bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial translational motions of base pairs in DNA molecules: Application of the extended matrix generator method
Authors: Marky Nancy L. , Olson Wilma K.
Published: May 2005

We have used the elementary generator matrices outlined in the preceding paper to examine the conformational plasticity of the nucleic acid double helix. Here we investigate kinked DNA structures made up of alternating B‐ and A‐type helices and intrinsically curved duplexes perturbed by the intercalation of ligands. We model the B‐to‐A transition by the lateral translation of adjacent base pairs, and the intercalation of ligands by the vertical displacement of neighboring residues. We report a complete set of average configuration‐dependent parameters, ranging from scalars (i.e., persistence lengths) to first‐ and second‐order tensor parameters (i.e., average second moments of inertia), as well as approximations of the associated spatial distributions of the DNA and their angular correlations. The average structures of short chains (of lengths less than 100 base pairs) with local kinks or intrinsically curved sequences are essentially rigid rods. At the smallest chain lengths (10 base pairs), the kinked and curved chains exhibit similar average properties, although they are structurally perturbed compared to the standard B‐DNA duplex. In contrast, at lengths of 200 base pairs, the curved and kinked chains are more compact on average and are located in a different space from the standard B‐ or A‐DNA helix. While A‐DNA is shorter and thicker than B‐DNA in x‐ray models, the long flexible A‐DNA helix is thinner and more extended on average than its B‐DNA counterpart because of more limited fluctuations in local structure. Curved polymers of 50 base pairs or longer also show significantly greater asymmetry than other DNAs (in terms of the distribution of base pairs with respect to the center of gravity of the chain). The intercalation of drugs in the curved DNA straightens and extends the smoothly deformed template. The dimensions of the average ellipsoidal boundaries defining the configurations of the intercalated polymers are roughly double those of the intrinsically curved chain. The altered proportions and orientations of these density functions reflect the changing shape and flexibility of the double helix. The calculations shed new light on the possible structural role of short A‐DNA fragments in long B‐type duplexes and also offer a model for understanding how GC‐specific intercalative ligands can straighten naturally curved DNA. The mechanism is not immediately obvious from current models of DNA curvature, which attribute the bending of the chain to a perturbed structure in repeating tracts of A · T base pairs. © 1994 John Wiley & Sons, Inc.
Some effects of microbial growths on surfactant properties of fuels
Authors: Krynitsky John A. , McLaren George W.
Published: May 2005

Fungi and bacteria taken from fuel systems were allowed to grow in jet fuel (or hydrocarbon)–salt solution mixtures and the layers were analyzed for surfactant properties. The fuels included both JP‐4 and JP‐5 types and an alkylate bottom fraction. Controlled surface activity was imparted to some samples by adding minute quantities of either petroleum sulfonates or petroleum naphthenates. Analyses after growth periods of 2 to 14 weeks failed to show any significant increases in the surface active properties of any fuel or hydrocarbon sample. In all cases, there was either little change or else the surfactant effect was reduced slightly. Opposed to these findings, examination of the aqueous bottoms revealed that microbial growths did effect increases in their surface active properties.
Fractionation of cell constituents of Bacillus megaterium in a polymer two‐phase system
Authors: v. Hofsten Bengt , Baird G. David
Published: May 2005

The distribution of various cell constituents of Bacillus megaterium has been studied in an aqueous two‐phase system containing the two polymers dextran and polythylene glycol. The difference in behaviour between cell walls, lipid granules and soluble cell material are such that a considerable fractionation of a suspension of disrupted cells may be obtained after a few counter‐current distributions. A mixture of whole cells and protoplasts can also be fractionated in this phase system. If sodium chloride is added to the phase system, vegetative cells and spores can be separated from each other.
Determination of oxygen and carbon dioxide using a paramagnetic oxygen analyzer
Authors: Phillips K. L.
Published: May 2005

A method by which a paramagnetic oxygen analyzer is used to determine oxygen consumption and carbon dioxide production during aerobic fermentation of Torulopsis utilis is described. The volume of carbon dioxide produced is not necessarily related to the volume of oxygen consumed by the microorganisms. For this reason, all carbon dioxide is removed from the effluent gas before it enters the analyzer when determining oxygen consumption. A method for calibrating the analyzer to correct for this removal is outlined. When determining carbon dioxide, effluent gas bypasses the carbon dioxide absorption tower before entering the analyzer. The carbon dioxide which it contains dilutes the oxygen remaining in the gas. The magnitude of this dilution can be used to calculate the percentage of carbon dioxide produced in terms of the air flow to the fermentor. Equipment required to alternately measure and record oxygen consumption and carbon dioxide production is described.
Polyglutamic acid production by Bacillus subtilis NRRL B‐2612 grown on wheat gluten
Authors: Ward R. M. , Anderson R. F. , Dean F. K.
Published: May 2005

Bacillus subtilis NRRL B‐2612, isolated at this laboratory, was used to produce polyglutamic acid from devitalized wheat gluten. Conditions for production of the polypeptide were investigated. When NRRL B‐2612 was grown on wheat gluten in shaken flasks with phsophate buffer and salts at pH 6.5, yields of polymer reflected a 25–40% incorporation of glutamic acid into polyglutamic acid. Repeated alcoholic precipitation yielded peptides containing between 45 and 90% D‐glutamic acid. Physical and chemical properties of a typical purified polyglutamic acid indicated that the product was a gamma‐linked polypeptide composed of 75% D‐glutamic acid and 25% L‐glutamic acid with a molecular weight of approximately 200,000.
Stability of product limited continuous culture systems
Authors: Mateles R. I. , Goldthwaite R. W.
Published: May 2005

