Showing papers in "Biotechnology and Bioengineering in 1967"
TL;DR: A rapid and internally consistent technique to measure the volumetric oxygen transfer coefficient in fermentation systems suggests that O 2 uptake rate will vary if a prolonged (2-10 min.) O 2 starvation occurs.
Abstract: A rapid and internally consistent technique has been developed to measure the volumetric oxygen transfer coefficient, k L a, in fermentation systems. The method consists of tracing the dissolved O 2 concentration of the fermentation broth during a short interruption of the aeration. The O 2 concentration trace thus obtained can be analyzed to determine the values of k L a. Additional experiments on prolonged O 2 starvation, carried out to find the limitation of the technique, suggest that O 2 uptake rate will vary if a prolonged (2-10 min.) O 2 starvation occurs.
318 citations
TL;DR: On the basis of the NMR and mass spectra of geosmin and its acid transformation product, argosmin, tentative partial structures have been proposed for both.
Abstract: Geosmin, an earthy smelling substance, has been obtained from several actinomycetes in addition to those previously reported. On the basis of the NMR and mass spectra of geosmin and its acid transformation product, argosmin, tentative partial structures have been proposed for both.
278 citations
TL;DR: In this article, the effect of alcohol concentration on yeast growth was studied in a continuous fermentor with a continuous yeast feed supplemented with pure alcohol at pH 3.6 and 4.05.
Abstract: The alcoholic fermentation of grape juice by a wine yeast was studied batchwise at pH 3.6 and 4.05 to develop kinetic equations relating cell concentration, N, to product concentration, P. In the exponential growth phase
where A, B, and C are constants, and μ is the specific growth rate. In the stationary phase, where the cell population is constant,
was found to apply. This equation, which incorporates a stoichiometric constant, Pm, predicted correctly the operation of a continuous fermentor at pH 3.6 and at 4.05. To study more fully the effect of alcohol concentration on yeast growth, a continuous fermentor was used in which the grape juice feed was supplemented with pure alcohol. At pH 3.6 the specific growth rate varied as,
There was no growth inhibition below an alcohol concentration of 2.6 g./100 cc., but inhibition was complete above 6.85 g./100 cc. This is a modified form of the relation suggested by Hinshelwood.1 The data suggest that growth in batch culture was limited not only by alcohol but also by some other factor, probably a nutritional deficiency.
184 citations
TL;DR: Shoyu is the best, known oriental food fermentation, and it is very widely used as a flavoring agent, and a large number of additional ones not so well known outside the Orient, whose products serve as seasoning or flavoring agents.
Abstract: For centuries, diverse plant and animal materials have been fermented by various bacteria, yeasts, and fungi to make excellent foods. The kinds of micro organisms used in traditional fermentation are restricted to a relatively few genera, including Aspergillus, Rhizopus, Mucor, Actinomucor, Monascus, Saccharomyces, Neurospora, Acetobacler, Bacillus, and Lactobacillus. The two principal advantages of food fermentations over other processes are to add flavor and to prevent spoilage. Fermented fish is a common food in the Orient and may have been the first product made by fermentation. Flavor is especially important in vegetable diets based on bland foods such as rice. Shoyu is the best, known oriental food fermentation, and it is very widely used as a flavoring agent. Be sides this fermentation, there are a large number of additional ones not so well known outside the Orient, whose products serve as seasoning or flavoring agents. Miso and natto are prepared from soybeans in Japan. Sufu is a cheese like product made from soybean milk in China. Tempeh and ontjom are Indonesian foods prepared from soybeans and peanuts, respectively. These food fermentations are discussed with emphasis on how they are produced and the flavor formed.
156 citations
TL;DR: The structured models account for the dependence of growth on the past, history of the cells; thus they predict all growth phases observed in batch cultures, whereas the unstructured models do not predict a lag phase.
