bluuebunny/crossref_metadata_2025 huggingface dataset:
CO2 Transport and photosynthetic productivity of a continuous culture of algae
Authors: Märkl H.
Published: December 2004

The photosynthetic activity of a continuous culture of the microalga Chlorella vulgaris as it is influenced by the CO2 concentration in the aerating air at different light levels is discussed. It is shown that the characteristic of this behavior is mainly determined by the CO2 transport from the air to the algal cell. Therefore the critical CO2 concentration necessary for optimal growth of a particular alga cannot be given in general, as it differs over a very wide range depending on the dispersion system used in the culture vessel. By analyzing experimental data by means of a mathematical model the overall transport coefficient in a well stirred system for the CO2 transport from the air bubble to the algal cell and the “actual” CO2 kinetics, can be calculated within reasonable limits of accuracy.
Poly(methoxygalacturonide) lyase immobilized via titanium onto solid supports
Authors: Hanisch W. H. , Rickard Pamela A. D. , Nyo S.
Published: December 2004

Poly(methoxygalacturonide) lyase (PMGL) (E.C. 4.2.2.10) was purified from a commercial preparation and immobilized by the metal link method. The properties of DEAE‐cellulose‐Ti‐PMGL and of porous glass‐Ti‐PMGL were compared with those of the native enzyme; despite the presence of the metal and the heterogeneity of the substrate, pectin, typical substrate–enzyme‐support interactions were demonstrated by shifts in pH optima and KM values. The possible industrial application of DEAE‐cellulose‐Ti‐PMGL is discussed.
Process for the aerobic conversion of poultry manure into high‐protein feedstuff
Authors: Shuler M. L. , Roberts E. D. , Mitchell D. W. , Kargi F. , Austic R. E. , Henry A. , Vashon R. , Seeley H. W.
Published: December 2004

A two‐stage aerobic continuous process is suggested for the conversion of poultry waste into a single‐cell protein (SCP) product. The technical feasibility of the process is examined in this paper. Using bench‐scale apparatus the approximate growth kinetics have been discovered. Possible modes of product recovery have been examined. The product consists primarily of a strain of Pseudomonas fluorescens which has a lysine‐rich (∼9.3%) amino acid profile that could make this product an attractive feed ingredient for poultry diets.
Steroid bioconversion in water‐insoluble organic solvents: Δ1‐Dehydrogenation by free microbial cells and by cells entrapped in hydrophilic or lipophilic gels
Authors: Yamané Tsuneo , Nakatani Hideki , Sada Eizo , Omata Tetsuo , Tanaka Atsuo , Fukui Saburo
Published: December 2004

A cell suspension in a water‐insoluble organic solvent (benzene: n‐heptane, 1 : 1 by volume) of Nocardia rhodocrous (previously induced to synthesize steroid Δ1dehydrogenase) rapidly catalyzed the stoichiometric oxidation of 4‐androstene‐3,17‐dione (4‐AD) to androst‐l,4‐diene‐3,17‐dione (ADD) in the presence of phenazine methosulfate (PMS). High levels of 4‐AD or PMS reduced the conversion rates. No appreciable decrease in the conversion rate was observed on adding aqueous buffer solution to the thawed ceils (up to 9.4 g water/g dry cell). The whole cells were immobilized by entrapment in a hydrophilic gel (H‐gel) or a lipophilic gel (L‐gel) by use of a water‐soluble or water‐insoluble photocrosslinkable prepolymer. The reticula of H‐ and L‐gel matrices were impregnated with water and organic solvent, respectively. Both the H‐ and L‐gels could convert 4‐AD to ADD in the presence of PMS, the L‐gel showing a slightly higher conversion rate. Various lines of evidence indicate that the limiting factor is the penetration rate of 4‐AD into gel particles for the H‐gel, and the penetration rate of PMS for the L‐gel. The catalytic activities decreased considerably after several successive runs with the free cell suspension system, while the immobilized cells were more stable, the stability of H‐gel and L‐gel being almost the same.
The role of interphase nitrogen transport in the dynamic measurement of the overall volumetric mass transfer cefficient in air‐sparged systems
Authors: Linek V. , Beneš P. , Hovorka F.
Published: December 2004

It has been shown both theoretically and experimentally that interphase nitrogen transport may have a significant influence on the rate of interphase oxygen transport, and thereby also on the value of the volumetric mass transfer coefficient of oxygen, kla, determined in mechanically agitated bubble fermentors using the variants of dynamic method presented in the literature. The experiments were carried out in 1M KCI solution at five stirrer frequencies and two gas inlet levels. The gas interchanges were performed either without interrupting the aeration and agitation of the charge (A) or with the aeration and agitation of the charge turned on at the same time (B). The applied variants of the interchange were N2→ O2→, O2→ N2, N2→ air, air→ N2, O→ O2, and O→ air. In the two last variants the oxygen dissolved in the charge was removed by reacting with sulfite ions. The kla values calculated by allowing for the nitrogen transport for procedure A were approximately equal to the values obtained by disregarding the nitrogen transport, whereas those for procedure B were higher (up to 40%), than the values obtained disregarding the nitrogen transport.
Use of immobilized cells of Rhizopus nigricans for the 11α‐hydroxylation of progesterone
Authors: Maddox I. S. , Dunnill P. , Lilly M. D.
Published: December 2004