An investigation was made of the stability of product limited continuous cultures of Saccharomyces carlsbergensis and Pseudomonas ovalis. No oscillations were found in pH or glucose concentration during the steady state, and no overshoot resulted from changing from one steady state to another.
A ventilated germ‐free cabinet for the microbiological laboratory
Authors: Harris‐Smith R. , Pirt S. J. , Firman J. E.
Published: May 2005

The design of a cabinet for the aseptic manipulation of material is described. The interior surfaces of the cabinet are sterilized by swabbing with a germicide. Germ‐free conditions are maintained during operation by means of a positive pressure of sterile air. A fan and filter unit attached to the cabinet is used to blow sterile air into the cabinet in sufficient quantity so as to flow out of the hand ports at a velocity of 50 ft./min. In the design, careful consideration was given to the ease of manipulations in the cabinet.
Biosynthesis of 7‐chloro‐6‐demethyltetracycline in the presence of certain homocysteine derivatives and methoxinine
Authors: Neidleman S. L. , Albu Evelyn , Bienstock Evelyn
Published: May 2005

Addition of the S‐2‐hydroxyethyl‐, S‐2‐chloroethyl‐, S‐n‐propyl‐, and S‐iso‐propyl‐derivatives of homocysteine, and methoxinine to S. aureofaciens (ATCC 13900) fermentations resulted in production of 7‐chloro‐6‐demethyltetracycline in addition to the normally synthesized 7‐chlortetracycline.
Beta‐carotene production in 20‐liter fermentors
Authors: Ciegler Alex , Lagoda Adolph A. , Sohns Virgil E. , Hall Harlow H. , Jackson Richard W.
Published: May 2005

Microbiological production of beta‐carotene previously investigated in shakenflask culture has been scaled‐up to 20‐liter fermentors containing an operating volume of 10‐liters. Yields obtained in shaken flasks, approximately 100 mg./100 ml. have been reproduced with a fermentation time of 72 hr. Factors affecting the fermentation: inoculum, mash ingredients, and environmental conditions, were investigated. Typical data are presented. A preliminary cost analysis indicates a “cost to make” of $31.35/kg. of carotene contained in the dried fermentation solids.
Plate assay methods for amino acids. 2. Factors affecting the cup plate assay for lysine with Streptococcus faecalis ATCC 6057
Authors: Bolinder Arne E. , Lie Sturla , Ericson L.‐E.
Published: May 2005

A number of factors was found to affect the cup plate assay for lysine with Streptococcus faecalis ATCC 6057. Hydroxylysine, aspartic acid, and Tween 80 were found to be among the essential components of the assay medium. Removal of any of these three components produced diffuse growth zones or otherwise unsatisfactory plates. The inclusion of asparagine and additional dipotassium phosphate to the medium was found to be advantageous but not an absolute requirement. It was important not to autoclave the hydroxylysine and the additional dipotassium phosphate together with the rest of the assay medium, but to add these components to the sterilized medium immediately before pouring the plates. With certain concentrations of hydroxylysine in the medium, the addition of L‐glutamine was found to potentiate the effect of hydroxylysine and thereby improve the lysine plates. The effect of graded amounts of the above mentioned medium components and of the pH of the assay medium was also studied. Increasing the sterilization time of the medium from 5 to 10 min. at 120°C. improved the readability of the lysine plates and led to more easily reproducible results. Factors influencing the preparation of the inoculum for the lysine plates were also studied: the age of the stab culture, the amount of inoculum used per plate, and the influence of the nature of the suspension medium used for washing the inoculum.
Effect of pressure waves on bacteria suspended in water
Authors: Lundbeck H. , Sköldberg O.
Published: May 2005

Shock pressure waves with a frequency of 50/sec. and a maximal pressure of 60–70 kg./cm.2 greatly reduced the viability of E. coli. A similar effect was obtained also on staphylococci, enterococci, Salmonella Zanzibar, and coliphages T2. On the contrary no effect on spores of B. subtilis was found. The effect was practically independent of the maximal pressure within the range from 30–80 kg./cm.2, the highest pressure tested. The effect decreased with increasing cell density of the bacterial suspension. Bacteria surviving shock treatment died considerably more rapidly when stored at 4°C. than bacteria treated in the same way except for exposure to pressure waves. Morphological examinations with the aid of ordinary light microscopy as well as electron microscopy suggest that the effect was due to mechanical action on the bacterial cell walls.
Criteria for biodegradable syndets
Authors: Barnhart Edwin L. , Eckenfelder W. Wesley
Published: May 2005

With the emphasis being given to the development of biologically soft detergents, it is necessary to establish eriteria defining biodegradability of these materials. It is the authors' opinion that a biologically soft detergent should have the following characteristics: (1) Under normal operations the material should be 85% removable by activated sludge. (2) Normally high discharges of the detergent should not influence biological activity. (3) The detergent should ultimately degrade to carbon dioxide and water.
Reproduction of distillers' yeasts
Authors: de Becze George I.
Published: May 2005