Abstract: Mathematical models for microbial growth in batch and continuous cultures are formulated. The models have been referred to as distributed models since the microbial population in a culture is looked upon as protoplasmic mass distributed uniformly throughout the culture. Growth is regarded as the increase in this mass by conversion of medium components into biological mass and metabolic products. Two sets of models have been presented. The first arise from introducing additional considerations into the model proposed by Monod to account for the stationary phase and the phase of decline in a batch culture. These have been referred to as unstructured, distributed models since they do not recognize any form of structure in the protoplasmic mass. The models in the second set are referred to as structured, distributed models. Structure is introduced by considering the protoplasmic mass to be composed of two groups of substances which interact with each other and with substances in the environment to produce growth. The structured models account for the dependence of growth on the past, history of the cells; thus they predict all growth phases observed in batch cultures, whereas the unstructured models do not predict a lag phase. The full implications of the models for continuous propagation, as determined by the method of stability analysis and transient calculations, are discussed. The models prediet a number of new results and should be confronted with experiments.
117 citations
117 citations
TL;DR: By employing a DEAE‐Sephadex–aminoacylase column, conditions for continuous optical resolution of acyl‐DL‐amino acids were investigated and the highest rate of hydrolysis of both substrates was attained.
Abstract: Conditions for the preparation of an aminoacylase column using DEAE‐Sephadex as a carrier were investigated. The aminoacylase column having the highest activity was obtained when 7500 μmoles/hr. of partially purified aminoacylase was charged into a column packed with 9 ml. of DEAE‐Sephadex A‐25 (bead type, hydroxy form). By employing a DEAE‐Sephadex–aminoacylase column, conditions for continuous optical resolution of acyl‐DL‐amino acids were investigated. When a solution of 0.2M acetyl‐DL‐methionine (pH 7.0, containing 5 × 10−4M Co2+) or 0.2M acetyl‐DL‐phenylalanine (pH 6.0, containing 5 × 10−4M Co2+) was passed through the aminoacylase column at the flow rate of SV = 2.5 or 2.0, respectively, at 50°C., the highest rate of hydrolysis of both substrates was attained. From the column effluents, enzymatically hydrolyzed L‐methionine and L‐phenylalanine were isolated in a good yield.
106 citations
TL;DR: Steam-sterilizable membrane probes that are virtually maintenance-free and capable of operation for over 1 year are described.
Abstract: Steam-sterilizable membrane probes that are virtually maintenance-free and capable of operation for over 1 year are described. The probes can withstand repeated steam sterilizations. They have a silver cathode, a lead anode, an acetate buffer, and a Teflon membrane. The probes have a linear response from below 0.00002 to over 0.2 atm. of oxygen.
98 citations
TL;DR: The results of a survey of several mining operations have shown in every instance typical T. ferrooxidans bacteria to be present in the leaching solutions as mentioned in this paper, the numbers of bacteria found are in general what, one would expect considering the chemical reactions occurring in these processes.
Abstract: The results of our survey of several mining operations have shown in every instance typical T. ferrooxidans bacteria to be present in the leaching solutions. The numbers of bacteria found are in general what, one would expect considering the chemical reactions occurring in these processes. A major difficulty is encountered when one considers the complex and unknown series of events which occur, as the bacteria-bearing, acidic, ferric-ion solution penetrates the massive ore dumps. Laboratory studies show microbial activity to be the major cause of rapid solubilization of copper sulfide ores. Field studies suggest that microbial activity cannot explain all observations in a typical leaching operation.
90 citations
TL;DR: In this paper it will be shown that the chemostat system might show an overshoot (or an underswing) with respect to changes in cell and substrate concentrations, depending on the extent to which the system might be disturbed from steady‐slate conditions.
Abstract: This paper deals with a theoretical study on the dynamic, character of the chemostat system. It. is primarily based on the Monod model for growth limitation, although certain more complex models are considered. Since the Monod model is described in terms of two variables, an analysis by use of a phase plane plot will show the various possible types of behavior theoretically expected for transient conditions of the system. In this paper it will be shown that the chemostat system might show an overshoot (or an underswing) with respect to changes in cell and substrate concentrations, depending on the extent to which the system might be disturbed from steady-slate conditions. Other types of transient behavior ran also be expected when one of the system parameters such as dilution rate or input substrate concentration is disturbed in a stepwise manner. The simple Monod chemostat model was found never to oscillate in either a damped or a sustained manner as has been experimentally reported. Discussion is included about the transient behavior of other chemostat models such as that involving a variable yield coefficient, i.e., including the effect of cell maintenance requirements.