The filamentous fungus, Rhizopus nigricans, was immobilized in polyacrylamide, alginate, and agar gels and its ability to 11α‐hydroxylate progesterone was examined. No activity was detected using polyacrylamide gel but both agar and alginate gels have proved capable of hydroxylation. Agar gels displayed faster rates and higher yields. It was possible to induce hydroxylase synthesis within agar and alginate gels, and microscopical examination provided evidence for hyphal growth within these gels. The concept of increased biomass was used to explain the observed increase in the rates of hydroxylase activity of the immobilized cells. Conversely, hyphal overcrowding was postulated for the rapid inactivation observed under some operating conditions.
The dynamics of commensalism
Authors: Stephanopoulos Gregory
Published: December 2004

The outcome of the interaction of two commensal populations growing in a continuous bioreactor depends on the operating conditions (dilution rate and feed concentration) and the shape and mutual disposition of the specific growth rate curves of the two populations. The stability of the possible steady states is analyzed by a new method based on the Poincaré index and a comprehensive portrait of the dynamics of the interaction of commensalism is presented. Potential operating difficulties and associated control problems are discussed.
Shear disruption of soya protein precipitate particles and the effect of aging in a stirred tank
Authors: Bell D. J. , Dunnill P.
Published: December 2004

An improvement in the resistance of isoelectric soya protein precipitate to capillary shear disruption was achieved by aging in a stirred tank. The aggregate strength was found to depend on the extent and duration of agitation prior to exposure to shear. An optimum value of an aging parameter Gt ∼ 105 was determined, where G is the rms velocity gradient in the aging vessel and tis the time of aging. The disruption of precipitate aggregates by exposure to high rates of shear for short times was dependent on the rate of shear and time of exposure. The dominant mechanism of aggregate breakup was fragmentation, with erosion occurring to a lesser extent. The size of the fragments produced by shear disruption was weakly dependent on the rate of shear, with higher rates of shear producing smaller fragments.
The immobilizaton of enzymes, bovine serum albumin, and phenylpropylamine to poly(acrylic acid)–polyethylene‐based copolymers
Authors: Beddows C. G. , Gil M. H. , Guthrie J. T.
Published: December 2004

A poly(acrylic acid)–polyethylene graft copolymer was prepared and used initially to couple to acid phosphatase, using soluble carbodiimides. Yields which were quite good were obtained with CMC but not with EDAC. The copolymers was used to couple trypsin using EEDQ. Several organic solvents were investigated for the preparation of the “activated” poly(acrylic acid) intermediate. Using the activated system, high concentrations of trypsin were bound but the relative activities were not very high. The yield was good with bovine serum albumin (BSA). When the method was used for invertase, acid phosphatase, and alkaline phosphatase, the yields were poor and the copolymer was shown to absorb protein by an ion‐exchange mechanism. However, the activated system gave a good yield of coupling to phenylpropylamine. A polyethylene‐coacrylic‐acid polymer containing 13% of acrylic acid (by weight) was then converted to the acid chloride by refluxing with thionyl chloride. The chlorinated copolymer which contained 0.7% chlorine and a thionyl‐chloride‐treated polyethylene control which contained no chlorine were investigated in immobilization studies. Such coupling involved bovine serum albumin (BSA), alkaline phosphatase, trypsin, β‐galactosidase, and invertase. Bovine serum albumin coupled well to the support, but none of the enzymes gave high levels of enzymes activity. Phenylpropylamine coupled well and all of the acid chloride groups were involved. Tyrosine reacted with 63% of the available acid chloride groups.
Enzymatic hydrolysis of cellulose and various pretreated wood fractions
Authors: Saddler J. N. , Brownell H. H. , Clermont L. P. , Levitin N.
Published: December 2004

Three strains of Trichoderma—T. reesei C30, T. reesei QM9414, and Trichoderma species E‐58—were used to study the enzymatic hydrolysis of pretreated wood substrates. ach of the culture filtrates was incubated with a variety of commercially prepared cellulose substrates and pretreated wood substrates. Solka floc was the most easily degraded commercial cellulose. The enzyme accessibility of steam‐exploded samples which had been alkali extracted and then stored wet decreased with the duration of the steam treatment. Air drying reduced the extent of hydrolysis of all the samples but had a greater effect on the samples which had previously shown the greatest hydrolysis. Mild pulping using 2% chlorite increased the enzymatic hydrolysis of all the samples. Steam explosion was shown to be an excellent pretreatment. The results indicate that the distribution of the lignin as well as the surface area of the cellulosic substrate are important features in enzymatic hydrolysis.
Modeling of bacterial growth; Formulation and evaluation of a structured model
Authors: Esener A. A. , Veerman T. , Roels J. A. , Kossen N. W. F.
Published: December 2004

