheraga Harold A.
Published: December 2004

A mathematical method has been developed, together with a digital computer program for its evaluation, for the determination of possible conformations of a polypeptide chain for any given amino acid sequence. Allowed conformations were required to satisfy predetermined criteria regarding the locations of potential energy minima for rotation around single bonds, steric restrictions arising from van der Waals contacts between atoms, and the formation of a closed polypeptide loop by means of a peptide linkage or a disulfide bridge. Requirements for specific noncovalent interactions can also be considered. Various assumptions regarding the selection of the minima for rotational potentials and of the van der Waals contact distances are discussed. According to the assumptions adopted in the paper, 21 conformations are allowed for a glycine residue which is part of a dipeptide. These conformations are assumed to lie at minima of the rotational potential function, and satisfy simultaneously the steric requirements. Dipeptides containing alanine or other residues are restricted to 7 such conformations. As an example of the applicability of the method, the computation was performed for the smallest loop containing a disulfide bridge in the ribonuclease molecule, i.e., the cyclic octapeptide formed by residues 65 to 72. Only 15 allowed conformations were found for the loop as a whole. Parameters characterizing these allowed conformations are tabulated. Approximate calculations indicate the importance of steric restrictions and of the presence of side chains in reducing the conformational freedom of this peptide. Further potentialities of the method are discussed.
Kinetics and equilibria in the acid denaturation of deoxyribonucleic acids from various sources
Authors: Bunville L. G. , Geiduschek E. P. , Rawitscher M. A. , Sturtevant J. M.
Published: December 2004

The acid denaturation of a variety of DNA‡ samples with guanine–cytosine (GC) contents ranging from 37–64% has been investigated by means of potentiometric, spectrophotometric, and thermal titrations, including spectrophotometric titrations in a stopped‐flow fast reaction apparatus. As the pH of a solution of native DNA is lowered from the neutral range the net charge on the molecule becomes more positive as a result of the addition of protons to the bases adenine, cytosine, and to a lesser extent guanine. At a fairly sharply defined value of the charge a conformational transition sets in which is completed after the charge has increased in the positive direction by an additional 0.4–0.5 unit per base pair. The threshold value of the charge is dependent on the composition of the DNA as well as various experimental parameters such as temperature and ionic strength. At 25°C. in 0.1M NaCl the threshold value is approximately 0.55 charge unit per base pair relative to pH 6 for a GC content of 37% and 0.78 for 64% CG. The conformational transition is accompanied by heat absorption amounting, in the case of salmon DNA in 0.1M NaCl, to 3020 ± 150, 4920 ± 200, and 5700 ± 250 cal./mole of base pairs at 5, 25, and 45°C., respectively. If it is assumed that the heats of ionization of the bases are the same in denatured DNA as in the isolated nucleotides, the result at 25° C. can be corrected by using previously determined heats of ionization to give for the hypothetical process, DNA (native, pH 6) → DNA (denatured, pH 6) ΔH = 8300 cal./mole of base pairs. ΔH appears to be independent of DNA composition, an average value of 8000 cal./mole of base pairs being obtained for DNA samples having GC contents ranging from 37–64%. The calorimetric results are consistent with the view that hydrophobic interactions are important in the stabilization of the DNA double helix. The kinetics of the acid denaturation of salmon DNA is complex.
Interactions between trinucleotides: The electrostatic contribution and its possible relation to the mechanism of translation of the genetic code
Authors: Nash H. A. , Bradley D. F.
Published: December 2004

The coulombic interaction between pairs of trinucleotides has been computed from quantum theory. The results are discussed in terms of their relation to hydrogen bonds and stacking in such systems and to the mechanism by which messenger RNA codons recognize transfer RNA nodocs.
Effect of different solvent systems on the aggregation and conformation of S‐carboxymethyl bovine serum albumin
Authors: Harrap B. S. , Woods E. F.
Published: December 2004