78 citations
TL;DR: The kinetic behavior of heterogeneous microbial populations was studied in a continuous flow completely mixed reactor operated at various dilution rates and substantiated the use of the single phase relationship between growth rate and substrate concentration described by the Monod equation.
Abstract: The kinetic behavior of heterogeneous microbial populations was studied in a continuous flow completely mixed reactor operated at various dilution rates. Glucose was used as the growth-limiting nutrient. The physiological growth parameters for cells harvested from continuous flow reactors were determined using batch experiments. It, was found that the growth parameters, maximum growth rate (μm), saturation constant (ks), and cell yield (Y) vary for each dilution rate, and cannot be considered as precise constants in depicting the kinetic behavior of heterogeneous populations. In addition, it was found that the yield coefficients obtained from batch experiments were always lower than those obtained from continuous flow experiments. Levels of substrate and biological solids calculated for different dilution rates using growth constants from batch experiments did not agree with the experimental values observed in steady-state experiments. However, when the yield values from, the continuous flow experiments were used in conjunction with batch values for μm and ks the theoretical and experimental dilute-out curves agreed fairly closely (within the range needed for engineering prediction) until the culture began to wash out of the unit. In general, the data substantiated the use of the single phase relationship between growth rate and substrate concentration described by the Monod equation, μ = μmS/(ks + s).
TL;DR: In this paper, the authors measured the contribution of Thiobacillus ferrooxidans in low-grade copper sulfide ores, and found that at least three contributions are made by the bacterium: enzymatic oxidation and consequent solubilization of insoluble sulfides; regeneration of ferric lixiviant for chemical oxidation and solubilation of soluble sulfide; and partial fixation of externally introduced iron.
Abstract: In bacterial extraction of copper from low-grade copper sulfide ores, at least three contributions are made by Thiobacillus ferrooxidans. They are: (1) enzymatic oxidation and consequent solubilization of insoluble sulfides; (2) regeneration of ferric lixiviant for chemical oxidation and solubilization of insoluble sulfides; and (3) partial fixation of externally introduced iron in the ore. Although it is not possible at the present time to measure each of these contributions separately, it is possible to measure the combined contributions. Such measurements reveal a strong dependence of extraction efficiency on various physical, chemical, and biological factors. The following physical factors may affect the rate of bacterial copper extraction: particle-size of ore, oxygen and carbondioxide supply, oxidation-reduction potential, pH, temperature, adsorption and ion exchange capacity of ore, and surface tension effects. The following chemical factors may influence the rate of copper extraction: the mineralogy of the ore, the nature of the gangue, the distribution of the sulfide minerals in the host rock, the external supply of ferrous or ferric iron, and the availability of inorganic and organic nutrients. Finally, the following biological agents in addition to T. ferrooxidans may influence the rate of copper extraction: fungi, protozoa, Thiobacillus thiooxidans, and heterotrophic bacteria. Proper control of these various factors is essential for efficient bacterial extraction of copper from low-grade ore. It is recognized that the foregoing environmental factors also influence chemical copper extraction.
TL;DR: In this article, the authors investigated if fully safe operation at all times, by oxygen concentration control, is possible in agitated and sparged batch fermentors, and concluded that it is possible, cultures being able to grow exponentially without substrate limitation by the gaseous phase nutrients.
Abstract: The cultivation of aerobic, methane‐utilizing, microbial cells by submerged culture techniques, in an entirely mineral salts medium, with a view to their use as an edible protein source is discussed. Particular emphasis is placed on the potentially explosive nature of gaseous mixtures containing methane and oxygen. The experiments described investigate if fully safe operation at all times, by oxygen concentration control, is possible in agitated and sparged batch fermentors. Appreciable wastage of methane is prevented by gaseous‐phase recirculation. It is concluded that fully safe operation is possible, cultures being able to grow exponentially without substrate limitation by the gaseous‐phase nutrients.