Models which consider changes in the composition of biomass in response to environmental changes are called Structured models. They provide a more comprehensive description of microbial behavior than unstructured models. Compared with the unstructured modeling efforts, very little has so far been done on the theory and practice of structured model building. In most of the works reported so far, no experimental data were provided, and hence no means of testing the proposed models were offered. Others only reported macroscopic response data and not the cellular composition. In an attempt to fill some of the gaps in this field, in this work, first the general formal approach to structured modeling is developed in matrix notation. Then, a simple two‐compartmental model, i.e., a structured model describing the activity of the biomass with two variables, is described. The cell is divided into two fractions, one of which relates to the RNA fraction. The proposed model was then critically evaluated with experimental data, including the RNA data, obtained from fed‐batch and continuous‐culture experiments. The importance of using cellular structure data for model verification, i.e., RNA data in this case, is shown. Shortcomings and capabilities of the developed model are discussed.
Metabolic parameters of the earthworm Eisenia foetida in relation to temperature
Authors: Hartenstein Roy
Published: December 2004

Comparisons of rate of achieving sexual maturity, cocoon production, and growth rate at six temperatures between 15 and 30°C led to the conclusion that the earthworm Eisenia foetida can be produced optimally over the range 18‐25°C and perhaps maximally at 20°C.
Cell immobilization in k‐carrageenan with tricalcium phosphate
Authors: Wang Henry Y. , Hettwer David J.
Published: December 2004

The objectives of this research were to investigate the growth of immobilized yeast cells in k‐carrageenan gel and study the effect of trapping hydroxyapatite (tricalcium phosphate) crystals into the matrix. Using k‐carrageenan, the final number of cells per milliliter of gel is at least an order of magnitude higher than free cells per milliliter of medium. A “cell retention” theory explaining this cell concentration difference was proposed. Coexistence of yeast cells and an additional agent such as tricalcium phosphate results in sustained viability through internal pH control, increased cell loading, greater settling velocity, and enhanced ethanol production.
Fluidized‐bed fermenters: A steady‐state analysis
Authors: Andrews Graham F.
Published: December 2004

A new mathematical model is presented model is presented for use in the design and optimization of fluidized‐bed fermenters. Unlike previous models, the biomass particle size is not a required input parameter, but is predicted as a consequence of the process by which the fermenter reaches a steady state. Both tower fermenters and supported‐film bioreactors are included in the analysis. The differences between them are explained as a consequence of the different effects of added biomass on the particle settling velocity and the tendency of a fluidized bed to stratify. A detailed qualitative treatment of solids mixing allows the model to predict the varying biomass concentration through a tower fermenter and the more constant concentration in the supported film reactor. Other features of this analysis are the inclusion of an axial dispersion term to allow for different liquid mixing conditions, and the introduction of a variable transformation that eliminates the need for a computer solution. A sample design problem is included.
A study of cellobiose fermentation by a Dekkera strain
Authors: Blondin B. , Ratomahenina R. , Arnaud A. , Galzy P.
Published: December 2004

The Dekkera intermedia strain studied has the ability to ferment cellobiose. The ethanol concentration obtained was 75 g/L from 180 g/L cellobiose (80% of theoretical yield). The fermentation of more concentrated solutions of cellobiose did not proceed well.
Kinetics of yeast alcohol dehydrogenase and its coenzyme coimmobilized in a tubular flow reactor
Authors: Mazid M. A. , Laidler K. J.
Published: December 2004

Yeast alcohol dehydrogenase and nicotinamide adenine dinucleotide (NAD) were coimmobilized, with covalent attachment, to the interior surface of a nylon tube. The NAD was attahed at the N6 group of the adenine moiety; an NAD derivative was prepared and attached to free carboxyl groups at a partially hydrolyzed nylon surface. The enzyme was attached, through glutaraldehyde residues, to free amino groups on the surface. Kinetic studies were carried out in which the reduced NAD was recycled by means of phenazine ethosulfate and 2,6‐dichlorophenol indophenol. The reaction was studied over a range of flow rates and ethanol concentrations. The variation of rate with flow rate suggested that there was little diffusion control with respect to ethanol and that there was no observable inhibition by the reaction products. These conclusions were confirmed by evidence based on dimensionless parameters for the reaction and by direct inhibition experiments. The apparent Michaelis constant was lower than when only the enzyme was immobilized, suggesting that the immobilized enzyme‐coenzyme system is of high efficiency. Overall rates of reaction were lower than when there was saturation with NAD. The tube showed no measurable loss of catalytic activity over a period of one month.
Efficiency of the cyclic batch antibiotic fermentation
Authors: Guthke R. , Knorre W. A.
Published: December 2004

For a simple mathematical model of microbial product formation, the productivities of stationary and nonstationary cultivation methods (chemostat and cyclic batch) are compared. Conditions of superiority of the cyclic batch cultivation are characterized. The model includes substrate inhibition of the product formation and the age‐dependent loss of productivity of the culture.
Foam separation of DNA and proteins from solutions
Authors: Lalchev Z. , Dimitrova L. , Tzvetkova P. , Exerowa D.
Published: December 2004

Foam separation on BSA‐DNA (bovine serum albumine/deoxyribonucleic acid) and Lysozyme‐DNA systems is performed. The separation of the total protein from DNA is evaluated for dissociated chromatin solution. Foam separation for the same systems is done also by a new method of creating a pressure gradient in the Plateau‐Gibbs borders in the foam and obtaining a “dry” foam. It is shown that the effectiveness of the foam separation can be improved significantly by the application of the latter method. Some factors (pH, initial concentration of the solution, expansion factor of the foam) influencing the separation of proteins from DNA in the foam and in the residual solution are studied as well.
Recovery of ethanol from fermentation broths using selective sorption–desorption
Authors: Pitt W. W. , Haag G. L. , Lee D. D.
Published: December 2004