The aggregation properties of S‐carboxymethyl bovine serum albumin (SCM‐BSA) have been shown to be greatly influenced by the presence of thioglycollide esters in the thioglycollic acid used as a reducing medium. Pure thioglycollic acid gives a product which is aggregated at both pH 7 and 9. Disaggregation may be effected by sodium dodecyl sulfate, by covalently linking groups on to the molecule in order to increase the net negative charge, and solvents such as 8M urea, 14M formamide, 11.5M acetic acid, formic acid, and 2‐chloroethanol. The mechanisms underlying disaggregation in these widely differing solvents are discussed. The results confirm previous findings of a single polypeptide chain in serum albumin. The optical rotatory dispersion of BSA and SCM‐BSA have been compared in a variety of solvents. It has been shown that the disulfide crosslinks in BSA are not the limiting factor to α‐helix formation.
Conformation changes in the nonionizable water‐soluble synthetic polypeptide poly‐N5‐(3‐hydroxypropyl) ‐L‐glutamine
Authors: Lupu‐Lotan Noah , Yaron Arieh , Berger Arieh , Sela Michael
Published: December 2004

Poly‐N5‐(3‐hydroxypropyl)‐L‐glutamine (PHPG) samples of molecular weights from 20,000 to 140,000 were synthesized by the action of 3‐amino‐1‐propanol on poly‐γ‐benzyl‐L‐glutamate. PHPG is freely soluble in water and in a variety of organic solvents and was shown to be devoid of functional groups ionizing in the pH range 2–12. From hydrodynamic data (viscosity, sedimentation, diffusion) and optical rotatory measurements (ORD in the range 289–650 mμ, circular dichroism and Cotton effects in the range 210–280 mμ) on samples of different molecular weight it was concluded that PHPG is largely helical in methanol, ethylene glycol, formamide, dimethylform‐amide, n‐butylamine, and acetic acid, and randomly coiled in dichloroacetic acid and formic acid. In water the polymer is partly helical, the degree of helicity increasing with decreasing temperature and increasing molecular weight. The following solutes were found to decrease the helicity in the order indicated: NaOH > guanidinium chloride > urea > HCl > LiBr > NaBr > NaCl > H2O. Detergents do not destroy the helical conformation. Helix–coil transition curves were obtained for the solvent pairs: methanol–water, acetic acid–water, and chloroform–dichloroacetic acid. Thermal transitions were observed in water, water–methanol (70:30 v/v), and dichloroacetic acid–ethylene dichloride (22:78 v/v), the latter being of the “inverted” type. Heats of helix formation were calculated and their significance is discussed.
Electrochemical observations in microbiological processes. Growth of Thiobacillus thiooxidans. I
Authors: Fischer David J. , Herner Albert E. , Landes Alma , Batlin Alex , Barger John W.
Published: December 2004

The growth of Thiobacillus Thiooxidans, utilizing sulfur in three media, was studied by observing changes in halfcell emf, bacterial cell count, and acid production, all as a function of time. A comparison of the biological halfcell emf with comparable control halfcells reveals that T. thiooxidans makes an electrochemical contribution to halfcell voltage. A change from the more complex medium of Skerman's mineral salts to ATCC allowed a clearer delineation of the ability of T. thiooxidans to make an electrochemical contribution. Reproducible biological halfcell emf's were obtained when the ferrous sulfate was removed from the ATCC medium. One halfcell, consisting of T. thiooxidans utilizing sulfur in ATCC, was observed over a 111‐day period. During this time, the initial halfcell voltage of −0.35 V. decreased to a value of −0.64 V. (hydrogen emf series). T. thiooxidans, in utilizing sulfur, produces only sulfate ion, thereby simplifying the identification of an electrochemical contribution during growth.
Electrochemical observations in microbiological processes. Growth of Thiobacillus Thiooxidans. II
Authors: Fischer David J. , Landes Alma , Sandford Maxwell T. , Herner Albert E. , Wiegand C. J. Wesley
Published: December 2004