TL;DR: Studies on a fermentation process were conducted in 20‐1, stainless steel fermentors, without baffles, and under optimal conditions yields of mannitol approached 50% of the glucose consumed.
Abstract: Mannitol has long been known as a product of glucose metabolism by some strains of Aspergillus. Apparently no concerted effort, has been made to develop a practical fermentation process to make mannitol. Work at the Northern Laboratory has shown that nearly all strains of white Aspergillus produce significant amounts of mannitol; many strains of black Aspergillus also have this characteristic. Aspergillus candidus NRRL 305 is an exceptionally good mannitol producer. Studies on a fermentation process were conducted in 20-1, stainless steel fermentors, without baffles. Czapek-Dox medium, modified by addition of corn meal, yeast extract, and enzymatically hydrolyzed casein was the most satisfactory medium tested. Suitable increments of glucose were fed daily to the fermentors. The duration of the fermentation was from 10 to 16 days. The effects of agitation, aeration, temperature, and pH of the medium were studied. Under optimal conditions yields of mannitol approached 50% of the glucose consumed.
TL;DR: Once the enzymes required for lactose utilization had been induced, this ability to use lactose was retained, even in the absence of lactose, for very long periods of time under continuous conditions.
Abstract: A strain of Klebsiella aerogenes was selected which gave marked diauxic growth in a batch system on a mixture of glucose and lactose in a simple salts medium; the diauxic lag was 15–20 hr. at 30°C. The growth of this organism on glucose and lactose was studied in a single-stream two-stage continuous-stirred fermentor system over a wide range of flow rates. Glucose was metabolized instantaneously to give very low reactor concentrations at all flow rates, but the time lag before lactose was attacked, when present for the first time, was never less than 40 hr. at low feed rates, rising to 60 hr. at higher rates. The adaptation to lactose of cells in the first vessel lagged behind that in the second vessel but eventually both sugars were completely utilized in the first vessel except at very high dilution rates. At these feed rates, lactose utilization was not only prevented completely in the first vessel but also could be delayed almost indefinitely in the second vessel at the highest dilution rates; thus the lactose passed unchanged through both vessels. Once the enzymes required for lactose utilization had been induced, this ability to use lactose was retained, even in the absence of lactose, for very long periods of time under continuous conditions. Thus on presenting lactose for the second and subsequent occasions it was immediately metabolized. The significance of these results is discussed.
TL;DR: The results indicate a rather wide prevalence in nature of hydrocarbon-oxidizing bacteria capable of fixing atmospheric nitrogen, and suggests further consideration of applying selected petroleum residua to soils in order to increase the agricultural potential by nitrogenfixing processes as discussed by the authors.
Abstract: Microorganisms have been found which concomitantly convert hydrocarbons, selected naphthenic acids, and atmospheric nitrogen into cellular substance. Bacteria are included in the genera Pseudomonas, Mycobacterium, and Azotobacter. Carbon sources utilized include the hydrocarbons methane, n-butane, n-tetradecane, toluene, and a naphthenic acid, cyclohexane-carboxylate. Uptake of isotopic nitrogen was employed as a criterion of nitrogen fixation. The results indicate a rather wide prevalence in nature of hydrocarbon-oxidizing bacteria capable of fixing atmospheric nitrogen. Their occurrence helps explain the high concentration of organic nitrogen commonly found in soils exposed to gas leakage from pipelines or natural-gas seeps, and suggests further consideration of the possibility of applying selected petroleum residua to soils in order to increase the agricultural potential by nitrogen-fixing processes.
TL;DR: The yeast S. cerevisiae was grown on dilute, chemically defined media in continuous culture with either glucose or ammonium sulfate as the growth-limiting ingredient, and dilution rate step changes gave non-oscillatory transient responses.