Industrialized nations face a critical problem in replacing the sources of liquid fuels that traditionally have been supplied by petroleum. One solution that has gained increasing support in this country is the use of ethanol produced by fermentation of renewable biomass as an extender in, or supplement to, gasoline for transportation fuel. Distillation, the present method of separating ethanol from the fermentation broth, is an energy‐intensive one and frequently uses more energy than is available from the ethanol recovered. There are many investigations under way to find alternative, less energy‐intensive techniques for the ethanol–water separation. The separations method described in this article involves the use of solid materials to preferentially remove ethanol from fermentation broths. Subsequent stripping of the ethanol from the sorbent with a dry gas reduces dramatically the energy required for the separation. Three solid sorbents have been investigated experimentally. Their sorption/desorption characteristics are described, and their incorporation in an ethanol recovery process is evaluated. Three sorbents were investigated: two commercially available divinylbenzene crosslinked polystyrene resins in bead form (one with a nominal surface area of 300 m2/g, the other with 750 m2/g) and an experimental proprietary molecular sieve with hydrophobic properties. Equilibrium adsorption isotherms for two of the sorbents were obtained at ambient temperature (21°C) for ethanol–water solutions containing up to 12 wt. % ethanol. In addition, 40°C isotherms were obtained for the polystyrene sorbents. Although different, the equilibrium isotherms for the sorbents indicated that ethanol could be preferentially sorbed from a dilute solution. Column breakthrough curves indicated very favorable kinetics. Desorption of the ethanol was readily effected with warm (60–80°C), dry nitrogen.
Electrophoretic study of the macromolecular compounds excreted by yeasts: Application to differentiation between strains of the same species
Authors: Bouix M. , Leveau J. Y.
Published: December 2004

The macromolecular compounds excreted during growth by yeasts as exocellular fractions were studied and found to contain a high proportion of carbohydrates. On the basis of the specificity of these fractions, an attempt was made to distinguish between nine strains of a single species of yeast—Saccharomyces cerevisiae. Each strain came from a different source. The electrophoretic patterns of the exocellular fractions tested made it possible to distinguish between the nine strains, on the basis of Lodder's criteria for the morphological and physiological identification of yeasts. We considered that strains giving exocellular fractions distinguishable by electrophoresis belonged to distinct clones. Consequently, this technique enables us to go further than diagnosis of the species.
Growth monitoring and control in complex medium: A case study employing fed‐batch penicillin fermentation and computer‐aided on‐line mass balancing
Authors: Mou Duen‐Gang , Cooney Charles L.
Published: December 2004

To broaden the practicality of on‐line growth monitoring and control, its application in fedbatch penicillin fermentation using high corn steep liquor (CSL) concentration (53 g/L) is demonstrated. By employing a calculation method that considers the vagaries of CSL consumption, overall and instantaneous carbon‐balancing equations are successfully used to calculate, on‐line, the cell concentration and instantaneous specific growth rate in the penicillin production phase. As a consequence, these equations, together with a feedback control strategy, enable the computer control of glucose feed and maintenance of the preselected production‐phase growth rate with error less than 0.002 h−1.
The half‐saturation coefficient for dissolved oxygen: A dynamic method for its determination and its effect on dual species competition
Authors: Hao Oliver J. , Richard Michael G. , Jenkins David , Blanch Harvey W.
Published: December 2004

A simple approach was developed to determine the half‐saturation coefficient for dissolved oxygen (KDO) for three bacteria by maintaining a constant oxygen concentration in continuous culture, and employing a dynamic method to obtain the specific growth rate (μ) for each species. Measurement of μ at selected dissolved oxygen concentrations (DO) resulted in a typical Monod curve for a plot of μ vs. DO. Values for KDO and μmax were obtained from the Lineweaver–Burk reciprocal plot. The bacteria studied included representative strains of three microorganisms isolated in pure culture from poorly settling activated sludge: two filamentous microorganisms, Sphaerotilus natans and a second Sphaerotilus sp., and an unidentified floc‐forming microorganism. The KDO values obtained for Sphaerotilus sp., S. natans, and the floc former were 0.014, 0.033, and 0.073 mg/L, respectively. Dual species competition experiments were conducted in continuous culture under low and high DO conditions. Successful growth competition by these microorganisms under DO‐limiting conditions was consistent with experimentally determined KDO values. The finding of lower KDO values for the two Sphaerotilus species, compared to the floc former, confirmed the hypothesis that these filamentous microorganisms can outgrow floc‐forming microorganisms in activated sludge when DO in the aeration basin is low.
Cultivation of E. coli in single‐ and ten‐stage tower–loop reactors
Authors: Adler I. , Schügerl K.
Published: December 2004