Distillers' yeasts, strains of Saccharomyces cerevisiae, although capable of sexual reproduction, in distillery practice reproduce asexually, by budding. A cell may bring forth another one in 50 min. With every ounce of whiskey produced, 30 billion new cells come to existence. Within a few days, in 4–8 propagation stages, a test tube full of culture will populate 100,000 gallons beer with 150 million cells per ml. Rate of reproduction, the number of new cells per each original cell varies from 5 to 50 in the various propagation stages. The number of new cells produced in a given nutrient is independent from the number of initial cells; and the utilization of the nutrient increases with the dilution of the substrate. Although distillers' yeasts may reproduce at such extremes as 1–46°C, 2½–10½ pH, presence of 0–15% alcohol by volume, and 0.1–25% sugar content, in distillery practice the factors are so selected to maintain conditions close to the optimum. When placed in the nutrient the initial cells will measure the chemical and physical characteristics of the new living space and the cell population, and will prepare a design of reproduction best suited to the conditions. The design includes a symmetry in the grouping of the cells and a rhythmic timing in starting new buds. Each healthy cells is biologically equal to the others and is capable of performing all functions characteristic of the strain. In spite of the sensitive coordination system between the individual cells that regulates their activity, marked differences exist among the cells to the degree of cell individuality. Distillers yeasts are superbly equipped to live and reproduce.
Aeration‐agitation studies on the rifamycin fermentation
Authors: Virgilio A. , Marcelli E. , Agrimino A.
Published: May 2005

Aeration and agitation conditions in 250 l. baffled fermenters with different impeller diameters, speeds, and air flows were studied during fermentations for the production of rifamycin, a new antibiotic produced by Streptomyces mediterranei. Dissolved oxygen concentration was continuously measured and the courses of power input, oxygen diffusion rate QO2, dry weight, viscosity, pH, sugar utilization, and antibiotic titer determined. Higher antibiotic yields occurred when the oxygen demand of the culture was satisfied and an excess of dissolved oxygen was still present during a critical period of the fermentation between the 50th and the 80th hr. To meet this requirement a power input of about 3.0 w./l. and an air flow ranging from 0.8 to 1.5 l./l./min. were found to be necessary.
Bacterial sulfide production from sulfate‐enriched spent distillery liquor. III.
Authors: Ghose T. K. , Mukherjee S. K. , Basu S. K.
Published: May 2005

Semicontinuous sulfide fermentation has been conducted with distillery spent liquor as the source of carbon employing a strain similar to Desulphovibrio rubentschikii. Mineral barites and gypsum have been used as the hydrogen acceptors during the studies. Results reveal that mineral barites can also react very favorably as hydrogen acceptors. Sulfates have been used both in powdered (200 mesh) and lumpy (1/4‐1/2 in. size) forms. When applied in lumpy form in a packed tower, both the mineral sulfates produced higher yields of sulfide compared to their corresponding finely pulverized states. Thus, under similar conditions, fermentation conducted with pulverized gypsum showed a yield of 450–550 p.p.m. hydrogen sulfide, whereas the yield was as high as 750–1025 p.p.m. when gypsum lumps were used as a packing. Corresponding figures with barites are 300 and 540 p.p.m., respectively. Continuous sulfide fermentation has also been conducted in a packed tower containing lumpy gypsum as the packing under total recirculation. Daily buildup of sulfide was observed to be as high as 180 mg./l. of fermenting medium. Appreciable reduction in COD of the effluent was observed during the above studies. Thus, with barites, per cent COD reduction values were 30–35, 45–50, 60–65, and 75–80 with retention periods of 10, 15, 25, and 35 days, respectively. With gypsum, per cent COD reduction was 50–70 with 10 days's residence time. The effects of the retention period on sulfide yield and volatile acid content were also studied. The longer the retention period, the higher is the sulfide yield and the lower the volatile acid content of the discharge becomes. Studies were also conducted to find the correct composition of volatile acids in the discharge, as well as the levels of their concentration during continuous feeding and discharge over a number of days. It has been observed that during 18 hr. of fermentation in a batch, volatile acid concentration increased from 6.76 m. to 15.01 mmoles per liter of medium of which 10 mmoles are acetic, 0.833 mmoles butyric, and 4.16 mmoles propionic acid. Studies on soluble and insoluble sulfate balance have also been made in a synthetic medium containing calcium acetate as the substrate. Unaccounted for sulfates were negligible and a deviation between the actual and calculated sulfide yield did not exceed 2%. It is also observed that, when fermentations are conducted in sulfate packed columns, the color of the effluent becomes paleyellow containing very little suspended and volatile matter compared to the deep‐black color of the emuent emerging from a ferrnenter fed with pulverized sulfates. This liquor contains 0.5271% soluble ash (computed as potash) and might be a good source of potash.
Growth of a yeast of normal alkanes
Authors: Miller Thomas L. , Lie Sturla , Johnson Marvin J.
Published: May 2005

A soil isolate, HD‐5, identified as closely resembling Candida intermedia, was grown on normal alkanes ranging from dodecane (C12) to octadecane (C18). The growth rate of the organism increased with increasing length of the alkane chain. The shortest generation time was 4.5 hr. with octadecane as the carbon source. Cell yields of 82% were common with even numbered alkanes from C14 through C18. The cell yields appeared to decrease with shorter chain (C12 or below) and odd‐numbered chain alkanes. The cellular nitrogen ranged from 6.9 to 7.5% and the highest lipid content found was 10.3% (with C17).
Studies on the purification of vaccinia virus
Authors: Orlando M. D. , Riley J. M. , Patrick W. C.
Published: May 2005