The electrochemical activity of the individual chemicals in the nutrient medium for growth of Thiobacillus thiooxidans was studied along with the effect of the gases in equilibrium with their solutions. Several chemicals were active individually; however, the magnitudes, as measured by changes in half‐cell potential, were less than that observed when T. thiooxidans was present in their composite mixture. Sterilized Skerman's mineral salts and the American Type Culture Collection (without ferrous sulfate) media were not sensitive electrochemically to changes from pure oxygen to nitrogen atmospheres. When T. thiooxidans was present in these media, the biological half‐cell emf became sensitive to changes in the oxygen content of the atmosphere in equilibrium with the organism and nutrient. The ability of T. thiooxidans to make an electrochemical contribution, as registered by a platinum electrode, is substantiated further by these investigations.
Gas absorption in a stirred vessel: Locale of transfer action
Authors: Wilhelm R. H. , Donohue W. A. , Valesano D. J. , Brown G. A.
Published: December 2004

By means of gas‐absorption experiments in a stirred vessel, with various depths of liquid above a properly positioned single‐opening pipe‐type gas sparger, conclusions are reached about relative contributions to the overall absorption rate by localized actions near the sparger tip, in the impeller region, and from bubbles distributed in the bulk volume of the fluid. Results are discussed for difficulty soluble gases (oxygen in water and chlorine in water) and a substantially soluble gas (chlorine in benzene). In all cases, dissolution rates in the vicinity of the sparger and impeller were significantly large compared with those near free bubbles.
Oxygen‐absorption rate‐controlled feeding of substrate into aerobic microbial cultures
Authors: Hospodka Jaroslav
Published: December 2004

A system of automatic control of substrate inflow into an aerated culture of microorganisms which depend on oxygen‐absorption rate (OAR) has been devised and tested. As the control variable, dissolved oxygen concentration (DOC), which shows the equilibrium between OAR and oxygen‐uptake rate in the microbial culture, was chosen. If the equilibrium is disturbed by changes in OAR, then the oxygen‐uptake rate is changed by substrate limitation. The DOC is measured by means of a Clark‐type polarographic electrode, and the signal is used to actuate the substrate inflow valve or pump. The oxygen‐uptake rate changes of microorganisms, after the addition or exhaustion of substrate in the medium, are so rapid that they can be used for this type of control.

Fundamental equations were derived and graphical solutions for the control system parameters were suggested for the steady‐state relations between DOC, oxygen‐uptake rate, specific growth rate, substrate concentration, KLa, and concentration of microorganisms. The system is stable in the entire range of the uptake rates up to nearly the maximum attainable in unlimited substrate conditions, and can be operated in batch feed or continuous flow modifications. It was experimentally tested with the yeast Saccharomyces cerevisiae. The complete utilization of aeration‐system capacity of the fermentor was achieved with high yeast yield and no alcohol formation. The quality of the product was excellent.
Microflotation: New low gas‐flow rate foam separation technique for bacteria and algae
Authors: Rubin Alan J. , Cassel E. Alan , Henderson Oliver , Johnson J. Donald , Lamb James C.
Published: December 2004

Foam separation of microorganisms has been investigated with varying success by many workers, usually at high rates of gas flow. Microflotation was developed to overcome some of the disadvantages inherent in these high gas‐flow‐rate processes and is introduced in this paper as a new technique for the foam separation of microorganisms at low gas‐flow rates. With microflotation, a stable surface phase is produced by adding an insoluble collector such as a long‐chain fatty acid or amine. The formation of an insoluble surface phase eliminates the need for high foaming. Low rates of gas flow are used resulting in a more efficient separation and a less voluminous and drier surface phase upon which to collect the microorganisms. The efficiency of this technique is also improved by using flotation aids such as frothers and flocculents. Frothers are used to improve the collector properties of the surfactant and to refine further the small bubbles produced by a very fine sparger. Small concentrations of flocculents, such as alum, are used to partially agglomerate the organisms and provide sites for adsorption of collector. The work described in this paper is preliminary in nature, designed to illustrate that a low flow‐rate process may be used to separate microorganisms and to stimulate further research. The applications discussed are removal of the bacterium, Escherichia coli, and alum, and two species of algae, Chlamydomonas reinhardtii and Chlorella ellipsoidea, using stearylamine without alum. The frother used was ethanol.
Sterilization of tissue‐culture medium by filtration on a large laboratory scale
Authors: Telling R. C. , Stone C. J. , Maskell M. A.
Published: December 2004