E. Coli was cultivated in batch and continuous operations in the presence of an antifoam agent in stirred‐tank and in single‐ and ten‐stage airlift tower reactors with an outer loop. The maximum specific growth rate, μm, the substrate yield coefficient, Yx/s, the respiratory quotient, RQ, substrate conversion, Us, the volumetric mass transfer coefficient, KLa, the specific interfacial area, a, and the specific power input, P/VL, were measured and compared. If a medium is used with a concentration of complex substrates (extracts) 2.5 times higher than that of glucose, a spectrum of C sources is available and cell regulation influences reactor performance. Both μm and YX/S, which were evaluated in batch reactors, cannot be used for continuous reactors or, when measured in stirred‐tank reactors, cannot be employed for tower‐loop reactors: μm is higher in the stirred‐tank batch than in the tower‐loop batch reactor, μm and Yx/s are higher in the continuous reactor than in the batch single‐stage tower–loop reactor. The performance of the single‐stage is better than that of the ten‐stage reactor due to the inefficient trays employed. A reduction of the medium recirculation rate reduces OTR, Us, Pr, and YX/S and causes cell sedimentation and flocculation. The volumetric mass transfer coefficient is reduced with increasing cultivation time; the Sauter bubble diameter, ds, remains constant and does not depend on operational conditions. An increase in the medium recirculation rate reduces kLa. The specific power input, P/VL, for the single‐stage tower loop is much lower with the same kLa value than for a stirred tank. The relationship kLa vs. P/VL evaluated for model media in stirred tanks, can also be used for cultivations in these reactors.
Effects of ammonia and phosphate limitation on the activated sludge treatment of calcium‐containing chemical waste
Authors: Salanitro J. P. , Sun P. T. , Thornton J. B.
Published: December 2004

Laboratory‐scale biotreaters were used to study the effects of NH3‐N and PO4‐P nutrients on the activated sludge treatment of a chemical waste containing soluble calcium (1300 mg/L). Units receiving high or low levels of NH3‐N and PO4‐P were similar in their ability to remove organic compounds from the waste. Adaptation of sludges to low PO4‐P levels (<0.1 mg/L effluent) resulted in a marked accumulation of CaCO3 in the biosolids, whereas those receiving high PO4‐P (2–4 mg/L effluent) had little CaCO3. Microscopic observations of CaCO3 containing sludges showed substantial amounts of CaCO3 crystals imbedded in the biomass. These flocs also appeared to be enriched with nonfilamentous bacterial species in contrast to flocs devoid of CaCO3 which had a floc structure of filamentous and nonfilamentous organisms. Scanning electron micrographs of flocs grown under low NH3‐N showed a microbial fibrillar network of exocellular material interconnecting cells in the floc matrix. The sludges adapted to low NH3‐N also produced higher amounts of extractable polysaccharide. CaCO3 containing biosolids were more dense, larger, and settled better (low SVI, high ISV) than flocs devoid of the precipitates. It is not known from our experiments whether PO4‐P or some inorganic or organic polymer produced by the floc bacteria are involved in inhibiting CaCO3 precipitation in the activated sludge treatment of calcium‐containing wastes.
Preparation and properties of trypsin chemically attached to EEDQ activated styrene–methacrylic acid copolymers
Authors: Telefoncu A.
Published: December 2004

Styrene–methacrylic acid copolymers of varying combinations crosslinked with p‐DVB (1–2%) and porous structure were synthesized to be used as carriers in trypsin immobilization. The styrene–methacrylic acid copolymers containing free carboxy groups were activated by conversion into the mixed carbonic anhydride with N‐ethoxycarbonyl‐2‐ethoxy‐1,2‐dihydroquinoline (EEDQ) at pH 4.0. The degree of activation of copolymers were determined from the amount of p‐aminobenzoic acid each could bind. The activated copolymers were incubated with trypsin in phosphate buffer (pH 8.0) at 4°C for 24 h. The optimum conditions for enzymatic activity measurements determined and the activity tests were carried out in 1.5 × 10−2M CaCl2 solution (pH 8.0) at 0.05 ionic strength with a pH‐stat instrument. The dependence of the activity of styrene–methacrylic acid (SMA)/trypsin derivatives to pH was investigated and it was observed that the optimum pH of the immobilized trypsin derivatives moved to the basic region compared to the native trypsin. It was found that as the ionic strength increased, the shift in the optimum pH decreased and the activity increased. The Michaelis constants for the SMA–trypsin derivatives were determined with aid of Lineweaver–Burk diagrams. The thermal, storage, and operational stabilities of SMA–trypsin derivatives were assessed. It was found that the above stabilities for all the immobilized trypsin derivatives were better than that for the native trypsin.
Fermentation monitoring by polymeric‐resin‐based microbiol assay
Authors: Seaton Jay J. , Wang Henry Y.
Published: December 2004

A polymeric‐resin‐based microbiological assay is shown to yield results consistent with classical inhibition zone theory. This novel assay is applicable to cycloheximide, an antifungal antibiotic, at concentrations below 1.0 μg/mL and up to 800 μg/mL. Addition of ethanol to the cut‐out wells of the assay plate helps to release the antibiotic and drastically increases the inhibition zone size. The antibiotic concentrations of both two component and multicomponent systems can be determined using this method. The use of polymeric‐resin beads to monitor antibiotic concentrations is shown to be an effective technique for fermentation monitoring.
Particle size reduction by breakage in biological wastewater treatment
Authors: Glasgow Larry A. , Pollock Ronald J. , Barkley William A.
Published: December 2004