Various methods for the removal of extraneous matter from vaccinia virus suspensions are described and compared. Of ten procedures tested, differential centrifugation and Freon extraction were the most successful. Both the partially purified suspensions and the dried products prepared from them had high virus titers in embryonated eggs and high infectivity for mice. Although both processes resulted in products with the same titers, the differentially centrifuged product was approximately tenfold more purified as shown by the percentage solids of the suspensions before freeze drying.
Oxygen transfer mechanisms in the gluconic acid fermentation by Pseudomonas ovalis
Authors: Bennett Gary F. , Kempe Lloyd L.
Published: May 2005

The oxygen uptake rate to suspended cells of Pseudomonas ovalis was measured in two ways using the same cell suspension. Initially the rate was found by measuring the rate of production of gluconic acid by cells suspended in a nitrogenfree, aerated medium. Then, an oxygen electrode was used to measure the rate of transfer of dissolved oxygen to cells suspended in a liquid that was being agitated but not sparged. These rates were markedly different. It was found that agitation affected the oxygen transfer rates in aerated solutions at dissolved oxygen concentrations well above the critical level, but had no affect on the oxygen uptake rates by cells suspended in an unsparged but agitated medium. The data suggested that an additional path existed for oxygen transfer. This alternate route, parallel to the conventional pathway of oxygen transfer, becomes operative when the liquid films surrounding the cells and bubbles merge. The resulting shorter path presents a mechanism for direct transfer of oxygen which increases in importance as the gas−liquid interfacial area increases.
Flexibility in cultivation equipment. I. A small‐scale continuous culture apparatus for the study of complex processes
Authors: Holmström Björn , Hedén C.‐G.
Published: May 2005

A cultivation apparatus made up from six small (80−800 ml.) glass units with independent pH‐, aeration‐, and foam control is described. Exchangeable attachments made it possible to run the unit both batchwise and continuous and to connect up the units in various fashions.
Die kontinuierliche Züchtung von Mikroorganismen als apparatives problem
Authors: Fiechter A.
Published: May 2005

Bei der kontinuierlichen Züchtung von Mikroorganismen ist die zuverlässige Aufrechterhaltung des stationären Zustandes die Grundbedingung für die erfolgreiche Untersuchung der biologischen Probleme. Auftretende Instabilitäten können apparativen oder biologischen Ursprunges sein; eine einwanddfrei funktionierende Ausrüstung ist daher bei der Einführung der Kontinuität primäres Erfordernis. Es wird auf die wichtigsten Ursachen, welche zu Instabilitäten führen können, eingegangen und eine Laborapparatur beschrieben, welche eine Basisausrüstung umfasst, die speziell für hohe Betriebssicherheit und Einfachheit der Bedienung ausgelegt wurde. Besondere Aufmerksamkeit wurde der Konstanz des Zuflusses f des Mediums, und des arbeitenden Volumens v, sowie der sicheren Ausschaltung von Infektionen durch Verwendung sterilisierbarer pH‐Elektroden und eines Membranverschlusses geschenkt.
Sterilization of microbiological media with β‐propiolactone
Authors: Holme Tord
Published: May 2005

A procedure for sterilization of microbiological media with β‐propiolactone has been developed. Special attention was paid to the maintenance of mild conditions to enable the treatment of media sensitive to high temperature or low pH. The maximum temperature allowed was 40°C. and automatic neutralization of acid produced during hydrolysis was effected by the use of titration unit. The apparatus could be used for several successive sterilization cycles without disconnection.
Production of industrial‐grade polysaccharide B‐1459
Authors: Rogovin P. , Albrecht W. , Sohns V.
Published: May 2005

A method to make purified polysaccharide synthesized exocellularly from cereal carbohydrates by the bacterium Xanthomonas campestris NRRL B‐1459 and a characterization of its properties have been reported previously by this Laboratory. Because of increasing commercial interest in a less purified polymer, we have extended our work to include production of a lower cost industrial‐grade product. Fermentation of media containing 2.25% corn sugar, seeded with 5% inoculum of X. campestris NRRL B‐1459 and cultured aerobically at 82°F., is complete in 96 hr. The viscous fermented broth contains about 1.5% polymer. A tan product containing approximately 60% polymer and having good viscosity characteristics is obtained by drum drying the fermented broth at steam pressures below 40 p.s.i.g, 287°F. Drying at higher temperatures adversely affects viscosity. A good product is also obtained by spray drying. Cost estimates indicate that 5 million lb./yr. of dried crude solids could be produced for 37 cents/lb. by drum drying or for 41 cents a pound by spray drying.
Changes in acid soluble nucleotide components of candida utilis during the cell cycle
Authors: Hampton A. N. , Dawson P. S. S.
Published: May 2005

Acid soluble extracts obtained at 30 min intervals from cells of C. utilis growing in synchrony in a phased culture (cycle time 51/2 hr) were fractionated on a Dowex‐1‐formate column. The series of fractionation profiles showed changes in number and amounts of components over the cell cycle. Transient accumulations of numerous components over the complex pool were observed. The significance of the changes are discussed in relation to practical applications and cell metabolism.
Adriamycin, 14‐hydroxydaimomycin, a new antitumor antibiotic from S. Peucetius var. caesius
Authors: Arcamone F. , Cassinelli G. , Fantini G. , Grein A. , Orezzi P. , Pol C. , Spalla C.
Published: May 2005

