Theoretical analysis of the continuous two-stage process of the biosynthesis of a metabolic product

A mathematical model for continuous biosynthesis of a metabolite in a battery of two apparatuses with ideal agitation is described and analysed. In the first apparatus of the battery it is advisable to maintain a high specific rate of culture growth for continuous accumulation of young active biomass while in the second apparatus a low growth rate is expedient which provides a change in the culture metabolism to biosynthesis of the required product. To make the continuous two-stage process efficient, it is necessary to add an extremely concentrated solution of the nutrients to the second apparatus of the battery. Influence of the oxygen transport velocity on the maximum attainable concentration of the biomass and the process capacity by the required product was studied.     

A TWO LITRE SCALE CONTINUOUS CULTURE APPARATUS FOR MICRO-ORGANISMS

SUMMARY: The design and construction of a continuous culture apparatus with a 2 1. culture vessel are described. Aeration is achieved by means of a mechanical stirrer and injected air, automatic temperature and pH control are features of the apparatus, and foaming is controlled by adding antifoam through a manually operated valve. A high degree of agitation ensures that good mixing takes place. Accurate and easily variable control of the medium flow rate is obtained by means of the Mariotte bottle principle. The apparatus can be operated continuously with freedom from contamination for periods in excess of 1000 hr.     

Preparation ofClostridium septicum antigen for hyperimmunization of horses using a dialyzed culture

The preparation of toxic cultures of Clostridium septicum is described, using an apparatus with a straight dialysis tubing, where the medium is filled both into the nutrition and cultivation space of the apparatus. Using the cultivation to nutrition volume rate 1:2, mean titre of lethal antigen in filtrates 3.86 limes mortis per mL and 300 dosis lethalis minima per Lm was obtained in comparison with the values of 2.22 and 150 respectively in flask filtrates. Native filtrates of dialyzed cultures were better antigens for hyperimmunization of horses than the culture filtrates from flasks.     

An apparatus for the continuous culture of bacteria at constant generation times

Summary An apparatus for continuous culture of bacteria at constant generation times is described, analogous toNovick andSzilard's “chemostat” and the apparatus ofMonod. Detailed instructions for the use of the apparatus are given and a method for the determination of the vessel constant is described. The theory and the interesting possibilities of the apparatus for a number of fundamental problems in bacteriology are shortly discussed.     

The Effect of Carbonation, Benzoic Acid and pH on the Growth Rate of a Soft Drink Spoilage Yeast as determined by a Turbidostatic Continuous Culture Apparatus

Summary: A turbidostatic continuous culture apparatus is described, which has been used to determine the effect of variations in carbonation, benzoic acid and pH on the growth rate of a soft drink spoilage yeast. Results are presented and a model is derived which, it is believed, enables the spoilage potential of many carbonated soft drinks to be predicted.     

Working design for a 5-liter controlled continuous culture apparatus

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.     

An automatic apparatus for continuous suspension culture with a concentrating device

A chemostat in which mammalian cells can be raised in continuous suspension culture is described. It is constructed from commercially available parts. This apparatus has the advantage over earlier models in that the medium can be pumped off free of cells, thus suddenly increasing the cell concentration in the culture. The apparatus has been successfully used in studies on contact inhibition.     

An automated recording incubator for tube culture of microorganisms

Studies on the development of an automated incubator which can perform the operations commonly required for microbiological experiments are described. This apparatus is able to handle a large number of samples and has the unique shaking mechanism which is to strike the lower part of the test tubes with reciprocally moving bars. Besides fundamental operations, such as injection of samples and medium, inoculation and repeated measurements of bacterial growth, the apparatus allows the addition of samples and removal of culture broth at the desired time during the incubation period without the researcher's attendance. These functions are combined to make the apparatus very versatile for microbiological experiments, saving on night-time and holiday working and increasing efficiency in experiments. Some practical applications of this apparatus for microbioassay and fermentation experiments are described. The automated method is shown to be advantageous in assay precision and in obtaining detailed information.     

Growth of Nitrosomonas europaea in batch and in continuous culture

Summary Techniques are described in this paper for growing Nitrosomonas europea in batch and in continuous culture with apparatus constructed from readily available laboratory materials.The methods employed in batch culture have enabled the collection of cells concentrated in small volumes. Nitrosomonas europaea has been grown successfully in continuous culture and yields of 23 g wet weight were obtained, an average of 0.16 g/l with a flow rate of 300 ml/h over twenty days. Results show that high levels of nitrite do not materially affect the growth of the bacterium. The continuous culture equipment has also been used to grow Azotobacter vinelandii and Thiobacillus concretivorus.     

A Method for Harvesting Mass Cultures of Tetrahymena pyriformis

SYNOPSIS. A centrifugation procedure for removing Tetrahymena from mass cultures is described. This method offers the following advantages: (a) inexpensive apparatus, (b) the short period of time required for harvesting large numbers of cells, (c) lack of cellular damage, (d) the ability to obtain proven dilution with regard to the culture fluid, (e) nearly quantitative recovery of the cells, and (f) the ease of assembling and disassembling the apparatus for cleaning.     

New suspension culture system (Mini-AR).

A new suspension culture system (Mini-AR) based on the Stoke's drag law for suspended particles is described. This apparatus can be utilized for the maintenance of mammalian kidney cells in both short- and long-term cultures.     