Floc breakup in biological wastewater treatment occurs in response to hydrodynamic stresses imposed by aeration, recirculation, and mixing. This size reduction is of particular concern because it leads to solids carry‐over and adversely affects process controllability. A laboratory study of floc size reduction has shown how the hydrodynamic environment causes breakup and the extent to which it proceeds at particular levels of dissipation. The structure of jet flows was found to be well‐suited for the reduction of floc size.
Heat and mass transfer effects in static solid–substrate fermentations: Design of fermentation chambers
Authors: Rathbun B. L. , Shuler M. L.
Published: December 2004

An experimental device was constructed to allow nearly simultaneous measurements to be made on temperature and gas composition at different depths in a solid–substrate fermentation bed. The time‐dependent values of temperature, mol % O2 and mol % CO2 were measured at five positions in beds 6.35 cm (2.5 in.) deep. With a tempeh fermentation (Rhiopus oligosporus growing on soybeans) the temperature gradient could be as steep as 3°C/cm during active mold growth and concentration of CO2 could reach 21 vol. % in the bottom layer.
Confining mycelial growth to porous microbeads: A novel technique to alter the morphology of non‐newtonian mycelial cultures
Authors: Gbewonyo Kodzo , Wang Daniel I. C.
Published: December 2004

In an effort to alter the filamentous morphology of Penicillium chrysogenum cells, a technique was developed to confine the growth of the mycelia to porous celite beads. The pore matrix of these beads was found to be very effective for entrapping mycelial cells and spores. The entrapped spores were used to initiate the fermentations in shake flask cultures. Significant increases in final cell densities were obtained in the confined cell cultures reaching up to 60 g/L cells. This is nearly double the cell concentration attainable in free cell cultures grown in the absence of beads. Cell loadings up to 0.55 g cells per bead were obtained in the confined cell cultures. In the later stages of the fermentations, the specific oxygen uptake rates in the confined cell cultures were found to decrease with respect to free cell cultures.
A simple, sensitive, and accurate alcohol electrode
Authors: Verduyn C. , Van Dijken J. P. , Scheffers W. A.
Published: December 2004

The construction and performance of an enzyme electrode is described which specifically detects lower primary aliphatic alcohols in aqueous solutions. The electrode consists of a commercial Clark‐type oxygen electrode on which alcohol oxidase (E.C. 1.1.3.13) and catalase were immobilized. The decrease in electrode current is linearly proportional to ethanol concentrations between 1 and 25 ppm. The response of the electrode remains constant during 400 assays over a period of two weeks. The response time is between 1 and 25 min. Assembly of the electrode takes less than 1 h.
Hydrodynamics, mass transfer, and yeast culture performance of a column bioreactor with ejector
Authors: Prokop A. , Janík P. , Sobotka M. , Krumphanzl V.
Published: December 2004

A bubble column fitted with an ejector has been tested for its physical and biological performance. The axial diffusion coefficient of the liquid phase in the presence of electrolytes and ethanol was measured by a stimulus‐response technique with subsequent evaluation by means of a diffusion model. In contrast to ordinary bubble columns, the coefficient of axial mixing is inversely dependent on the superficial air velocity. The liquid velocity acts in an opposite direction to the backmixing flow in the column. The measurement of volumetric oxygen transfer coefficient in the presence of electrolytes and ethanol was performed using a dynamic gassing‐in method adapted for a column. The data were correlated with the superficial air and liquid velocities, total power input, and power for aeration and mixing; the economy coefficient of oxygen transfer was used for finding an optimum ratio of power for aeration and pumping. Growth experiments with Candida utilis on ethanol confirmed some of the above results. Biomass productivity of 2.5 g L−1 h−1 testifies about a good transfer capability of the column. Columns fitted with pneumatic and/or hydraulic energy input may be promising for aerobic fermentations considering their mass transfer and mixing characteristics.
A rapid method for detecting bacterial contamination in the presence of Penicillium and Streptomyces antibiotic fermentations
Authors: McLaughlin J. , Bruno C. F. , Forrest T.
Published: December 2004

Contamination in antibiotic fermentation processes results in major economic and process problems. The detection and elimination of contamination is a continual objective for fermentation companies. While efforts continue to eliminate contamination by improving equipment and sterile techniques, it is still imperative to have a rapid method for detecting contamination in laboratory‐stage inoculum and seed tanks. This article describes the successful studies leading to the adoption of the BACTEC, an automatic bacterial detection system, as a supplemental detection technique. The BACTEC system detects contamination by incubating samples with a selected14C‐labeled substrate or substrates. The resulting metabolism of substrate produces 14C‐labeled CO2 which is then quantified and expressed as a growth index, permitting detection of contamination more rapidly at a much earlier time than is possible with conventional detection techniques that involve Phenol red dextrose broth, streak plates, and microscopic examination techniques.
Ion exchange chromatography of proteins—predictions of elution curves and operating conditions. II. Experimental verification
Authors: Yamamoto Shuichi , Nakanishi Kazuhiro , Matsuno Ryuichi , Kamijubo Tadashi
Published: December 2004