The design and operation of a permanently‐piped plant for sterilizing 10–200 l. of tissue‐culture media is described. The plant is sterilized in situ by steam injection, the filtration rate is 2–3 l./min., and the turn‐around time for volumes of 100 l. is about 3 hr.
Characteristics of hydrogen bacteria
Authors: Repaske Roy
Published: December 2004

A brief review of the development of our knowledge about hydrogen bacteria is presented, with emphasis on the characteristics and physiological differences of various Hydrogenomonas species. One species, Hydrogenomonas eutropha, is discussed in greater detail. Nutritional requirements, physical factors affecting growth, and equipment used for culturing 100‐ml. shake cultures and 15‐1.mass cultures of H. eutropha are described. Cell‐free extracts of H. eutropha carry out the oxyhydrogen reaction as demonstrated by the alternate reduction and oxidation of endogenous flavins and cytochromes by molecular hydrogen and oxygen, respectively. Spectra of cell‐free extracts of this organism show the presence of cytochromes of the c and b1 types. A cytochrome of the o type was also found, but none of the a cytochromes were detected. The sum of a series of enzymatic reactions shown to be catalyzed by these extracts can account for the oxidation of hydrogen by oxygen.
A chemically defined fermentation medium for the growth ofMicromonospora purpurea
Authors: Wagman G. H. , Weinstein M. J.
Published: December 2004

A chemically defined medium forMicromonospora purpureahas been devised, consisting of glucose, a nitrogen source, calcium carbonate, magnesium sulfate, dibasic potassium phosphate, and the required trace quantities of iron, copper, zinc, and manganese. Using washed cell inocula, dry mycelial weights of more than 16 mg./ml. were obtained in 7‐day shaken‐flask fermentations. Nutrient requirements forM. purpureaare discussed and growth data presented. Sucrose, maltose, starches and dextrins could be substituted for glucose, and resulted in good growth of the organism. A number of amino acids and inorganic nitrogen‐containing compounds were capable of utilization as sole nitrogen sources. Weekly serial transfers of the culture in defined medium have shown no diminution in mycelial weights over a four‐month period.
Aeration is submerged fermentation
Authors: Brandl E. , Schmid A. , Steiner H.
Published: December 2004

Observations on quantitative relationships between oxygen diffusion rate and product formation were made with penicillin, bacitracin, and gluconic acid. For penicillin and gluconic acid formation, no toxic oxygen concentration could be achieved in the broth, whereas concentration above approximately 7 mg. O2/l. suppressed the bacitracin yield to an ever increasing extent. The intensity of mixing was measured by means of distributing a dye. With penicillin formation as an example, it was shown that the antibiotic yield is not only dependent on maintenance of a certain oxygen diffusion rate, but also on ensuring a necessary minimal mixing.
Aeration of concentrated activated sludge
Authors: Stiefel Robert C. , Washington Donald R.
Published: December 2004

A multiphase project has been planned to develop a new biological process capable of economically treating high BOD wastes. Herein is presented the results of the first phase of the program, in which the feasibility of growing concentrated microbial cultures was investigated and the oxygen and power requirements for maintaining such cultures were determined. An example is given of the scale‐up of power requirements for oxygen transfer in a prototype system.
Gas monitor and control unit for cell culture system
Authors: Harrish George , Mount David T. , McLimans William F. , Tunnah Kenneth , Scheele Steven , Moore George E.
Published: December 2004

The Meta‐Stat gas monitor, a component instrument which automatically monitors and controls the pH and gas content of the liquid phase in suspension cell‐culture systems, has been developed to provide continuous pH control within ± 0.015 units, as well as continuous oxygen control within 0.5% of the preset level in the range of 0–40% O2.
Fermentation of methane
Authors: Wolnak B. , Andreen B. H. , Chisholm J. A. , Saadeh M.
Published: December 2004