Abstract: The yeast S. cerevisiae was grown on dilute, chemically defined media in continuous culture with either glucose or ammonium sulfate as the growth-limiting ingredient. Changes in dilution rate or glucose concentration induced decaying oscillations in the numbers of yeast growing on ammonium sulfate-limited media. Spot checks indicated that Cell dry weight and Kjeldahl nitrogen followed the cell numbers during these oscillations. With glucose-limited media, there was no response to step changes in ammonium sulfate concentration, and dilution rate step changes gave non-oscillatory transient responses.
TL;DR: An a flatoxin‐producing isolate of Aspergillus flavus was found to be a consistent producer of aflatoxin on all substrates which supported the growth of the mold.
Abstract: An aflatoxin-producing isolate of Aspergillus flavus was found to be a consistent producer of aflatoxin on all substrates which supported the growth of the mold. In competition with six other selected molds, this isolate was dominant except with one species of Penicillium. Aflatoxin production was parallel to the extent of A. flavus growth whether effected by substrate or competition.
TL;DR: Interfacial phenomena in adhesion of Chlorella alga strain to glass surfaces in simple ionic solutions, discussing zeta potential and additives effect as mentioned in this paper, and discussing additive effect.
Abstract: Interfacial phenomena in adhesion of Chlorella alga strain to glass surfaces in simple ionic solutions, discussing zeta potential and additives effect
TL;DR: In this article, the concentration and retention of 137Cs by unicellular diatoms, filamentous green algae, and filamentous blue-green algae were demonstrated under both batch and continuous-flow culture conditions.
Abstract: Differences in the concentration and retention of 137Cs by unicellular diatoms, filamentous green algae, and filamentous blue-green algae were demonstrated under both batch and continuous-flow culture conditions. 137Cs concentration factors were generally higher by a factor of 2 in batch tests than in continuous flow tests. In retention studies, 137Cs was desorbed more rapidly from algae under continuous-flow conditions. Studies with blue-green algae indicate that 137Cs concentrations in the various species were more closely related to the surface-to-volume ratios of algal cells than to the systematic relationships of the three species. Continuous-flow studies indicated no differences among three species of filamentous green algae in the concentration of 137Cs, 65Zn, and 85Sr. However, the average concentration factors of the radionuclides were considerably different: 3800 for 65Zn, 460 for 137Cs, and 230 for 85Sr. These radionuclides were rapidly desorbed following the transfer of algae to nonradioactive media. The desorption rate was inversely related to the concentration rate.
TL;DR: A continuous culture apparatus of 5‐liter capacity is described which is capable of control of dissolved oxygen and combined turbidostat and constant feed operation permit control of cell population density and one or more nutrients.
Abstract: A continuous culture apparatus of 5-liter capacity is described which is capable of control of dissolved oxygen. Combined turbidostat and constant feed operation permit control of cell population density and one or more nutrients. A system for the measurement of oxygen uptake and CO2 output is described. Sufficient detail is supplied to enable construction and operation of the apparatus.
TL;DR: In this article, the authors have isolated an organism which has not, yet, yet been identified; it is a comparatively large Bacillus, which thriven in a medium of mineral salts saturated with a gaseous mixture of 40%, methane (or natural gas), 40% oxygen, 15% nitrogen, and 5% carbon dioxide.
Abstract: From soil and from the plant Elodea, we have isolated an organism which has not, yet been identified; it is a comparatively large Bacillus, which thriven in a medium of mineral salts saturated with a gaseous mixture of 40%, methane (or natural gas), 40% oxygen, 15% nitrogen, and 5% carbon dioxide. The isolated cells have amino acid and vitamin contents comparable to, or, in some cases greater than, those found in such nutrients as yeast, fish meal, or milk solids.
TL;DR: The presence of bacteria, compared to pure surfactant solutions, produces lower collapsed foam volumes; the foam volumes have a strong influence on the separations achieved with the various species, with enrichment ratiosranging from 27 to 3088 and residual ratios ranging from 0.001 to 0.247.