Streptomyces peucetius var. caesius, obtained from S. peucetius, the daunomycin producing microorganism, by mutagenic treatment, differs from the parent culture by the color of the vegetative and aerial mycelia and by its antibiotic, producing ability. S. peucetius var. caesius accumulates adriamycin in submerged and aerated culture on a medium containing glucose, brewer's yeast, and inorganic, salts both in shake flasks and in stirred fementers. Isolation of the product is performed by solvent extraction, chromatography on buffered cellulose columns, and crystallization as the hydrochloride. The new antitumor agent, adriamycin, is the 14‐hydroxv derivative of daunomyein.
Biosynthesis of chloramphenicol
Authors: Westlake D. W. S. , Vining L. C.
Published: May 2005

The current knowledge concerning the biosynthesis of chloramphenicol is discussed. Cultures of Streptomyces sp. 3022a fed 14C‐shikimie acid incorporated the label to the same extent into phenylalanine, tyrosine, and chloramphenicol. Of possible precursors of the phenylpropanoid nucleus of this antibiotic only p‐aminophenylalanine and DL‐threo‐p‐amino phenylserine specifically labeled chloramphenicol. On the basis of these results a pathway for the biosynthesis of chloramphenicol is presented. The lack of specific incorporation of 15N‐nitrogen from a competitive feeding experiment in which both l5N‐nitrate and 14N‐DL‐serine were fed to growing cultures suggests that both the amido‐ and the nitro‐nitrogen atom present in this antibiotic are derived from a common pool. Studies on the enzyme, DAHP synthetase, show that in streptomyces sp. 3022a it is not subject to feed back inhibition by either phenylalanine, tyrosine, or chloramphenicol.
Activation of the biosynthesis of carotenoids by Blakeslea trispora
Authors: Ninet L. , Renaut J. , Tissier R.
Published: May 2005

The research carried out by several scientists has made possible the industrial preparation of β‐carotene by fermentation. A fungus, Blakeslea trispora, abundantly synthesizes carotenoids when its two opposite forms are cultivated together in a special fatty medium. When ionones or other natural substances are introduced into the culture, a very obvious increase in the biosynthesis of carotenoids, more specifically of β‐carotene, is obtained.

Our own work has shown that; (1) several synthetic products chemically related to β‐ionone, such as 2,6,6‐trimethyl‐l‐acetyleyelohexene, can advantageously replace either partially or totally the ionones as inductors of the biosysnthesis of β‐carotene; (2) various nitrogen‐containing substances when added to the culture medium can considerably enhance the biosysnthesis of carotenoids while sometimes very specically orienting it. Their action comes on top of that of the ionones or their substitutes; actually this action is unexplained.

Thus certain amides, imides, lactams, hydrazides, or substituted pyradines, and in particular succinimide and isonicotinoylhydrazine, have produced a two or threefold increase in the quantity of β‐carotene present in the culture media of Blackeslea trispora.

Conversely some heterocyclic substances such as pyridine itself or imidazole totally inhibit the biosysnthesis of β‐carotene but induce the production of very important quantities of lycopene.
Transformation of steroids by mixed cultures
Authors: Ryu D. Y. , Lee B. K. , Thoma R. W. , Brown W. E.
Published: May 2005

Some results of our studios on transformation of steroids by mixed culture fermentation are presented in this paper. Arthrobacter simplex was paired in turn with each of the following: Streptomyces roseochromogenes, Curvularia lunata, Absidia coerulea, and Aspergillus ochraceus. The steroid substrates examined for multiple transformation were 16α‐hydroxy‐cortexolone, 16α‐hydroxy‐cortexolone 16,17‐acetonide, 9α‐fluorohydrocortisone, 9α‐fluorohydrocortisone 21‐acetate, and 9α‐fluorohydrocortisone 21‐hemisuccinate. The effects of media, steroid substrate, and microbial interaction in a mixed culture on the induction and repression of steroid transforming enzymes were unique to each case studied. The reaction mechanism of the multiple steroid transformation was also found to vary from one mixed culture system to another. Two different reaction mechanisms were observed, namely, consecutive and parallel. In the former, one of the two enzymatic reactions always preceded the other, while in the latter, two different enzyme reactions occurred simultaneously, thereby giving rise to two different intermediates. Multiple transformation of steroids by a single step mixed culture fermentation has potential economic advantages.
Oxygen absorption in microbiological systems of zero order reaction rate
Authors: Tsao George T.
Published: May 2005

A model of oxygen absorption in microbiological systems of zero order reaction rate is proposed. The partial differential equation was solved to predict the profile of the oxygen concentration boundary layer next to a gas‐liquid interface. Generally speaking, the presence of microbial cells always helps to increase the oxygen absorption rate over that of physical absorption. Only when the microbiological reaction is slow as judged by the fact that the reaction time, tr, is much larger than the diffusion time, tD, can one rightfully approximate the oxygen absorption in microbiological suspensions by physical absorption.
Continuous fermentation to produce xanthan biopolymer: Laboratory investigation
Authors: Silman R. W. , Rogovin P.
Published: May 2005