From soil and from the plant Elodea, we have isolated an organism which has not, yet been identified; it is a comparatively large Bacillus, which thriven in a medium of mineral salts saturated with a gaseous mixture of 40%, methane (or natural gas), 40% oxygen, 15% nitrogen, and 5% carbon dioxide. The isolated cells have amino acid and vitamin contents comparable to, or, in some cases greater than, those found in such nutrients as yeast, fish meal, or milk solids.
Equipment for hydrocarbon fermentations
Authors: Blakebrough N. , Shepherd P. G. , Nimmons I.
Published: December 2004

Although air‐lift fermentors have been employed industrially and in the laboratory, little information has been published on the effects of design on performance. With respect to both liquid circulation and mass transfer, not only the actual rates but the efficiency in relation to power consumption is strongly influenced by lift height and diameter, submergence ratio, and air‐flow rate. Relatively wide tubes, operating at high submergence ratios and rather low air‐flow rates favor high efficiency. Since these conditions lead to rather low absolute values of circulation and mass‐transfer rates, the microbial population which can be supported will also be rather small. Mass transfer can be increased by the insertion of an orifice some distance; above the air‐inlet point and by suitable arrangement of the discharge from the air lift into the headspace of the fermentor.
Dynamics of microbial propagation: Models considering inhibitors and variable cell composition
Authors: Ramkrishna D. , Fredrickson A. G. , Tsuchiya H. M.
Published: December 2004

Mathematical models for microbial growth in batch and continuous cultures are formulated. The models have been referred to as distributed models since the microbial population in a culture is looked upon as protoplasmic mass distributed uniformly throughout the culture. Growth is regarded as the increase in this mass by conversion of medium components into biological mass and metabolic products. Two sets of models have been presented. The first arise from introducing additional considerations into the model proposed by Monod to account for the stationary phase and the phase of decline in a batch culture. These have been referred to as unstructured, distributed models since they do not recognize any form of structure in the protoplasmic mass. The models in the second set are referred to as structured, distributed models. Structure is introduced by considering the protoplasmic mass to be composed of two groups of substances which interact with each other and with substances in the environment to produce growth. The structured models account for the dependence of growth on the past, history of the cells; thus they predict all growth phases observed in batch cultures, whereas the unstructured models do not predict a lag phase. The full implications of the models for continuous propagation, as determined by the method of stability analysis and transient calculations, are discussed. The models prediet a number of new results and should be confronted with experiments.
Submerged acetification of a vinegar base produced from waste pineapple juice
Authors: Richardson K. C.
Published: December 2004

Submerged acetification experiments were performed to determine conditions necessary for the production of a satisfactory vinegar from waste pineapple juice using a pure culture inoculum. Vinegars containing up to 7%, by weight of acetic acid could be produced in less than 24 hr. with a conversion efficiency greater than 90% in both laboratory and pilot plant equipment. None of the bacterial nutrients added to the juice improved either the rate of production or the yield of acetic acid. Oxygen transfer during the process is discussed.
The motion of liquid inside a closed vibrating vessel
Authors: Nyborg W. L. , Rodgers A.
Published: December 2004

Studies are made of the behavior of liquid contents in a closed cylindrical vessel vibrated vertically along its axis. The situation is one which had been investigated by Rodgers and Hughes (1960) because of applications in microbiology and biochemistry. By use of motion pictures it was found that surface waves develop, sonic fog is produced, and air bubbles are formed at the onset of the motion. Bubbles then move downward until, under conditions of practical interest, air is divided equally between top and bottom of the vessel. Steady‐state vertical oscillation of the central liquid body then ensues, superposed on turbulent action of air–water mixtures at the top and bottom of the vessel. Reference is made to available theory for surface wave excitation, and bubble migration. A nonlinear differential equation is considered for the steady‐state oscillation.
Production of Semliki Forest Virus from hamster kidney cells in deep culture vessels
Authors: Telling R. C. , Radlett P. J. , Mowat G. N.
Published: December 2004