The applicability and validity of the model developed in Part I were confirmed experimentally. In this article, various proteins were eluted both by stepwise and linear gradient elution on DEAE ion exchangers under a variety of experimental conditions. Adsorption isotherms were measured as a function of ionic strength in batch experiments. The moment method was empolyed for the determination of various parameteres such as the gel‐phase diffusion coefficient and the longitudinal dispersion coefficient. By use of these parameters and the experimentally measured ionic strength of the peak position, the number opf plates was determined according to the method described in Part I. Theoretical elution curves were calculated with the experimentally measured adsorption eqluilibria and the number of plates. Good agreement was observed between theory an experiments. Various factors affecting the separation were investigated. It was found that the effect of the number of plates for salts, N′p, was negligible except the case of stepwise elution of high ionic strength buffer. When elution curves were symmetrical, the widths of the elution curves were inversely proportional to the square root of the number of plates of proteins, Np, as in other chromatographic techniques. A simple graphical method for prediction of the peak position in linear gradient elution described in Part I was found applicable when the elution curves were symmetrical. A useful correlation of prediction of the peak width in a linear gradient elution was proposed on the basis of the approximate solution derived in Part I of this study. This graphical method and correlation permit easy prediction of the peak position and peak width in linear gradient elution in the case of symmetrical elution curves.
Enzyme management in the iotech process
Authors: Sinitsyn A. P. , Bungay H. R. , Clesceri L. S.
Published: December 2004

In the Iotech process, steam explosion of wood chips potentials hydrolysis of the cullulose by enzymes. A small portion of the exploded wood is used as substrate for the production of enzymes for hydrolysis of the remaining wood. Explosions conditions degrade some of the hemicellulose, creating factors (probably related to furfural) that impair enzymatic hydrolysis and destablized the cellulases. Fortunately, simple washing with water paremits more rapid hydrolysis while enzyme stability is greatly improved. Enzymes can be recovered from the hydrolysis residue by adjusting the pH to neutrality, and additional enzymes from hydrolysis filtrate can be adsorbed on fresh exploded wood en route to hydrolysis. A simple mass balance calculation shows proportions of various activities in a mix of fresh and recycled enzymes.
Steady‐state approximation of enzyme activation and inhibition
Authors: Okamoto Masahiro , Takeda Youko , Aso Yoichi , Hayashi Katsuya
Published: December 2004

This article deals with the effects of the initial concentration of effector (inhibitor or activator) on the steady‐state approximation of enzyme kinetics. The results could be summarized as follows: (1) In competitive inhibition, the increase in the initial concentration of inhibitor led to the reduction of steady state time. (2) In noncompetitive and uncompetitive inhibitions, the steady state time was not changed with the increase in the initial concentration of inhibitor. (3) In nonessential activation, the increase in the initial concentration of activator led to the reduction of steadystate time. (4) It was specially noted that in nonessential activation, even if the reaction is in the steady‐state, activation constant (KA) can not be determined exactly unless the initial concentration of activator is very small.
Kinetics of multilayer immobilized enzyme‐filter reactors: Behavior of urease‐filter reactors in different buffers
Authors: Goldstein Leon , Levy Mordechai , Shemer Lev
Published: December 2004

A sequential model which describes the kinetic behavior of multilayer immobilized‐enzyme filter reactors for systems obeying the Michaelis‐Menten scheme and various types of inhibition by product and by substrate is proposed. The model was varified experimentaly using a single enzyme‐filter‐substrate system—urease bound to nylon‐filter disks acting on urea—in different buffers to obtain the various inhibition patterns.
Solubility and selective crystallization of lactose from solutions of its hydrolysis products glucose and galactose
Authors: Bourne J. R. , Hegglin M. , Prenosil J. E.
Published: December 2004

A high degree of conversion is desired when lactose is hydrolyzed to glucose and galactose. This produces, however, a high concentration of galactose, which is inhibitory for the enzyme catalyst (β‐galactosidase). The inhibition can be reduced by limiting the conversion per pass over the enzyme (e.g. to ca. 50%), separating unconverted lactose from the reactor effluent, and recycling it to the reactor inlet. (This allows the overall conversion to be raised to ca. 80–90%). The solubilities of lactose, glucose, and galactose have been determined at various temperatures and for sugar mixtures having different concentrations and degrees of hydrolysis. Various cooling crystallizations have defined convenient and simple processes for the selective separation of lactose from its hydrolysis products.
NO2 Sensor which uses immobilized nitrite oxidizing bacteria
Authors: Okada Tadashi , Karube Isao , Suzuki Shuichi
Published: December 2004

A biosensor consisting of immobilized nitrite oxidizing bacteria and an oxygen electrode has been developed for the amperometric determination of NO2 (nitrogen dioxide) gas. The response time for the determination of NO2 was within 3 min. A linear relationship was observed between the current decrease and the NO2 concentration below 255 ppm. The minimum concentration for the determination of NO2 was 0.51 ppm. The current decrease was reproducible within ±4% of the relative error. The selectivity of the microbial sensor for NO2 was satisfactory. The current output of the sensor was almost constant for more than 24 days and 400 assays.
Precipitation, chelation, and the availability of metals as nutrients in anaerobic digestion. II. Applications
Authors: Callander I. J. , Barford J. P.
Published: December 2004