Xanthan biopolymer has been produced by single‐stage continuous fermentation with Xanthomonas campestris NRRL B‐1459 in a medium of glucose, minerals, distillers' solubles, and urea for as long as 20 days. At the highest dilution rate studied (D = 0.0285 hr−1), the steady state rate of xanthan production was 0.36 g/kg/hr and the steady state yield, basis glucose consumed, was 68%. Observations indicate that xanthan production rate is a function of pH and D.
A wet spinning apparatus and auxiliary equipment suitable for preparing samples of oriented DNA
Authors: Rupprecht A.
Published: May 2005

Samples of oriented DNA prepared by wet spinning have been found to be very useful for physicochemical and biochemical studies with various techniques. The results obtained yield information on such fundamental properties of DNA as its hydration, electrical conductivity, and its interaction with irradiation and mutagenic and carcinogenic substances. Against this background a detailed description is given of the wet, spinning apparatus and of the techniques developed to produce bigger samples from spun films of oriented DNA. Photographic illustrations are used to give a clear picture of the various details. Extensions of the wet spinning method are discussed.
Engineering factors in single‐cell protein production. I. Fluid properties and concentration of yeast by evaporation
Authors: Labuza Theodore P. , Santos Daniel Barrera , Roop Robert N.
Published: May 2005

The processing of fermentor‐grown, edible yeast involves the removal of water. This can be accomplished through concentration followed by drum or spray drying. This study presents the essential physical properties of yeast solutions necessary for calculation of production economics. In addition, our initial studies of vacuum concentration show that some of the cell leakage necessary for good drying characteristics occurs. The residence time during concentration is also sufficient, to yield 1‐2 log cycles of kill which are mandatory since the final product, should contain no viable cells.
An enzyme kinetic model for describing fermentation processes
Authors: Tanner Robert D.
Published: May 2005

An enzyme kinetic model has been proposed to describe fermentation processes. This type of model was chosen because it is biologically sound, can incorporate all of the important engineering control variables, and can draw upon, in its development, the extensive kinetic literature. An intial qualitative test for this model was made on the gluconic acid fermentation. A necessary check of the model was that Monod's empirical cell growth and yield equations were derived as a special case. The model also offered an explanation for the hysteresis behavior of the gluconic acid production rate as a function of gluconolactone.
Microbial cell recovery enhancement through flocculation
Authors: Gasner Larry L. , Wang Daniel I. C.
Published: May 2005

The removal of cellular material from fermentation broths is of importance in many fermentation processes. The present work compares the performance of recently developed polyelectrolyte flocculating additives with traditionally available additives. Objectives are to establish criteria for the choice of a flocculating additive and establish optimum conditions for the formation of stable, fast settling floe, and for quantitative separation of cellular material from the medium. Fermentation broths of actively growing Candida intermedia were used to evaluate the effectiveness of fifty commercial flocculating additives at different dosages and pH values. Certain strong anionic and strong cationic polyelectrolytes and mineral hydrocolloids were found to be most effective in their enhancement of settling rates. Some differences in behavior exist between glucose grown cells, hydrocarbon grown cells, and washed cells in buffer suspension. Flocculation of cells from fermentation broths is concluded to be highly dependent upon adsorbed material. A high charge density to interact or compete with adsorbed material and a solubility in the adsorbed material are important factors in choosing an additive for a given application. The fluid mechanics of a flocculating suspension is an important variable since low shear does not provide adequate contacting between cells for floe formation and high shear leads to floe breakup. An apparatus was constructed to grow floe under constant fluid mechanical conditions both in laminar and turbulent flow regimes. Turbulent shear was found to be very important in forming large, compact floe in cases where irreversible ionic bridging is the mechanism as for the strong anionic polyelectrolyte, polystyrene sulfonate. Adequate mixing is required to disperse the flocculating additive, but the level of turbulence is relatively unimportant in cases where reversible colloidal bridging is the mechanism as for the mineral hydrocolloid, bentonite.
Gram‐Scale purification of arginine, formylmethionione, glutamic acid and phenylalanine transfer ribonucleic acids from E. coli K‐12 MO7
Authors: Weeren H. O. , Ryon A. D. , Heatherly D. E. , Kelmers A. D.
Published: May 2005

Gram‐sized quantities of purified arginine, formylmethionine, glutamic acid, and phenylalanine‐2 tRNAs have been prepared from pools of E. coli K–12 MO7 mixed tRNAs by reversed‐phase chromatography after preliminary fractionation on DEAE‐cellulose. Purified formylmethionine tRNA and partially purified arginine tRNA and glutamie acid tRNA were obtained from large‐scale RPC–3 runs (4 × 36 in. column). The arginine tRNA was further purified by rechromatography on RPC–4 columns, and the gluatmic acid tRNA by rechromatography on an RPC–3 column. Two phenylalanine tRNAs were resolved on large‐scale (2 × 96 in. column) RPC–3 runs; only the second phenylalanine tRNA reached a satisfactory degree of activity. About 0.88 g of arginine tRNA, 70% activity; 3.32 g of formylmethionine tRNA, 97% activity; 0.80 g of glutamic acid tRNA, 83% activity and O.92 g of phenylalanine‐2 tRNA, 78% activity, were produced. The processing steps employed are reliable and reproducible and the procedure is amenable to routine production of these tRNAs.
Microbial production of D‐mannitol and D‐fructose from glycerol
Authors: Onishi Hiroshi , Suzuki Toshiyuki
Published: May 2005