The growth of Semliki Forest Virus in stirred culture vessels at volumes of 4 and 301. is described. Virus can be produced on a large scale in deep culture using industrial type vessels. Control of pH within close limits is important for maximum production of infective virus. With the parent, strain of SFV, virus yields were found to be influenced by an interference phenomenon which was apparently not due to interferon. Growth of a cloned strain of SFV obtained by serial selection of large plaques was not affected by this phenomenon. The cloned strain, when inoculated at a cell/virus input ratio of 1:1, gave maximum virus titers of 1010 p.f.u./ml., indicating an average yield of 10,000 p.f.u/BHK cell.
Traditional fermented foods
Authors: Hesseltine C. W. , Wang Hwa L.
Published: December 2004

For centuries, diverse plant and animal materials have been fermented by various bacteria, yeasts, and fungi to make excellent foods. The kinds of micro organisms used in traditional fermentation are restricted to a relatively few genera, including Aspergillus, Rhizopus, Mucor, Actinomucor, Monascus, Saccharomyces, Neurospora, Acetobacler, Bacillus, and Lactobacillus. The two principal advantages of food fermentations over other processes are to add flavor and to prevent spoilage. Fermented fish is a common food in the Orient and may have been the first product made by fermentation. Flavor is especially important in vegetable diets based on bland foods such as rice. Shoyu is the best, known oriental food fermentation, and it is very widely used as a flavoring agent. Be sides this fermentation, there are a large number of additional ones not so well known outside the Orient, whose products serve as seasoning or flavoring agents. Miso and natto are prepared from soybeans in Japan. Sufu is a cheese like product made from soybean milk in China. Tempeh and ontjom are Indonesian foods prepared from soybeans and peanuts, respectively. These food fermentations are discussed with emphasis on how they are produced and the flavor formed.
Self‐priming aerator and mechanical defoamer for microbiological processes
Authors: Ebner H. , Pohl K. , Enenkel A.
Published: December 2004

The design and operational characteristics of a sell‐priming aerator are described. The aerator works without a compressor. H sucks the desired air quantity into the tank and distributes it, uniformly and in very fine bubbles over a certain cross‐section. The design and operational characteristics of a mechanical defoamer are described. The defoamer is mounted to the top of the fermentation tank and separates foam by centrifugal force into air and liquid. It is capable of handling foams of different composition and quality without, the addition of anti foam agents. Using submerged vinegar fermentation, production of baker's yeast., and industrial waste, water treatment as examples, the performance of aerators and defoamers of different, sizes is discussed.
Biosynthesis of D‐mannitol from D‐glucose by Aspergillus candidus
Authors: Smiley K. L. , Cadmus M. C. , Liepins Patricia
Published: December 2004

Mannitol has long been known as a product of glucose metabolism by some strains of Aspergillus. Apparently no concerted effort, has been made to develop a practical fermentation process to make mannitol. Work at the Northern Laboratory has shown that nearly all strains of white Aspergillus produce significant amounts of mannitol; many strains of black Aspergillus also have this characteristic. Aspergillus candidus NRRL 305 is an exceptionally good mannitol producer. Studies on a fermentation process were conducted in 20‐1, stainless steel fermentors, without baffles. Czapek‐Dox medium, modified by addition of corn meal, yeast extract, and enzymatically hydrolyzed casein was the most satisfactory medium tested. Suitable increments of glucose were fed daily to the fermentors. The duration of the fermentation was from 10 to 16 days. The effects of agitation, aeration, temperature, and pH of the medium were studied. Under optimal conditions yields of mannitol approached 50% of the glucose consumed.
Kinetic behavior of heterogeneous populations in completely mixed reactors
Authors: Gaudy A. F. , Ramanathan M. , Rao B. S.
Published: December 2004