The relative importance of the individual effects of precipitation and chelation of metal ions in anaerobic digestion is assessed. Experimentally determined soluble metal ion levels are compared with predicted levels obtained by using a previously described methodology.1 It is found that soluble metal complexes may increase the level of soluble metals in the presence of CO and S2− by a factor of up to 104. The formation of a soluble complex may increase or decrease the availability of the metal ion in question for microbial uptake. Two case studies are presented, one using a defined medium and one a complex medium. It is possible, in the case of the defined medium, to accurately predict the free metal ion concentration using the methodology previously developed.1 While the identification of the presence of natural chelating compounds in a complex medium is not routinely possible, the significant discrepancy between the measured level of the soluble metal ion Fe2+ and the calculated level in the case studies presented indicates that natural chelating compounds may play a vital role in providing available metal ions to the microorganisms of an anaerobic digester.
A new sensor—the “filtration Probe”— for quantitative characterization of penicillin fermentation. III. An automatically operating probe
Authors: Nestaas Eirik , Wang Daniel I. C.
Published: December 2004

The filtration characteristics of the penicillin broth can be monitored semicontinuously using an automatic filtration probe. This probe operates aseptically and the broth samples (filtrate and filter cake) are recycled to the fermentor after each filtration. The collected data—filtrate volume and filter cake volume versus filtration time—can be related to the total biomass concentration in the fermentor.
Improving immobilized biocatalysts by gel phase polymerization
Authors: Kuu W. Y. , Polack J. A.
Published: December 2004

A new method is presented for the treatment of gel‐type supports, used for immobilizing microbial cells and enzymes, to obtain high mechanical strength. It is particularly useful for ethanol fermentation over gel beads containing immobilized viable cells, where the beads can be ruptured by gas production and the growth of cells within the gels. This method consists of treating agar or carrageenan gel with polyacrylamide to form a rigid support which retains the high catalytic activity characteristic of the untreated biocatalysts. The size and shape of the biocatalyst is unaffected by this treatment. The method involves the diffusion of acrylamide, N,N′‐methylenebisacrylamide and β‐dimethylaminopropionitrile (or N,N,N′,N′‐tetramethyl‐ethylenediamine) into the performed biocatalyst beads followed by the addition of an initiator to cause polymerization within the beads. Treated gels have been used for the continuous fermentation of glucose to ethanol in a packed column for over two months. During this operation, the gel beads maintained their rigidity, and the maximum productivity was as high as 50 g h−1 L−1 gel. There was no appreciable decay of cell activity.
Rates of glucose oxidation with a column reactor utilizing a magnetic field
Authors: Sada Eizo , Katoh Shigeo , Shiozawa Masami , Matsui Ichiro
Published: December 2004

Rates of glucose oxidation were measured with the use of a fluidized‐bed column placed in a magnetic field and magnetite‐containing beads of immobilized glucose oxidase and catalase. Its performance was predicted from the volumetric coefficient for liquid‐phase mass transfer and the kinetic constants for glucose oxidation. Effusion of beads was negligible under the operating conditions employed.
Dynamics of biodegradation of 2,4‐dichlorophenoxyacetate in the presence of glucose
Authors: Papanastasiou A. C. , Maier W. J.
Published: December 2004

It has been observed experimentally that the biodegradation of 2,4‐dichlorophenoxyacetate (2,4‐D) is inhibited by the presence of glucose. However, this effect is masked by the fact that larger concentrations of active biomass are produced when glucose is available. The implication of such a “mixed” growth in a continuous flow system is that much higher dilution rates can be applied for an efficient chlorinated‐organic removal when other conventional substrates are present. The mean cell residence time is reduced and the area of stability of the process is extended into higher dilution rates, as well as into higher influent concentrations. Finally, the presence of the mixed substrate changes dramatically the “washout” conditions for both substrates. All these facts point out that the biodegradation of chlorinated organics is more efficient in a mixed substrate environment.
Fluorescence and photoacoustic spectroscopy of immobilized thylakoids
Authors: Thomasset Brigitte , Barbotin Jean‐Noël , Thomas Daniel , Thomasset Thierry , Vejux Alain , Jeanfils Joseph
Published: December 2004

The O2 evolution activity of immobilized chloroplast membranes in different environments (albumin‐glutaraldehyde matrix, urethane polymer and alginate beads) is presented. As previously shown, the stability of photosystem II (PS II) of lettuce thylakoids appears to be increased by the immobilization process. For understanding such stability, some spectral investigations have been made about the energy distribution between the immobilized photosystems. The low‐temperature (77 K) fluorescence emission and photoacoustic spectroscopy are well adapted to solid particle studies. Especially, it has been shown that the fluorescence ratio (F735/F695) and photoacoustic ratio (PA676/PA440) are good indicators of the functional level of native and immobilized thylakoids. Such ratios are also given after storage and after continuous illumination conditions. Some results about the role played by glutaraldehyde (in the case of albumin‐glutar‐aldehyde matrix) in the stabilization process are also reported.
Two‐stage continuous fermentation of Saccharomycopsis fibuligeria and Candida utilis
Authors: Admassu Wudneh , Korus Roger A. , Heimsch Richard C.
Published: December 2004

Biomass production and carbohydrate reduction were determined for a two‐stage continuous fermentation process with a simulated potato processing waste feed. The amylolytic yeast Saccharomycopsis fibuligera was grown in the first stage and a mixed culture of S. fibuligera and Candida utilis was maintained in the second stage. All conditions for the first and second stages were fixed except the flow of medium to the second stage was varied. Maximum biomass production occurred at a second stage dilution rate, D2, of 0.27 h −1. Carbohydrate reduction was inversely proportional to D2, between 0.10 and 0.35 h −1.