In view of the recent development that some petrochemical products are efficiently available as substrates for the fermentation industry, glycerol manufactured from propylene by chemical synthesis would also be hoped for the purpose. This paper describes some of the factors influencing mannitol production from glycerol by Torulopsis yeasts and a microbial conversion of glycerol to D‐fructose via mannitol, in which two sequential steps of yeast and Acetobacter fermentation are involved. Torulopsis mannitofaciens CBS 5981 and Torulopsis vcrsatilis CBS 1752, exceptionally good mannitol producers, were selected for the study. High concentrations of nitrogen sources and KH2PO4 in the medium markedly decreased mannitol yield in spite of good utilization of the substrate. T. mannitofaciens produced mannitol in yield of 31% of the glycerol consumed at optimal condition. The fermentation by washed yeast cells gave much higher mannitol yield of more than 50%. A sequential fermentation process was carried out without isolation and purification of the intermediate and yielded.51.7%. D‐fructose from the glycerol.
A model for continuous enzymatic saccharification of cellulose with simultaneous removal of glucose syrup
Authors: Ghose Tarun K. , Kostick John A.
Published: May 2005

Cellulase of Trichoderma viride was concentrated in various molecular cutoff membranes, and flux rates and retention of activity were studied under ultra‐filtration conditions. Little or no Cellulase was discharged through the membranes tested. The concentrated (5–8‐fold) enzymes were used to saccharify finely ground substrate (Solka Floe) in stirred tank (STR) and membrane reactors (MR). A pressure filtration vessel provided with a membrane for simultaneous removal of low molecular weight products (glucose) from the reacting system (Cellulose‐Cellulase) is designated as a membrane reactor. Continuous digestion of dense cellulose suspension in the membrane reactor was achieved. Using PM‐30 (Amicon) membrane reasonably high mass flux values (9.7–23.3 gals/ft2—day) were obtained in separating glucose from a digest of 30% cellulose suspension. Abcor membrane (HFA 300) was equally effective and necessitated less care in handling. Nearly 14% glucose concentration has been achieved in less than 50 hrs in STR by digesting a 30% cellulose suspension. Based on experimental data a model system is proposed for the continuous steady state Saccharification of ground substrate in which there is continuous removal of concentrated glucose syrup, and a feedback of enzyme.
A method for obtaining protein concentrates from microorganisms
Authors: Hedenskog Gudmund , Mogren HÅRkan , Enebo Lennart
Published: May 2005

In order to isolate proteins from microalgae, yeasts and bacteria, cell disintegration in a special ball‐mill was performed. The degree of disintegration of the different microorganisms was compared. The dependence of disintegration on bead size and on the ratio between the volume of suspension and the volume of glass beads was also investigated. Nondisintegrated and disintegrated cells were extracted with sodium hydroxide and the amount of extractable nitrogen and the amount of nitrogen precipitable at pH 4.0 were determined. The dependence of yield on the sodium hydroxide concentration, extraction time, and temperature was studied. When extracting undisintegrated cells, very low yields were obtained and the nitrogen extracted was mostly nonproteinous. For disintegrated cells high yields were obtained. An optimum was found after extraction with 0.3–0.5% sodium hydroxide; at pH 11.0–11.5. The precipitate obtained represented 60–70% of the cell nitrogen. The nitrogen content of the precipitate was 12–14% of the dry weight.
Extended culture: The growth of Candida utilis at controlled acetate concentrations
Authors: Edwards V. H. , Gottschalk M. J. , Noojin A. Y. , Tuthill L. B. , Tannahill A. L.
Published: May 2005

Extended culture, a special type of semicontinuous culture, permits prolonged maintenance of a constant or programmed environment in a growing culture by a controlled addition of one or more substrates. Differences between extended culture and continuous culture data are a measure of differences in the properties of cell populations with different cell age distributions but identical steady‐state environments. Both extended culture and continuous culture were used to study the growth kinetics of Candida utilis (ATCC 9226) under conditions of substrate inhibition at controlled concentrations of sodium acetate in a carbon‐limited mineral salts medium supplemented with 0.01 g/1 yeast extract. Acetate concentrations ranged from 1.2 g/l to 10.8 g/l (expressed as acetic acid), while yeast concentrations varied from 0.3 to 7.8 (g dry cells)/1. Rate parameters such as growth yields (Y), specific growth rates (μ), and linear growth rates (K), were calculated by computer from the data and theory presented herein. Specific growth rates as high as 0.54/hr were observed, although extended culture growth was more nearly linear than exponential in these experiments. Growth yields usually varied between 0.2 and 0.4 (g dry cells)/(g acetate), although values were as high as 0.8 for a brief period during one experiment. Growth yields at a given acetate concentration were correlated by an equation of the form 1/Y = 1/YG + m/μ. A maintenance coefficient (m) of 0.17 (g acetate)/(g dry cell‐hr) was observed at acetate concentrations of 4.5 and 10. g/1. A typical maximum growth yield (YG) of 0.51 (g dry cell)/(g acetate) was obtained at 4.5 g/1 acetate, but an unusually high YG of 1.33 was found at 10. g/1 acetate. Oxygen uptake measurements are compared with these cell yield measurements. Linear growth rates in expended culture were correlated by the equation K = 0.89–0.70 (S/S0) where K has units of (g dry cell)/(l‐hr), S is the instantaneous acetate concentration, and S0 is the initial acetate concentration. The extended culture kinetic data are shown to be substantially different from continuous culture kinetic data. Reason for these differences are discussed in light of diffrences in the cell age distributions, as well as possible differences in experimental conditions.
Effect of mixing on the washout and steady‐state performance of continuous cultures
Authors: Fan L. T. , Erickson L. E. , Shah P. S. , Tsai B. I.
Published: May 2005