A method for the regulation of microbial population density during continuous culture at high growth rates

A method for the continuous culture of microorganisms is described which employs growth-dependent pH changes to control the rate of addition of fresh medium to a culture vessel. The apparatus (the phauxostat) supports, at constant pH, longterm continuous culture at rates near or at the maximum of which the organisms are capable. The buffering capacity of the inflowing medium determines the steady-state population density of the culture, but the rate of growth is independent of the buffering capacity. The fundamental theory of operation is tested and some basic parameters of growth are estimated using Escherichia coli B growing continuously in media containing glucose, glycerol or DL-lactate.Joseph C. Wilson Scholar.     

Apparatus for Metabolic Studies with Anaerobes

An apparatus is described which allows metabolic experiments with obligate anaerobic bacteria to be performed with minimal disturbance of the E(h) of the culture.     

Multichannel plating unit for high-throughput plating of cell cultures

High-throughput genomic approaches to gene function or target identification have led to the development and implementation of the 96-well format for many standard molecular biology manipulations. The apparatus described here, a Multichannel Plating Unit, is designed to plate out individual cultures efficientlyfrom standard 96-well culture blocks. Following transformation, aliquots of culture are loaded onto sterile beads that are rolled along individual channels of agar media. After the beads traverse the channel, they drop into the exit alley for disposal via an exit pore. The apparatus presented has 12 individual lanes, and the spacing is compatible with a standard 12-channel pipettor Thus, the unit allows for the rapid plating of 12 individual cultures at a time. For one 96-well block of transformants, this method reduces the labeling and plating effort from 96 culture dishes that are spread individually to eight multichannel plates. The savings in time, materials, and storage space is significant     

A method for the control of the dissolved oxygen tension in microbial cultures

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.     

The cyclone column culture vessel for batch and continuous,synchronous or asynchronous,culture of microorganisms

A simple inexpensive apparatus with a working volume of 10 liters of culture is described. Details of construction and procedures for operation of the cyclone column vessel are given. The vessel is self-contained, so that experimental parameters of temperature and aeration are individually controlled; homogeneous mixing and representative sampling of the culture, besides control of foam without need for antifoam, are obtained. The vessel may be used in single or multistage systems for aerobic or anaerobic cultivation of organisms in batch, chemostat, or phased cultures.     

Enhanced Yields of Iron-Oxidizing Bacteria by In Situ Electrochemical Reduction of Soluble Iron in the Growth Medium

An electrochemical apparatus for culturing chemolithotrophic bacteria that respire aerobically on ferrous ions is described. Enhanced yields of the bacteria were achieved by the in situ electrochemical reduction of soluble iron in the growth medium. When subjected to a direct current of 30 A for 60 days, a 45-liter culture of Thiobacillus ferrooxidans grew from 6 × 10⁷ to 9.5 × 10⁹ cells per ml. Growth of the bacterium within the electrolytic bioreactor was linear with time. A final cell density corresponding to 4.7 g of wet cell paste per liter was achieved, and a total of 320 g of wet cell paste was harvested from one culture. The apparatus was designed to deliver protons concomitantly with electrons; therefore, the pH of the culture remained stable at 1.6 ± 0.1 for the duration of growth. This laboratory-scale apparatus may be readily adapted to pilot or production scale. It is thus anticipated that abundant numbers of iron-oxidizing bacteria may be obtained for both fundamental and applied studies.     

An apparatus for continuous analysis of protease-catalyzed acyl transfer reactions

An apparatus that allows continuous analysis of protease-catalyzed acyl transfer reactions is described. Hydrolysis reaction is assayed using automatic titration. A continuous determination of amino group concentration by reaction with o-phthalaldehyde gives the rate of peptide bond formation. The apparatus allows the determination of the partition constant for the nucleophile at various nucleophile concentrations from one run.     

Attached Growth of Sphaerotilus and Mixed Populations in a Continuous-flow Apparatus

The effects of NH(4)Cl concentration, organic nitrogen compounds, glucose concentration, dissolved oxygen concentration, and flow rate on the attached growth of pure cultures of Sphaerotilus natans and of a mixed population in a continuous-flow apparatus are described. Low concentrations of NH(4)Cl and oxygen, and high flow rates resulted in attached populations that were dominated by Sphaerotilus. The conditions that allowed maximal attached growth in pure culture did not correspond to the conditions that promoted attached growth of Sphaerotilus in a mixed population.     

Automatic Assessment of Respiration During Growth in Stirred Fermentors

An apparatus for the continuous and automatic measurement of respiration during growth of micro-organisms in stirred aerated culture is described. The effluent atmosphere from the culture vessels is passed through commercially available oxygen and carbon dioxide gas analyzers, and their electrical output is fed to a multipoint recorder. The apparatus has been used to measure the respiration of Escherichia coli, Pseudomonas aeruginosa, Bacillus thuringiensis, and Methylococcus capsulatus during growth on complex and defined media. In addition, pH values and dissolved oxygen concentrations were measured. Growth of P. thuringiensis in glucose-limited media showed unexpected interruptions in the oxygen consumption curves which resembled diauxic growth; growth of B. thuringiensis in complex media showed similar discontinuities of respiration. These results are explained as the sequential utilization of preferred substrates which, in the case of P. aeruginosa were provided as transient intermediates of glucose.