Abstract: An experimental investigation is presented of the foam separation of six species of bacteria: Escherichia coli, Serratia marcescens, Proteus vulgaris, Pseudomonas fluorescens, Bacillus cereus, and Bacillus subtilis var niger. A cationic surfactant, ethylhexadeeyldimethylammonium bromide is used and results are evaluated in terms of total cell count, using a membrane filtration technique. From similar neutral distilled water suspensions of the pure cultures (approximately 107 cells/ml.) and using the same operating conditions, ratios of cell concentrations in the residual suspensions to those in the initial suspensions range from 0.0013 for Bacillus subtilis var niger to 0.25 for Serratia marcescens. The presence of bacteria, compared to pure surfactant solutions, produces lower collapsed foam volumes; the foam volumes have a strong influence on the separations achieved with the various species, with enrichment ratios ranging from 27 to 3088 and residual ratios ranging from 0.001 to 0.247.
TL;DR: In this article, a motor-driven air sparge pipe is used to give a variable point of entry of the air stream into the culture liquid and hence a variable gas dispersion and gas-liquid contact time.
Abstract: A method for the control of dissolved oxygen tension in growing microbial cultures is described. The apparatus consists of a motor-driven air sparge pipe which may be lowered or raised to give a variable point of entry of the air stream into the culture liquid and hence a variable gas dispersion and gas–liquid contact time. Control of the sparge pipe position is by means of a feedback control loop consisting of a dissolved oxygen probe, an on/off controller, and a reversing electric motor which drives the sparge pipe. The difficulty presented by the relatively slow response of the oxygen probe has been overcome by incorporating an adjustable rate of control action.
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TL;DR: A description of a large glass vessel suitable for growing algae and other microorganisms in shaken culture is given in this paper, where the main feature is the coneshaped base around which water circults when the flask is shaken on a reciprocal mechanism.
Abstract: A description is given of a large glass vessel suitable for growing algae and other microorganisms in shaken culture. The main feature of the flask is the coneshaped base around which water circultes when the flask is shaken on a reciprocal mechanism.
TL;DR: In this article, the bacterial degradation of catechol, 3 methylcatechol and protocatechuic acid has been studied in detail and a general sequence has been proposed for the microbial oxidation of dihydroxy aromatic compounds.
Abstract: The bacterial degradation of catechol, 3‐methylcatechol, 2,3‐dihydroxy‐β‐phenylpropionic acid, and protocatechuic acid has been studied in detail. From the results obtained a general sequence has been proposed for the microbial oxidation of dihydroxy aromatic compounds.
TL;DR: In this article, the design and operational characteristics of a sell-priming aerator are described, and the aerator works without a compressor, sucking the desired air quantity into the tank and distributes it uniformly and in very fine bubbles over a certain cross-section.
Abstract: The design and operational characteristics of a sell-priming aerator are described. The aerator works without a compressor. H sucks the desired air quantity into the tank and distributes it, uniformly and in very fine bubbles over a certain cross-section. The design and operational characteristics of a mechanical defoamer are described. The defoamer is mounted to the top of the fermentation tank and separates foam by centrifugal force into air and liquid. It is capable of handling foams of different composition and quality without, the addition of anti foam agents. Using submerged vinegar fermentation, production of baker's yeast., and industrial waste, water treatment as examples, the performance of aerators and defoamers of different, sizes is discussed.
TL;DR: In this paper, submerged acetification experiments were performed to determine conditions necessary for the production of a satisfactory vinegar from waste pineapple juice using a pure culture inoculum and showed that vinegar containing up to 7% by weight of acetic acid could be produced in less than 24 hours with a conversion efficiency greater than 90% in both laboratory and pilot plant equipment.
Abstract: Submerged acetification experiments were performed to determine conditions necessary for the production of a satisfactory vinegar from waste pineapple juice using a pure culture inoculum. Vinegars containing up to 7%, by weight of acetic acid could be produced in less than 24 hr. with a conversion efficiency greater than 90% in both laboratory and pilot plant equipment. None of the bacterial nutrients added to the juice improved either the rate of production or the yield of acetic acid. Oxygen transfer during the process is discussed.