The kinetic behavior of heterogeneous microbial populations was studied in a continuous flow completely mixed reactor operated at various dilution rates. Glucose was used as the growth‐limiting nutrient. The physiological growth parameters for cells harvested from continuous flow reactors were determined using batch experiments. It, was found that the growth parameters, maximum growth rate (μm), saturation constant (ks), and cell yield (Y) vary for each dilution rate, and cannot be considered as precise constants in depicting the kinetic behavior of heterogeneous populations. In addition, it was found that the yield coefficients obtained from batch experiments were always lower than those obtained from continuous flow experiments. Levels of substrate and biological solids calculated for different dilution rates using growth constants from batch experiments did not agree with the experimental values observed in steady‐state experiments. However, when the yield values from, the continuous flow experiments were used in conjunction with batch values for μm and ks the theoretical and experimental dilute‐out curves agreed fairly closely (within the range needed for engineering prediction) until the culture began to wash out of the unit. In general, the data substantiated the use of the single phase relationship between growth rate and substrate concentration described by the Monod equation, μ = μmS/(ks + s).
A kinetic study of the alcoholic fermentation of grape juice
Authors: Holzberg I. , Finn R. K. , Steinkraus K. H.
Published: December 2004

The alcoholic fermentation of grape juice by a wine yeast was studied batchwise at pH 3.6 and 4.05 to develop kinetic equations relating cell concentration, N, to product concentration, P. In the exponential growth phase

where A, B, and C are constants, and μ is the specific growth rate. In the stationary phase, where the cell population is constant,

was found to apply. This equation, which incorporates a stoichiometric constant, Pm, predicted correctly the operation of a continuous fermentor at pH 3.6 and at 4.05. To study more fully the effect of alcohol concentration on yeast growth, a continuous fermentor was used in which the grape juice feed was supplemented with pure alcohol. At pH 3.6 the specific growth rate varied as,

There was no growth inhibition below an alcohol concentration of 2.6 g./100 cc., but inhibition was complete above 6.85 g./100 cc. This is a modified form of the relation suggested by Hinshelwood.1 The data suggest that growth in batch culture was limited not only by alcohol but also by some other factor, probably a nutritional deficiency.
The role of bacteria in copper mining operations
Authors: Beck Jay V.
Published: December 2004

The results of our survey of several mining operations have shown in every instance typical T. ferrooxidans bacteria to be present in the leaching solutions. The numbers of bacteria found are in general what, one would expect considering the chemical reactions occurring in these processes. A major difficulty is encountered when one considers the complex and unknown series of events which occur, as the bacteria‐bearing, acidic, ferric‐ion solution penetrates the massive ore dumps. Laboratory studies show microbial activity to be the major cause of rapid solubilization of copper sulfide ores. Field studies suggest that microbial activity cannot explain all observations in a typical leaching operation.
Dynamic measurement of the volumetric oxygen transfer coefficient in fermentation systems
Authors: Bandyopadhyay B. , Humphrey A. E. , Taguchi H.
Published: December 2004

A rapid and internally consistent technique has been developed to measure the volumetric oxygen transfer coefficient, kLa, in fermentation systems. The method consists of tracing the dissolved O2 concentration of the fermentation broth during a short interruption of the aeration. The O2 concentration trace thus obtained can be analyzed to determine the values of kLa. Additional experiments on prolonged O2 starvation, carried out to find the limitation of the technique, suggest that O2 uptake rate will vary if a prolonged (2–10 min.) O2 starvation occurs.
Long‐lived steam‐sterilizable membrane probes for dissolved oxygen measurement
Authors: Bokkowski John D. , Jhonson Marvin J.
Published: December 2004

Steam‐sterilizable membrane probes that are virtually maintenance‐free and capable of operation for over 1 year are described. The probes can withstand repeated steam sterilizations. They have a silver cathode, a lead anode, an acetate buffer, and a Teflon membrane. The probes have a linear response from below 0.00002 to over 0.2 atm. of oxygen.
Sterilization with gaseous ethylene oxide: A review of chemical and physical factors
Authors: Ernst Robert R. , Doyle John E.
Published: December 2004

Although the basic parameters for ethylene oxide sterilization are established, it is sometimes difficult to attain in practice where the principal limiting factor is moisture availability. There are situations which can limit or enhance the dynamics of sterilization. Such factors, if overlooked, could upset experiments and lead to erroneous conclusions, or defeat the sterilization process entirety. Such are, namely: stratification effects, diffusion barriers, moisture‐reducing effects, polymerization, and temperature distribution gradients.