The effects of mixing on the critical mean holding time for washout and the steady state performance of growth processes in continuous flow reactors are investigated. Macromixing, micromixing, and cell recycle arc considered. The tanks‐in‐series model composed of N completely mixed flow reactors, the dispersion model, the plug flow model, and a combined model composed of a plug flow reactor and a continuous stirred tank flow reactor connected in series arc used to represent the macro‐mixing or residence time distribution. The extreme cases of micromixing, namely, complete segregation and maximum mixedness, as well as intermediate states of micromixing are investigated to determine their effects on washout and the occurence of multiple steady states. A technique for predicting the maximum mixedness washout condition from a knowledge of the residence time distribution is presented and used to determine the washout condition for the dispersion model under maximum mixedness conditions.
Model for continuous culture which considers the viability concept
Authors: Sinclair C. G. , Topivvala H. H.
Published: May 2005

The effect of the rate of ‘natural death’ of bacteria on the steady state behaviour of continuous culture has been studied. A model which has no real biochemical basis but which gives good experimental correlation has been proposed. Populations of Acrobacter Acrogenes harvested from the chemostat at dilution rates greater than 0.1 HR−1 were found to be over 95% viable. The effect of the rate of death on the steady state yields becomes significant only at very low dilution rates. The experimental work of other workers has also been simulated to test the validity of the model. Theoretically it is also shown that an ‘apparent’ lag in batch cultures will be observed if the innoculum is of very low viability.
The effects of glucose and oxygen on the cytochromes and metabolic activity of yeast batch cultures. I. Saccharomyces spp.
Authors: Rickard Pamela A. D. , Moss F. J. , Ganez Micheline
Published: May 2005

Saccharomyces cerevisiae and Saccharomyces carlsbergensis were grown in batch culture with and without oxygen control.

The concentrations of A‐, B‐ and C‐type cytochromes of both yeasts were dependent on the oxygen concentration during growth as well as on the initial glucose concentration of the growth medium. S. cerevisiae cytochromes were maximal after growth in low glucose and low oxygen; S. carlsbergensis cytochromes were maximal after growth in low glucose and high oxygen. Except when glucose was in very low concentration, its catabolism by S. carlsbergensis was directed predominantly towards ethanolic fermentation regardless of the oxygen concentration. Growth rate, total cell mass and yield were maximal, and anabolism was closely balanced with catabolism, when glucose and oxygen of S. carlsbergensis cultures were both high. Under these conditions neither catabolism, respiratory or ethanolic, nor glucose uptake were maximal.
Equipment for the automatic aseptic inoculation and sampling of microbial cultures
Authors: Lelieveld H. L. M.
Published: May 2005

Equipment has been designed and constructed for the automatic aseptic inoculation and sampling of microbial cultures. It enables fermentations to be started and samples to be taken round‐the‐clock, according to a predetermined program.

The equipment is suitable for microbial processes on both a laboratory and a factory scale.
The effects of glucose and oxygen on the cytochromes and metabolic activity of yeast batch cultures. II. Candida utilis
Authors: Rickard Pamela A. D. , Moss F. J. , Phillips D. , Mok T. C. K.
Published: May 2005

Candida utilis was grown in batch culture with and without oxygen control. The concentrations of A‐, B‐, and C‐type cytochromes were found to vary with the initial glucose concentration, with the dissolved oxygen concentration, and with time. A‐type was the most sensitive. After glucose was essentially exhausted, the yeast catabolized ethanol, if it had been growing in a relatively low initial glucose concentration, or non‐glucose carbohydrate, including some of that previously accumulated within the cell, if it had been growing in a high initial glucose concentration. This difference in metabolic pattern could explain why cytochrome derepression was initiated soon after glucose uptake ceased only if initial glucose had been relatively low. The effects of glucose and dissolved oxygen concentrations on yeast cytochromes and respiratory activity are discussed.
A mechanistic study of oxygen transfer in aqueous systems
Authors: Muchmore C. B. , Chen J. W. , BeMiller J. N.
Published: May 2005

Oxygen transfer coefficients were evaluated for a 14‐liter stirred tank fermentor equipped with an oxygen probe, employing elemental copper adsorbed on a weakly basic anion‐exchange resin as a solid phase oxygen acceptor. The use of a solid phase oxygen acceptor allowed evaluation of mass transfer resistances associated with the solid phase, and the effect of an oxygen adsorbing solid phase on the overall oxygen transport system, portions of the oxygen transfer process that are neglected by the conventional sulfite oxidation method commonly employed. It was concluded from the data obtained that a transport pathway involving transfer of oxygen to particles present near the air‐water interface was a significant oxygen transport pathway for the system studied. Oxygen probe measurements performed on the bulk liquid did not recognize this pathway, suggesting that data taken on biological systems by use of techniques involving oxygen concentration measurements in the bulk liquid may not give the true oxygen absorbing capacity of a system.